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Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Browse Source 
Pull locking updates from Ingo Molnar:
 "The main changes in this cycle were:

   - a big round of FUTEX_UNLOCK_PI improvements, fixes, cleanups and
     general restructuring

   - lockdep updates such as new checks for lock_downgrade()

   - introduce the new atomic_try_cmpxchg() locking API and use it to
     optimize refcount code generation

   - ... plus misc fixes, updates and cleanups"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits)
  MAINTAINERS: Add FUTEX SUBSYSTEM
  futex: Clarify mark_wake_futex memory barrier usage
  futex: Fix small (and harmless looking) inconsistencies
  futex: Avoid freeing an active timer
  rtmutex: Plug preempt count leak in rt_mutex_futex_unlock()
  rtmutex: Fix more prio comparisons
  rtmutex: Fix PI chain order integrity
  sched,tracing: Update trace_sched_pi_setprio()
  sched/rtmutex: Refactor rt_mutex_setprio()
  rtmutex: Clean up
  sched/deadline/rtmutex: Dont miss the dl_runtime/dl_period update
  sched/rtmutex/deadline: Fix a PI crash for deadline tasks
  rtmutex: Deboost before waking up the top waiter
  locking/ww-mutex: Limit stress test to 2 seconds
  locking/atomic: Fix atomic_try_cmpxchg() semantics
  lockdep: Fix per-cpu static objects
  futex: Drop hb->lock before enqueueing on the rtmutex
  futex: Futex_unlock_pi() determinism
  futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()
  futex,rt_mutex: Restructure rt_mutex_finish_proxy_lock()
  ...
This commit is contained in:
Linus Torvalds 2017-05-01 19:36:00 -07:00
commit 207fb8c304
29 changed files with 1234 additions and 613 deletions
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17
MAINTAINERS
View File

@ -5415,6 +5415,23 @@ F: fs/fuse/
F: include/uapi/linux/fuse.h
F: Documentation/filesystems/fuse.txt
FUTEX SUBSYSTEM
M: Thomas Gleixner <tglx@linutronix.de>
M: Ingo Molnar <mingo@redhat.com>
R: Peter Zijlstra <peterz@infradead.org>
R: Darren Hart <dvhart@infradead.org>
L: linux-kernel@vger.kernel.org
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git locking/core
S: Maintained
F: kernel/futex.c
F: kernel/futex_compat.c
F: include/asm-generic/futex.h
F: include/linux/futex.h
F: include/uapi/linux/futex.h
F: tools/testing/selftests/futex/
F: tools/perf/bench/futex*
F: Documentation/*futex*
FUTURE DOMAIN TMC-16x0 SCSI DRIVER (16-bit)
M: Rik Faith <faith@cs.unc.edu>
L: linux-scsi@vger.kernel.org

33
arch/x86/include/asm/atomic.h
View File

@ -186,6 +186,12 @@ static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
return cmpxchg(&v->counter, old, new);
}
#define atomic_try_cmpxchg atomic_try_cmpxchg
static __always_inline bool atomic_try_cmpxchg(atomic_t *v, int *old, int new)
{
return try_cmpxchg(&v->counter, old, new);
}
static inline int atomic_xchg(atomic_t *v, int new)
{
return xchg(&v->counter, new);
@ -201,16 +207,12 @@ static inline void atomic_##op(int i, atomic_t *v) \
}
#define ATOMIC_FETCH_OP(op, c_op) \
static inline int atomic_fetch_##op(int i, atomic_t *v) \
static inline int atomic_fetch_##op(int i, atomic_t *v) \
{ \
int old, val = atomic_read(v); \
for (;;) { \
old = atomic_cmpxchg(v, val, val c_op i); \
if (old == val) \
break; \
val = old; \
} \
return old; \
int val = atomic_read(v); \
do { \
} while (!atomic_try_cmpxchg(v, &val, val c_op i)); \
return val; \
}
#define ATOMIC_OPS(op, c_op) \
@ -236,16 +238,11 @@ ATOMIC_OPS(xor, ^)
*/
static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
int c, old;
c = atomic_read(v);
for (;;) {
if (unlikely(c == (u)))
int c = atomic_read(v);
do {
if (unlikely(c == u))
break;
old = atomic_cmpxchg((v), c, c + (a));
if (likely(old == c))
break;
c = old;
}
} while (!atomic_try_cmpxchg(v, &c, c + a));
return c;
}

46
arch/x86/include/asm/atomic64_64.h
View File

@ -176,6 +176,12 @@ static inline long atomic64_cmpxchg(atomic64_t *v, long old, long new)
return cmpxchg(&v->counter, old, new);
}
#define atomic64_try_cmpxchg atomic64_try_cmpxchg
static __always_inline bool atomic64_try_cmpxchg(atomic64_t *v, long *old, long new)
{
return try_cmpxchg(&v->counter, old, new);
}
static inline long atomic64_xchg(atomic64_t *v, long new)
{
return xchg(&v->counter, new);
@ -192,17 +198,12 @@ static inline long atomic64_xchg(atomic64_t *v, long new)
*/
static inline bool atomic64_add_unless(atomic64_t *v, long a, long u)
{
long c, old;
c = atomic64_read(v);
for (;;) {
if (unlikely(c == (u)))
break;
old = atomic64_cmpxchg((v), c, c + (a));
if (likely(old == c))
break;
c = old;
}
return c != (u);
long c = atomic64_read(v);
do {
if (unlikely(c == u))
return false;
} while (!atomic64_try_cmpxchg(v, &c, c + a));
return true;
}
#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
@ -216,17 +217,12 @@ static inline bool atomic64_add_unless(atomic64_t *v, long a, long u)
*/
static inline long atomic64_dec_if_positive(atomic64_t *v)
{
long c, old, dec;
c = atomic64_read(v);
for (;;) {
long dec, c = atomic64_read(v);
do {
dec = c - 1;
if (unlikely(dec < 0))
break;
old = atomic64_cmpxchg((v), c, dec);
if (likely(old == c))
break;
c = old;
}
} while (!atomic64_try_cmpxchg(v, &c, dec));
return dec;
}
@ -242,14 +238,10 @@ static inline void atomic64_##op(long i, atomic64_t *v) \
#define ATOMIC64_FETCH_OP(op, c_op) \
static inline long atomic64_fetch_##op(long i, atomic64_t *v) \
{ \
long old, val = atomic64_read(v); \
for (;;) { \
old = atomic64_cmpxchg(v, val, val c_op i); \
if (old == val) \
break; \
val = old; \
} \
return old; \
long val = atomic64_read(v); \
do { \
} while (!atomic64_try_cmpxchg(v, &val, val c_op i)); \
return val; \
}
#define ATOMIC64_OPS(op, c_op) \

70
arch/x86/include/asm/cmpxchg.h
View File

@ -153,6 +153,76 @@ extern void __add_wrong_size(void)
#define cmpxchg_local(ptr, old, new) \
__cmpxchg_local(ptr, old, new, sizeof(*(ptr)))
#define __raw_try_cmpxchg(_ptr, _pold, _new, size, lock) \
({ \
bool success; \
__typeof__(_ptr) _old = (_pold); \
__typeof__(*(_ptr)) __old = *_old; \
__typeof__(*(_ptr)) __new = (_new); \
switch (size) { \
case __X86_CASE_B: \
{ \
volatile u8 *__ptr = (volatile u8 *)(_ptr); \
asm volatile(lock "cmpxchgb %[new], %[ptr]" \
CC_SET(z) \
: CC_OUT(z) (success), \
[ptr] "+m" (*__ptr), \
[old] "+a" (__old) \
: [new] "q" (__new) \
: "memory"); \
break; \
} \
case __X86_CASE_W: \
{ \
volatile u16 *__ptr = (volatile u16 *)(_ptr); \
asm volatile(lock "cmpxchgw %[new], %[ptr]" \
CC_SET(z) \
: CC_OUT(z) (success), \
[ptr] "+m" (*__ptr), \
[old] "+a" (__old) \
: [new] "r" (__new) \
: "memory"); \
break; \
} \
case __X86_CASE_L: \
{ \
volatile u32 *__ptr = (volatile u32 *)(_ptr); \
asm volatile(lock "cmpxchgl %[new], %[ptr]" \
CC_SET(z) \
: CC_OUT(z) (success), \
[ptr] "+m" (*__ptr), \
[old] "+a" (__old) \
: [new] "r" (__new) \
: "memory"); \
break; \
} \
case __X86_CASE_Q: \
{ \
volatile u64 *__ptr = (volatile u64 *)(_ptr); \
asm volatile(lock "cmpxchgq %[new], %[ptr]" \
CC_SET(z) \
: CC_OUT(z) (success), \
[ptr] "+m" (*__ptr), \
[old] "+a" (__old) \
: [new] "r" (__new) \
: "memory"); \
break; \
} \
default: \
__cmpxchg_wrong_size(); \
} \
if (unlikely(!success)) \
*_old = __old; \
likely(success); \
})
#define __try_cmpxchg(ptr, pold, new, size) \
__raw_try_cmpxchg((ptr), (pold), (new), (size), LOCK_PREFIX)
#define try_cmpxchg(ptr, pold, new) \
__try_cmpxchg((ptr), (pold), (new), sizeof(*(ptr)))
/*
* xadd() adds "inc" to "*ptr" and atomically returns the previous
* value of "*ptr".

46
include/linux/atomic.h
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@ -423,6 +423,29 @@
#endif
#endif /* atomic_cmpxchg_relaxed */
#ifndef atomic_try_cmpxchg
#define __atomic_try_cmpxchg(type, _p, _po, _n) \
({ \
typeof(_po) __po = (_po); \
typeof(*(_po)) __r, __o = *__po; \
__r = atomic_cmpxchg##type((_p), __o, (_n)); \
if (unlikely(__r != __o)) \
*__po = __r; \
likely(__r == __o); \
})
#define atomic_try_cmpxchg(_p, _po, _n) __atomic_try_cmpxchg(, _p, _po, _n)
#define atomic_try_cmpxchg_relaxed(_p, _po, _n) __atomic_try_cmpxchg(_relaxed, _p, _po, _n)
#define atomic_try_cmpxchg_acquire(_p, _po, _n) __atomic_try_cmpxchg(_acquire, _p, _po, _n)
#define atomic_try_cmpxchg_release(_p, _po, _n) __atomic_try_cmpxchg(_release, _p, _po, _n)
#else /* atomic_try_cmpxchg */
#define atomic_try_cmpxchg_relaxed atomic_try_cmpxchg
#define atomic_try_cmpxchg_acquire atomic_try_cmpxchg
#define atomic_try_cmpxchg_release atomic_try_cmpxchg
#endif /* atomic_try_cmpxchg */
/* cmpxchg_relaxed */
#ifndef cmpxchg_relaxed
#define cmpxchg_relaxed cmpxchg
@ -996,6 +1019,29 @@ static inline int atomic_dec_if_positive(atomic_t *v)
#endif
#endif /* atomic64_cmpxchg_relaxed */
#ifndef atomic64_try_cmpxchg
#define __atomic64_try_cmpxchg(type, _p, _po, _n) \
({ \
typeof(_po) __po = (_po); \
typeof(*(_po)) __r, __o = *__po; \
__r = atomic64_cmpxchg##type((_p), __o, (_n)); \
if (unlikely(__r != __o)) \
*__po = __r; \
likely(__r == __o); \
})
#define atomic64_try_cmpxchg(_p, _po, _n) __atomic64_try_cmpxchg(, _p, _po, _n)
#define atomic64_try_cmpxchg_relaxed(_p, _po, _n) __atomic64_try_cmpxchg(_relaxed, _p, _po, _n)
#define atomic64_try_cmpxchg_acquire(_p, _po, _n) __atomic64_try_cmpxchg(_acquire, _p, _po, _n)
#define atomic64_try_cmpxchg_release(_p, _po, _n) __atomic64_try_cmpxchg(_release, _p, _po, _n)
#else /* atomic64_try_cmpxchg */
#define atomic64_try_cmpxchg_relaxed atomic64_try_cmpxchg
#define atomic64_try_cmpxchg_acquire atomic64_try_cmpxchg
#define atomic64_try_cmpxchg_release atomic64_try_cmpxchg
#endif /* atomic64_try_cmpxchg */
#ifndef atomic64_andnot
static inline void atomic64_andnot(long long i, atomic64_t *v)
{

1
include/linux/init_task.h
View File

@ -181,6 +181,7 @@ extern struct cred init_cred;
#ifdef CONFIG_RT_MUTEXES
# define INIT_RT_MUTEXES(tsk) \
.pi_waiters = RB_ROOT, \
.pi_top_task = NULL, \
.pi_waiters_leftmost = NULL,
#else
# define INIT_RT_MUTEXES(tsk)

3
include/linux/lockdep.h
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@ -361,6 +361,8 @@ static inline void lock_set_subclass(struct lockdep_map *lock,
lock_set_class(lock, lock->name, lock->key, subclass, ip);
}
extern void lock_downgrade(struct lockdep_map *lock, unsigned long ip);
extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
extern void lockdep_clear_current_reclaim_state(void);
extern void lockdep_trace_alloc(gfp_t mask);
@ -411,6 +413,7 @@ static inline void lockdep_on(void)
# define lock_acquire(l, s, t, r, c, n, i) do { } while (0)
# define lock_release(l, n, i) do { } while (0)
# define lock_downgrade(l, i) do { } while (0)
# define lock_set_class(l, n, k, s, i) do { } while (0)
# define lock_set_subclass(l, s, i) do { } while (0)
# define lockdep_set_current_reclaim_state(g) do { } while (0)

6
include/linux/module.h
View File

@ -493,6 +493,7 @@ static inline int module_is_live(struct module *mod)
struct module *__module_text_address(unsigned long addr);
struct module *__module_address(unsigned long addr);
bool is_module_address(unsigned long addr);
bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr);
bool is_module_percpu_address(unsigned long addr);
bool is_module_text_address(unsigned long addr);
@ -660,6 +661,11 @@ static inline bool is_module_percpu_address(unsigned long addr)
return false;
}
static inline bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
{
return false;
}
static inline bool is_module_text_address(unsigned long addr)
{
return false;

1
include/linux/percpu.h
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@ -110,6 +110,7 @@ extern int __init pcpu_page_first_chunk(size_t reserved_size,
#endif
extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align);
extern bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr);
extern bool is_kernel_percpu_address(unsigned long addr);
#if !defined(CONFIG_SMP) || !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)

19
include/linux/refcount.h
View File

@ -6,17 +6,36 @@
#include <linux/spinlock.h>
#include <linux/kernel.h>
/**
* refcount_t - variant of atomic_t specialized for reference counts
* @refs: atomic_t counter field
*
* The counter saturates at UINT_MAX and will not move once
* there. This avoids wrapping the counter and causing 'spurious'
* use-after-free bugs.
*/
typedef struct refcount_struct {
atomic_t refs;
} refcount_t;
#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), }
/**
* refcount_set - set a refcount's value
* @r: the refcount
* @n: value to which the refcount will be set
*/
static inline void refcount_set(refcount_t *r, unsigned int n)
{
atomic_set(&r->refs, n);
}
/**
* refcount_read - get a refcount's value
* @r: the refcount
*
* Return: the refcount's value
*/
static inline unsigned int refcount_read(const refcount_t *r)
{
return atomic_read(&r->refs);

2
include/linux/sched.h
View File

@ -779,6 +779,8 @@ struct task_struct {
/* PI waiters blocked on a rt_mutex held by this task: */
struct rb_root pi_waiters;
struct rb_node *pi_waiters_leftmost;
/* Updated under owner's pi_lock and rq lock */
struct task_struct *pi_top_task;
/* Deadlock detection and priority inheritance handling: */
struct rt_mutex_waiter *pi_blocked_on;
#endif

23
include/linux/sched/rt.h
View File

@ -18,27 +18,20 @@ static inline int rt_task(struct task_struct *p)
}
#ifdef CONFIG_RT_MUTEXES
extern int rt_mutex_getprio(struct task_struct *p);
extern void rt_mutex_setprio(struct task_struct *p, int prio);
extern int rt_mutex_get_effective_prio(struct task_struct *task, int newprio);
extern struct task_struct *rt_mutex_get_top_task(struct task_struct *task);
/*
* Must hold either p->pi_lock or task_rq(p)->lock.
*/
static inline struct task_struct *rt_mutex_get_top_task(struct task_struct *p)
{
return p->pi_top_task;
}
extern void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task);
extern void rt_mutex_adjust_pi(struct task_struct *p);
static inline bool tsk_is_pi_blocked(struct task_struct *tsk)
{
return tsk->pi_blocked_on != NULL;
}
#else
static inline int rt_mutex_getprio(struct task_struct *p)
{
return p->normal_prio;
}
static inline int rt_mutex_get_effective_prio(struct task_struct *task,
int newprio)
{
return newprio;
}
static inline struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
{
return NULL;

12
include/linux/smp.h
View File

@ -120,6 +120,13 @@ extern unsigned int setup_max_cpus;
extern void __init setup_nr_cpu_ids(void);
extern void __init smp_init(void);
extern int __boot_cpu_id;
static inline int get_boot_cpu_id(void)
{
return __boot_cpu_id;
}
#else /* !SMP */
static inline void smp_send_stop(void) { }
@ -158,6 +165,11 @@ static inline void smp_init(void) { up_late_init(); }
static inline void smp_init(void) { }
#endif
static inline int get_boot_cpu_id(void)
{
return 0;
}
#endif /* !SMP */
/*

16
include/trace/events/sched.h
View File

@ -70,7 +70,7 @@ DECLARE_EVENT_CLASS(sched_wakeup_template,
TP_fast_assign(
memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
__entry->pid = p->pid;
__entry->prio = p->prio;
__entry->prio = p->prio; /* XXX SCHED_DEADLINE */
__entry->success = 1; /* rudiment, kill when possible */
__entry->target_cpu = task_cpu(p);
),
@ -147,6 +147,7 @@ TRACE_EVENT(sched_switch,
memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
__entry->next_pid = next->pid;
__entry->next_prio = next->prio;
/* XXX SCHED_DEADLINE */
),
TP_printk("prev_comm=%s prev_pid=%d prev_prio=%d prev_state=%s%s ==> next_comm=%s next_pid=%d next_prio=%d",
@ -181,7 +182,7 @@ TRACE_EVENT(sched_migrate_task,
TP_fast_assign(
memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
__entry->pid = p->pid;
__entry->prio = p->prio;
__entry->prio = p->prio; /* XXX SCHED_DEADLINE */
__entry->orig_cpu = task_cpu(p);
__entry->dest_cpu = dest_cpu;
),
@ -206,7 +207,7 @@ DECLARE_EVENT_CLASS(sched_process_template,
TP_fast_assign(
memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
__entry->pid = p->pid;
__entry->prio = p->prio;
__entry->prio = p->prio; /* XXX SCHED_DEADLINE */
),
TP_printk("comm=%s pid=%d prio=%d",
@ -253,7 +254,7 @@ TRACE_EVENT(sched_process_wait,
TP_fast_assign(
memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
__entry->pid = pid_nr(pid);
__entry->prio = current->prio;
__entry->prio = current->prio; /* XXX SCHED_DEADLINE */
),
TP_printk("comm=%s pid=%d prio=%d",
@ -413,9 +414,9 @@ DEFINE_EVENT(sched_stat_runtime, sched_stat_runtime,
*/
TRACE_EVENT(sched_pi_setprio,
TP_PROTO(struct task_struct *tsk, int newprio),
TP_PROTO(struct task_struct *tsk, struct task_struct *pi_task),
TP_ARGS(tsk, newprio),
TP_ARGS(tsk, pi_task),
TP_STRUCT__entry(
__array( char, comm, TASK_COMM_LEN )
@ -428,7 +429,8 @@ TRACE_EVENT(sched_pi_setprio,
memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN);
__entry->pid = tsk->pid;
__entry->oldprio = tsk->prio;
__entry->newprio = newprio;
__entry->newprio = pi_task ? pi_task->prio : tsk->prio;
/* XXX SCHED_DEADLINE bits missing */
),
TP_printk("comm=%s pid=%d oldprio=%d newprio=%d",

6
kernel/cpu.c
View File

@ -1125,6 +1125,8 @@ core_initcall(cpu_hotplug_pm_sync_init);
#endif /* CONFIG_PM_SLEEP_SMP */
int __boot_cpu_id;
#endif /* CONFIG_SMP */
/* Boot processor state steps */
@ -1815,6 +1817,10 @@ void __init boot_cpu_init(void)
set_cpu_active(cpu, true);
set_cpu_present(cpu, true);
set_cpu_possible(cpu, true);
#ifdef CONFIG_SMP
__boot_cpu_id = cpu;
#endif
}
/*

1
kernel/fork.c
View File

@ -1438,6 +1438,7 @@ static void rt_mutex_init_task(struct task_struct *p)
#ifdef CONFIG_RT_MUTEXES
p->pi_waiters = RB_ROOT;
p->pi_waiters_leftmost = NULL;
p->pi_top_task = NULL;
p->pi_blocked_on = NULL;
#endif
}

518
kernel/futex.c
View File

@ -802,7 +802,7 @@ static int refill_pi_state_cache(void)
return 0;
}
static struct futex_pi_state * alloc_pi_state(void)
static struct futex_pi_state *alloc_pi_state(void)
{
struct futex_pi_state *pi_state = current->pi_state_cache;
@ -812,6 +812,11 @@ static struct futex_pi_state * alloc_pi_state(void)
return pi_state;
}
static void get_pi_state(struct futex_pi_state *pi_state)
{
WARN_ON_ONCE(!atomic_inc_not_zero(&pi_state->refcount));
}
/*
* Drops a reference to the pi_state object and frees or caches it
* when the last reference is gone.
@ -856,7 +861,7 @@ static void put_pi_state(struct futex_pi_state *pi_state)
* Look up the task based on what TID userspace gave us.
* We dont trust it.
*/
static struct task_struct * futex_find_get_task(pid_t pid)
static struct task_struct *futex_find_get_task(pid_t pid)
{
struct task_struct *p;
@ -916,10 +921,12 @@ void exit_pi_state_list(struct task_struct *curr)
pi_state->owner = NULL;
raw_spin_unlock_irq(&curr->pi_lock);
rt_mutex_unlock(&pi_state->pi_mutex);
get_pi_state(pi_state);
spin_unlock(&hb->lock);
rt_mutex_futex_unlock(&pi_state->pi_mutex);
put_pi_state(pi_state);
raw_spin_lock_irq(&curr->pi_lock);
}
raw_spin_unlock_irq(&curr->pi_lock);
@ -973,6 +980,39 @@ void exit_pi_state_list(struct task_struct *curr)
*
* [10] There is no transient state which leaves owner and user space
* TID out of sync.
*
*
* Serialization and lifetime rules:
*
* hb->lock:
*
* hb -> futex_q, relation
* futex_q -> pi_state, relation
*
* (cannot be raw because hb can contain arbitrary amount
* of futex_q's)
*
* pi_mutex->wait_lock:
*
* {uval, pi_state}
*
* (and pi_mutex 'obviously')
*
* p->pi_lock:
*
* p->pi_state_list -> pi_state->list, relation
*
* pi_state->refcount:
*
* pi_state lifetime
*
*
* Lock order:
*
* hb->lock
* pi_mutex->wait_lock
* p->pi_lock
*
*/
/*
@ -980,10 +1020,13 @@ void exit_pi_state_list(struct task_struct *curr)
* the pi_state against the user space value. If correct, attach to
* it.
*/
static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state,
static int attach_to_pi_state(u32 __user *uaddr, u32 uval,
struct futex_pi_state *pi_state,
struct futex_pi_state **ps)
{
pid_t pid = uval & FUTEX_TID_MASK;
u32 uval2;
int ret;
/*
* Userspace might have messed up non-PI and PI futexes [3]
@ -991,8 +1034,38 @@ static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state,
if (unlikely(!pi_state))
return -EINVAL;
/*
* We get here with hb->lock held, and having found a
* futex_top_waiter(). This means that futex_lock_pi() of said futex_q
* has dropped the hb->lock in between queue_me() and unqueue_me_pi(),
* which in turn means that futex_lock_pi() still has a reference on
* our pi_state.
*
* The waiter holding a reference on @pi_state also protects against
* the unlocked put_pi_state() in futex_unlock_pi(), futex_lock_pi()
* and futex_wait_requeue_pi() as it cannot go to 0 and consequently
* free pi_state before we can take a reference ourselves.
*/
WARN_ON(!atomic_read(&pi_state->refcount));
/*
* Now that we have a pi_state, we can acquire wait_lock
* and do the state validation.
*/
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
/*
* Since {uval, pi_state} is serialized by wait_lock, and our current
* uval was read without holding it, it can have changed. Verify it
* still is what we expect it to be, otherwise retry the entire
* operation.
*/
if (get_futex_value_locked(&uval2, uaddr))
goto out_efault;
if (uval != uval2)
goto out_eagain;
/*
* Handle the owner died case:
*/
@ -1008,11 +1081,11 @@ static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state,
* is not 0. Inconsistent state. [5]
*/
if (pid)
return -EINVAL;
goto out_einval;
/*
* Take a ref on the state and return success. [4]
*/
goto out_state;
goto out_attach;
}
/*
@ -1024,14 +1097,14 @@ static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state,
* Take a ref on the state and return success. [6]
*/
if (!pid)
goto out_state;
goto out_attach;
} else {
/*
* If the owner died bit is not set, then the pi_state
* must have an owner. [7]
*/
if (!pi_state->owner)
return -EINVAL;
goto out_einval;
}
/*
@ -1040,11 +1113,29 @@ static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state,
* user space TID. [9/10]
*/
if (pid != task_pid_vnr(pi_state->owner))
return -EINVAL;
out_state:
atomic_inc(&pi_state->refcount);
goto out_einval;
out_attach:
get_pi_state(pi_state);
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
*ps = pi_state;
return 0;
out_einval:
ret = -EINVAL;
goto out_error;
out_eagain:
ret = -EAGAIN;
goto out_error;
out_efault:
ret = -EFAULT;
goto out_error;
out_error:
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
return ret;
}
/*
@ -1095,6 +1186,9 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key,
/*
* No existing pi state. First waiter. [2]
*
* This creates pi_state, we have hb->lock held, this means nothing can
* observe this state, wait_lock is irrelevant.
*/
pi_state = alloc_pi_state();
@ -1119,17 +1213,18 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key,
return 0;
}
static int lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
static int lookup_pi_state(u32 __user *uaddr, u32 uval,
struct futex_hash_bucket *hb,
union futex_key *key, struct futex_pi_state **ps)
{
struct futex_q *match = futex_top_waiter(hb, key);
struct futex_q *top_waiter = futex_top_waiter(hb, key);
/*
* If there is a waiter on that futex, validate it and
* attach to the pi_state when the validation succeeds.
*/
if (match)
return attach_to_pi_state(uval, match->pi_state, ps);
if (top_waiter)
return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps);
/*
* We are the first waiter - try to look up the owner based on
@ -1148,7 +1243,7 @@ static int lock_pi_update_atomic(u32 __user *uaddr, u32 uval, u32 newval)
if (unlikely(cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)))
return -EFAULT;
/*If user space value changed, let the caller retry */
/* If user space value changed, let the caller retry */
return curval != uval ? -EAGAIN : 0;
}
@ -1176,7 +1271,7 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb,
struct task_struct *task, int set_waiters)
{
u32 uval, newval, vpid = task_pid_vnr(task);
struct futex_q *match;
struct futex_q *top_waiter;
int ret;
/*
@ -1202,9 +1297,9 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb,
* Lookup existing state first. If it exists, try to attach to
* its pi_state.
*/
match = futex_top_waiter(hb, key);
if (match)
return attach_to_pi_state(uval, match->pi_state, ps);
top_waiter = futex_top_waiter(hb, key);
if (top_waiter)
return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps);
/*
* No waiter and user TID is 0. We are here because the
@ -1285,50 +1380,44 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q)
wake_q_add(wake_q, p);
__unqueue_futex(q);
/*
* The waiting task can free the futex_q as soon as
* q->lock_ptr = NULL is written, without taking any locks. A
* memory barrier is required here to prevent the following
* store to lock_ptr from getting ahead of the plist_del.
* The waiting task can free the futex_q as soon as q->lock_ptr = NULL
* is written, without taking any locks. This is possible in the event
* of a spurious wakeup, for example. A memory barrier is required here
* to prevent the following store to lock_ptr from getting ahead of the
* plist_del in __unqueue_futex().
*/
smp_wmb();
q->lock_ptr = NULL;
smp_store_release(&q->lock_ptr, NULL);
}
static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
struct futex_hash_bucket *hb)
/*
* Caller must hold a reference on @pi_state.
*/
static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_state)
{
struct task_struct *new_owner;
struct futex_pi_state *pi_state = this->pi_state;
u32 uninitialized_var(curval), newval;
struct task_struct *new_owner;
bool postunlock = false;
DEFINE_WAKE_Q(wake_q);
bool deboost;
int ret = 0;
if (!pi_state)
return -EINVAL;
/*
* If current does not own the pi_state then the futex is
* inconsistent and user space fiddled with the futex value.
*/
if (pi_state->owner != current)
return -EINVAL;
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
if (WARN_ON_ONCE(!new_owner)) {
/*
* As per the comment in futex_unlock_pi() this should not happen.
*
* When this happens, give up our locks and try again, giving
* the futex_lock_pi() instance time to complete, either by
* waiting on the rtmutex or removing itself from the futex
* queue.
*/
ret = -EAGAIN;
goto out_unlock;
}
/*
* It is possible that the next waiter (the one that brought
* this owner to the kernel) timed out and is no longer
* waiting on the lock.
*/
if (!new_owner)
new_owner = this->task;
/*
* We pass it to the next owner. The WAITERS bit is always
* kept enabled while there is PI state around. We cleanup the
* owner died bit, because we are the owner.
* We pass it to the next owner. The WAITERS bit is always kept
* enabled while there is PI state around. We cleanup the owner
* died bit, because we are the owner.
*/
newval = FUTEX_WAITERS | task_pid_vnr(new_owner);
@ -1337,6 +1426,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)) {
ret = -EFAULT;
} else if (curval != uval) {
/*
* If a unconditional UNLOCK_PI operation (user space did not
@ -1349,10 +1439,14 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
else
ret = -EINVAL;
}
if (ret) {
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
return ret;
}
if (ret)
goto out_unlock;
/*
* This is a point of no return; once we modify the uval there is no
* going back and subsequent operations must not fail.
*/
raw_spin_lock(&pi_state->owner->pi_lock);
WARN_ON(list_empty(&pi_state->list));
@ -1365,22 +1459,15 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
pi_state->owner = new_owner;
raw_spin_unlock(&new_owner->pi_lock);
postunlock = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);
out_unlock:
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
deboost = rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);
if (postunlock)
rt_mutex_postunlock(&wake_q);
/*
* First unlock HB so the waiter does not spin on it once he got woken
* up. Second wake up the waiter before the priority is adjusted. If we
* deboost first (and lose our higher priority), then the task might get
* scheduled away before the wake up can take place.
*/
spin_unlock(&hb->lock);
wake_up_q(&wake_q);
if (deboost)
rt_mutex_adjust_prio(current);
return 0;
return ret;
}
/*
@ -1826,7 +1913,7 @@ retry_private:
* If that call succeeds then we have pi_state and an
* initial refcount on it.
*/
ret = lookup_pi_state(ret, hb2, &key2, &pi_state);
ret = lookup_pi_state(uaddr2, ret, hb2, &key2, &pi_state);
}
switch (ret) {
@ -1909,7 +1996,7 @@ retry_private:
* refcount on the pi_state and store the pointer in
* the futex_q object of the waiter.
*/
atomic_inc(&pi_state->refcount);
get_pi_state(pi_state);
this->pi_state = pi_state;
ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex,
this->rt_waiter,
@ -2009,20 +2096,7 @@ queue_unlock(struct futex_hash_bucket *hb)
hb_waiters_dec(hb);
}
/**
* queue_me() - Enqueue the futex_q on the futex_hash_bucket
* @q: The futex_q to enqueue
* @hb: The destination hash bucket
*
* The hb->lock must be held by the caller, and is released here. A call to
* queue_me() is typically paired with exactly one call to unqueue_me(). The
* exceptions involve the PI related operations, which may use unqueue_me_pi()
* or nothing if the unqueue is done as part of the wake process and the unqueue
* state is implicit in the state of woken task (see futex_wait_requeue_pi() for
* an example).
*/
static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
__releases(&hb->lock)
static inline void __queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
{
int prio;
@ -2039,6 +2113,24 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
plist_node_init(&q->list, prio);
plist_add(&q->list, &hb->chain);
q->task = current;
}
/**
* queue_me() - Enqueue the futex_q on the futex_hash_bucket
* @q: The futex_q to enqueue
* @hb: The destination hash bucket
*
* The hb->lock must be held by the caller, and is released here. A call to
* queue_me() is typically paired with exactly one call to unqueue_me(). The
* exceptions involve the PI related operations, which may use unqueue_me_pi()
* or nothing if the unqueue is done as part of the wake process and the unqueue
* state is implicit in the state of woken task (see futex_wait_requeue_pi() for
* an example).
*/
static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
__releases(&hb->lock)
{
__queue_me(q, hb);
spin_unlock(&hb->lock);
}
@ -2125,10 +2217,13 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
{
u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
struct futex_pi_state *pi_state = q->pi_state;
struct task_struct *oldowner = pi_state->owner;
u32 uval, uninitialized_var(curval), newval;
struct task_struct *oldowner;
int ret;
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
oldowner = pi_state->owner;
/* Owner died? */
if (!pi_state->owner)
newtid |= FUTEX_OWNER_DIED;
@ -2136,7 +2231,8 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
/*
* We are here either because we stole the rtmutex from the
* previous highest priority waiter or we are the highest priority
* waiter but failed to get the rtmutex the first time.
* waiter but have failed to get the rtmutex the first time.
*
* We have to replace the newowner TID in the user space variable.
* This must be atomic as we have to preserve the owner died bit here.
*
@ -2144,17 +2240,16 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
* because we can fault here. Imagine swapped out pages or a fork
* that marked all the anonymous memory readonly for cow.
*
* Modifying pi_state _before_ the user space value would
* leave the pi_state in an inconsistent state when we fault
* here, because we need to drop the hash bucket lock to
* handle the fault. This might be observed in the PID check
* in lookup_pi_state.
* Modifying pi_state _before_ the user space value would leave the
* pi_state in an inconsistent state when we fault here, because we
* need to drop the locks to handle the fault. This might be observed
* in the PID check in lookup_pi_state.
*/
retry:
if (get_futex_value_locked(&uval, uaddr))
goto handle_fault;
while (1) {
for (;;) {
newval = (uval & FUTEX_OWNER_DIED) | newtid;
if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval))
@ -2169,47 +2264,60 @@ retry:
* itself.
*/
if (pi_state->owner != NULL) {
raw_spin_lock_irq(&pi_state->owner->pi_lock);
raw_spin_lock(&pi_state->owner->pi_lock);
WARN_ON(list_empty(&pi_state->list));
list_del_init(&pi_state->list);
raw_spin_unlock_irq(&pi_state->owner->pi_lock);
raw_spin_unlock(&pi_state->owner->pi_lock);
}
pi_state->owner = newowner;
raw_spin_lock_irq(&newowner->pi_lock);
raw_spin_lock(&newowner->pi_lock);
WARN_ON(!list_empty(&pi_state->list));
list_add(&pi_state->list, &newowner->pi_state_list);
raw_spin_unlock_irq(&newowner->pi_lock);
raw_spin_unlock(&newowner->pi_lock);
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
return 0;
/*
* To handle the page fault we need to drop the hash bucket
* lock here. That gives the other task (either the highest priority
* waiter itself or the task which stole the rtmutex) the
* chance to try the fixup of the pi_state. So once we are
* back from handling the fault we need to check the pi_state
* after reacquiring the hash bucket lock and before trying to
* do another fixup. When the fixup has been done already we
* simply return.
* To handle the page fault we need to drop the locks here. That gives
* the other task (either the highest priority waiter itself or the
* task which stole the rtmutex) the chance to try the fixup of the
* pi_state. So once we are back from handling the fault we need to
* check the pi_state after reacquiring the locks and before trying to
* do another fixup. When the fixup has been done already we simply
* return.
*
* Note: we hold both hb->lock and pi_mutex->wait_lock. We can safely
* drop hb->lock since the caller owns the hb -> futex_q relation.
* Dropping the pi_mutex->wait_lock requires the state revalidate.
*/
handle_fault:
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
spin_unlock(q->lock_ptr);
ret = fault_in_user_writeable(uaddr);
spin_lock(q->lock_ptr);
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
/*
* Check if someone else fixed it for us:
*/
if (pi_state->owner != oldowner)
return 0;
if (pi_state->owner != oldowner) {
ret = 0;
goto out_unlock;
}
if (ret)
return ret;
goto out_unlock;
goto retry;
out_unlock:
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
return ret;
}
static long futex_wait_restart(struct restart_block *restart);
@ -2231,57 +2339,32 @@ static long futex_wait_restart(struct restart_block *restart);
*/
static int fixup_owner(u32 __user *uaddr, struct futex_q *q, int locked)
{
struct task_struct *owner;
int ret = 0;
if (locked) {
/*
* Got the lock. We might not be the anticipated owner if we
* did a lock-steal - fix up the PI-state in that case:
*
* We can safely read pi_state->owner without holding wait_lock
* because we now own the rt_mutex, only the owner will attempt
* to change it.
*/
if (q->pi_state->owner != current)
ret = fixup_pi_state_owner(uaddr, q, current);
goto out;
}
/*
* Catch the rare case, where the lock was released when we were on the
* way back before we locked the hash bucket.
*/
if (q->pi_state->owner == current) {
/*
* Try to get the rt_mutex now. This might fail as some other
* task acquired the rt_mutex after we removed ourself from the
* rt_mutex waiters list.
*/
if (rt_mutex_trylock(&q->pi_state->pi_mutex)) {
locked = 1;
goto out;
}
/*
* pi_state is incorrect, some other task did a lock steal and
* we returned due to timeout or signal without taking the
* rt_mutex. Too late.
*/
raw_spin_lock_irq(&q->pi_state->pi_mutex.wait_lock);
owner = rt_mutex_owner(&q->pi_state->pi_mutex);
if (!owner)
owner = rt_mutex_next_owner(&q->pi_state->pi_mutex);
raw_spin_unlock_irq(&q->pi_state->pi_mutex.wait_lock);
ret = fixup_pi_state_owner(uaddr, q, owner);
goto out;
}
/*
* Paranoia check. If we did not take the lock, then we should not be
* the owner of the rt_mutex.
*/
if (rt_mutex_owner(&q->pi_state->pi_mutex) == current)
if (rt_mutex_owner(&q->pi_state->pi_mutex) == current) {
printk(KERN_ERR "fixup_owner: ret = %d pi-mutex: %p "
"pi-state %p\n", ret,
q->pi_state->pi_mutex.owner,
q->pi_state->owner);
}
out:
return ret ? ret : locked;
@ -2505,6 +2588,8 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
ktime_t *time, int trylock)
{
struct hrtimer_sleeper timeout, *to = NULL;
struct futex_pi_state *pi_state = NULL;
struct rt_mutex_waiter rt_waiter;
struct futex_hash_bucket *hb;
struct futex_q q = futex_q_init;
int res, ret;
@ -2557,24 +2642,67 @@ retry_private:
}
}
WARN_ON(!q.pi_state);
/*
* Only actually queue now that the atomic ops are done:
*/
queue_me(&q, hb);
__queue_me(&q, hb);
WARN_ON(!q.pi_state);
/*
* Block on the PI mutex:
*/
if (!trylock) {
ret = rt_mutex_timed_futex_lock(&q.pi_state->pi_mutex, to);
} else {
ret = rt_mutex_trylock(&q.pi_state->pi_mutex);
if (trylock) {
ret = rt_mutex_futex_trylock(&q.pi_state->pi_mutex);
/* Fixup the trylock return value: */
ret = ret ? 0 : -EWOULDBLOCK;
goto no_block;
}
rt_mutex_init_waiter(&rt_waiter);
/*
* On PREEMPT_RT_FULL, when hb->lock becomes an rt_mutex, we must not
* hold it while doing rt_mutex_start_proxy(), because then it will
* include hb->lock in the blocking chain, even through we'll not in
* fact hold it while blocking. This will lead it to report -EDEADLK
* and BUG when futex_unlock_pi() interleaves with this.
*
* Therefore acquire wait_lock while holding hb->lock, but drop the
* latter before calling rt_mutex_start_proxy_lock(). This still fully
* serializes against futex_unlock_pi() as that does the exact same
* lock handoff sequence.
*/
raw_spin_lock_irq(&q.pi_state->pi_mutex.wait_lock);
spin_unlock(q.lock_ptr);
ret = __rt_mutex_start_proxy_lock(&q.pi_state->pi_mutex, &rt_waiter, current);
raw_spin_unlock_irq(&q.pi_state->pi_mutex.wait_lock);
if (ret) {
if (ret == 1)
ret = 0;
spin_lock(q.lock_ptr);
goto no_block;
}
if (unlikely(to))
hrtimer_start_expires(&to->timer, HRTIMER_MODE_ABS);
ret = rt_mutex_wait_proxy_lock(&q.pi_state->pi_mutex, to, &rt_waiter);
spin_lock(q.lock_ptr);
/*
* If we failed to acquire the lock (signal/timeout), we must
* first acquire the hb->lock before removing the lock from the
* rt_mutex waitqueue, such that we can keep the hb and rt_mutex
* wait lists consistent.
*
* In particular; it is important that futex_unlock_pi() can not
* observe this inconsistency.
*/
if (ret && !rt_mutex_cleanup_proxy_lock(&q.pi_state->pi_mutex, &rt_waiter))
ret = 0;
no_block:
/*
* Fixup the pi_state owner and possibly acquire the lock if we
* haven't already.
@ -2591,12 +2719,19 @@ retry_private:
* If fixup_owner() faulted and was unable to handle the fault, unlock
* it and return the fault to userspace.
*/
if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current))
rt_mutex_unlock(&q.pi_state->pi_mutex);
if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current)) {
pi_state = q.pi_state;
get_pi_state(pi_state);
}
/* Unqueue and drop the lock */
unqueue_me_pi(&q);
if (pi_state) {
rt_mutex_futex_unlock(&pi_state->pi_mutex);
put_pi_state(pi_state);
}
goto out_put_key;
out_unlock_put_key:
@ -2605,8 +2740,10 @@ out_unlock_put_key:
out_put_key:
put_futex_key(&q.key);
out:
if (to)
if (to) {
hrtimer_cancel(&to->timer);
destroy_hrtimer_on_stack(&to->timer);
}
return ret != -EINTR ? ret : -ERESTARTNOINTR;
uaddr_faulted:
@ -2633,7 +2770,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
u32 uninitialized_var(curval), uval, vpid = task_pid_vnr(current);
union futex_key key = FUTEX_KEY_INIT;
struct futex_hash_bucket *hb;
struct futex_q *match;
struct futex_q *top_waiter;
int ret;
retry:
@ -2657,12 +2794,37 @@ retry:
* all and we at least want to know if user space fiddled
* with the futex value instead of blindly unlocking.
*/
match = futex_top_waiter(hb, &key);
if (match) {
ret = wake_futex_pi(uaddr, uval, match, hb);
top_waiter = futex_top_waiter(hb, &key);
if (top_waiter) {
struct futex_pi_state *pi_state = top_waiter->pi_state;
ret = -EINVAL;
if (!pi_state)
goto out_unlock;
/*
* In case of success wake_futex_pi dropped the hash
* bucket lock.
* If current does not own the pi_state then the futex is
* inconsistent and user space fiddled with the futex value.
*/
if (pi_state->owner != current)
goto out_unlock;
get_pi_state(pi_state);
/*
* By taking wait_lock while still holding hb->lock, we ensure
* there is no point where we hold neither; and therefore
* wake_futex_pi() must observe a state consistent with what we
* observed.
*/
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
spin_unlock(&hb->lock);
ret = wake_futex_pi(uaddr, uval, pi_state);
put_pi_state(pi_state);
/*
* Success, we're done! No tricky corner cases.
*/
if (!ret)
goto out_putkey;
@ -2677,7 +2839,6 @@ retry:
* setting the FUTEX_WAITERS bit. Try again.
*/
if (ret == -EAGAIN) {
spin_unlock(&hb->lock);
put_futex_key(&key);
goto retry;
}
@ -2685,7 +2846,7 @@ retry:
* wake_futex_pi has detected invalid state. Tell user
* space.
*/
goto out_unlock;
goto out_putkey;
}
/*
@ -2695,8 +2856,10 @@ retry:
* preserve the WAITERS bit not the OWNER_DIED one. We are the
* owner.
*/
if (cmpxchg_futex_value_locked(&curval, uaddr, uval, 0))
if (cmpxchg_futex_value_locked(&curval, uaddr, uval, 0)) {
spin_unlock(&hb->lock);
goto pi_faulted;
}
/*
* If uval has changed, let user space handle it.
@ -2710,7 +2873,6 @@ out_putkey:
return ret;
pi_faulted:
spin_unlock(&hb->lock);
put_futex_key(&key);
ret = fault_in_user_writeable(uaddr);
@ -2814,6 +2976,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
u32 __user *uaddr2)
{
struct hrtimer_sleeper timeout, *to = NULL;
struct futex_pi_state *pi_state = NULL;
struct rt_mutex_waiter rt_waiter;
struct futex_hash_bucket *hb;
union futex_key key2 = FUTEX_KEY_INIT;
@ -2840,10 +3003,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
* The waiter is allocated on our stack, manipulated by the requeue
* code while we sleep on uaddr.
*/
debug_rt_mutex_init_waiter(&rt_waiter);
RB_CLEAR_NODE(&rt_waiter.pi_tree_entry);
RB_CLEAR_NODE(&rt_waiter.tree_entry);
rt_waiter.task = NULL;
rt_mutex_init_waiter(&rt_waiter);
ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE);
if (unlikely(ret != 0))
@ -2898,8 +3058,10 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
if (q.pi_state && (q.pi_state->owner != current)) {
spin_lock(q.lock_ptr);
ret = fixup_pi_state_owner(uaddr2, &q, current);
if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current)
rt_mutex_unlock(&q.pi_state->pi_mutex);
if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current) {
pi_state = q.pi_state;
get_pi_state(pi_state);
}
/*
* Drop the reference to the pi state which
* the requeue_pi() code acquired for us.
@ -2917,10 +3079,13 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
*/
WARN_ON(!q.pi_state);
pi_mutex = &q.pi_state->pi_mutex;
ret = rt_mutex_finish_proxy_lock(pi_mutex, to, &rt_waiter);
debug_rt_mutex_free_waiter(&rt_waiter);
ret = rt_mutex_wait_proxy_lock(pi_mutex, to, &rt_waiter);
spin_lock(q.lock_ptr);
if (ret && !rt_mutex_cleanup_proxy_lock(pi_mutex, &rt_waiter))
ret = 0;
debug_rt_mutex_free_waiter(&rt_waiter);
/*
* Fixup the pi_state owner and possibly acquire the lock if we
* haven't already.
@ -2938,13 +3103,20 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
* the fault, unlock the rt_mutex and return the fault to
* userspace.
*/
if (ret && rt_mutex_owner(pi_mutex) == current)
rt_mutex_unlock(pi_mutex);
if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current) {
pi_state = q.pi_state;
get_pi_state(pi_state);
}
/* Unqueue and drop the lock. */
unqueue_me_pi(&q);
}
if (pi_state) {
rt_mutex_futex_unlock(&pi_state->pi_mutex);
put_pi_state(pi_state);
}
if (ret == -EINTR) {
/*
* We've already been requeued, but cannot restart by calling

242
kernel/locking/lockdep.c
View File

@ -660,6 +660,7 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
struct lockdep_subclass_key *key;
struct hlist_head *hash_head;
struct lock_class *class;
bool is_static = false;
if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
debug_locks_off();
@ -673,10 +674,23 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
/*
* Static locks do not have their class-keys yet - for them the key
* is the lock object itself:
* is the lock object itself. If the lock is in the per cpu area,
* the canonical address of the lock (per cpu offset removed) is
* used.
*/
if (unlikely(!lock->key))
lock->key = (void *)lock;
if (unlikely(!lock->key)) {
unsigned long can_addr, addr = (unsigned long)lock;
if (__is_kernel_percpu_address(addr, &can_addr))
lock->key = (void *)can_addr;
else if (__is_module_percpu_address(addr, &can_addr))
lock->key = (void *)can_addr;
else if (static_obj(lock))
lock->key = (void *)lock;
else
return ERR_PTR(-EINVAL);
is_static = true;
}
/*
* NOTE: the class-key must be unique. For dynamic locks, a static
@ -708,7 +722,7 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
}
}
return NULL;
return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL);
}
/*
@ -726,19 +740,18 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
DEBUG_LOCKS_WARN_ON(!irqs_disabled());
class = look_up_lock_class(lock, subclass);
if (likely(class))
if (likely(!IS_ERR_OR_NULL(class)))
goto out_set_class_cache;
/*
* Debug-check: all keys must be persistent!
*/
if (!static_obj(lock->key)) {
*/
if (IS_ERR(class)) {
debug_locks_off();
printk("INFO: trying to register non-static key.\n");
printk("the code is fine but needs lockdep annotation.\n");
printk("turning off the locking correctness validator.\n");
dump_stack();
return NULL;
}
@ -3419,7 +3432,7 @@ static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
* Clearly if the lock hasn't been acquired _ever_, we're not
* holding it either, so report failure.
*/
if (!class)
if (IS_ERR_OR_NULL(class))
return 0;
/*
@ -3437,13 +3450,67 @@ static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
return 0;
}
/* @depth must not be zero */
static struct held_lock *find_held_lock(struct task_struct *curr,
struct lockdep_map *lock,
unsigned int depth, int *idx)
{
struct held_lock *ret, *hlock, *prev_hlock;
int i;
i = depth - 1;
hlock = curr->held_locks + i;
ret = hlock;
if (match_held_lock(hlock, lock))
goto out;
ret = NULL;
for (i--, prev_hlock = hlock--;
i >= 0;
i--, prev_hlock = hlock--) {
/*
* We must not cross into another context:
*/
if (prev_hlock->irq_context != hlock->irq_context) {
ret = NULL;
break;
}
if (match_held_lock(hlock, lock)) {
ret = hlock;
break;
}
}
out:
*idx = i;
return ret;
}
static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
int idx)
{
struct held_lock *hlock;
for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
if (!__lock_acquire(hlock->instance,
hlock_class(hlock)->subclass,
hlock->trylock,
hlock->read, hlock->check,
hlock->hardirqs_off,
hlock->nest_lock, hlock->acquire_ip,
hlock->references, hlock->pin_count))
return 1;
}
return 0;
}
static int
__lock_set_class(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, unsigned int subclass,
unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock, *prev_hlock;
struct held_lock *hlock;
struct lock_class *class;
unsigned int depth;
int i;
@ -3456,21 +3523,10 @@ __lock_set_class(struct lockdep_map *lock, const char *name,
if (DEBUG_LOCKS_WARN_ON(!depth))
return 0;
prev_hlock = NULL;
for (i = depth-1; i >= 0; i--) {
hlock = curr->held_locks + i;
/*
* We must not cross into another context:
*/
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
break;
if (match_held_lock(hlock, lock))
goto found_it;
prev_hlock = hlock;
}
return print_unlock_imbalance_bug(curr, lock, ip);
hlock = find_held_lock(curr, lock, depth, &i);
if (!hlock)
return print_unlock_imbalance_bug(curr, lock, ip);
found_it:
lockdep_init_map(lock, name, key, 0);
class = register_lock_class(lock, subclass, 0);
hlock->class_idx = class - lock_classes + 1;
@ -3478,15 +3534,46 @@ found_it:
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
for (; i < depth; i++) {
hlock = curr->held_locks + i;
if (!__lock_acquire(hlock->instance,
hlock_class(hlock)->subclass, hlock->trylock,
hlock->read, hlock->check, hlock->hardirqs_off,
hlock->nest_lock, hlock->acquire_ip,
hlock->references, hlock->pin_count))
return 0;
}
if (reacquire_held_locks(curr, depth, i))
return 0;
/*
* I took it apart and put it back together again, except now I have
* these 'spare' parts.. where shall I put them.
*/
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
return 0;
return 1;
}
static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock;
unsigned int depth;
int i;
depth = curr->lockdep_depth;
/*
* This function is about (re)setting the class of a held lock,
* yet we're not actually holding any locks. Naughty user!
*/
if (DEBUG_LOCKS_WARN_ON(!depth))
return 0;
hlock = find_held_lock(curr, lock, depth, &i);
if (!hlock)
return print_unlock_imbalance_bug(curr, lock, ip);
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
WARN(hlock->read, "downgrading a read lock");
hlock->read = 1;
hlock->acquire_ip = ip;
if (reacquire_held_locks(curr, depth, i))
return 0;
/*
* I took it apart and put it back together again, except now I have
@ -3508,7 +3595,7 @@ static int
__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock, *prev_hlock;
struct held_lock *hlock;
unsigned int depth;
int i;
@ -3527,21 +3614,10 @@ __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
* Check whether the lock exists in the current stack
* of held locks:
*/
prev_hlock = NULL;
for (i = depth-1; i >= 0; i--) {
hlock = curr->held_locks + i;
/*
* We must not cross into another context:
*/
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
break;
if (match_held_lock(hlock, lock))
goto found_it;
prev_hlock = hlock;
}
return print_unlock_imbalance_bug(curr, lock, ip);
hlock = find_held_lock(curr, lock, depth, &i);
if (!hlock)
return print_unlock_imbalance_bug(curr, lock, ip);
found_it:
if (hlock->instance == lock)
lock_release_holdtime(hlock);
@ -3568,15 +3644,8 @@ found_it:
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
for (i++; i < depth; i++) {
hlock = curr->held_locks + i;
if (!__lock_acquire(hlock->instance,
hlock_class(hlock)->subclass, hlock->trylock,
hlock->read, hlock->check, hlock->hardirqs_off,
hlock->nest_lock, hlock->acquire_ip,
hlock->references, hlock->pin_count))
return 0;
}
if (reacquire_held_locks(curr, depth, i + 1))
return 0;
/*
* We had N bottles of beer on the wall, we drank one, but now
@ -3741,6 +3810,23 @@ void lock_set_class(struct lockdep_map *lock, const char *name,
}
EXPORT_SYMBOL_GPL(lock_set_class);
void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
{
unsigned long flags;
if (unlikely(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
current->lockdep_recursion = 1;
check_flags(flags);
if (__lock_downgrade(lock, ip))
check_chain_key(current);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_downgrade);
/*
* We are not always called with irqs disabled - do that here,
* and also avoid lockdep recursion:
@ -3903,7 +3989,7 @@ static void
__lock_contended(struct lockdep_map *lock, unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock, *prev_hlock;
struct held_lock *hlock;
struct lock_class_stats *stats;
unsigned int depth;
int i, contention_point, contending_point;
@ -3916,22 +4002,12 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
if (DEBUG_LOCKS_WARN_ON(!depth))
return;
prev_hlock = NULL;
for (i = depth-1; i >= 0; i--) {
hlock = curr->held_locks + i;
/*
* We must not cross into another context:
*/
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
break;
if (match_held_lock(hlock, lock))
goto found_it;
prev_hlock = hlock;
hlock = find_held_lock(curr, lock, depth, &i);
if (!hlock) {
print_lock_contention_bug(curr, lock, ip);
return;
}
print_lock_contention_bug(curr, lock, ip);
return;
found_it:
if (hlock->instance != lock)
return;
@ -3955,7 +4031,7 @@ static void
__lock_acquired(struct lockdep_map *lock, unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock, *prev_hlock;
struct held_lock *hlock;
struct lock_class_stats *stats;
unsigned int depth;
u64 now, waittime = 0;
@ -3969,22 +4045,12 @@ __lock_acquired(struct lockdep_map *lock, unsigned long ip)
if (DEBUG_LOCKS_WARN_ON(!depth))
return;
prev_hlock = NULL;
for (i = depth-1; i >= 0; i--) {
hlock = curr->held_locks + i;
/*
* We must not cross into another context:
*/
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
break;
if (match_held_lock(hlock, lock))
goto found_it;
prev_hlock = hlock;
hlock = find_held_lock(curr, lock, depth, &i);
if (!hlock) {
print_lock_contention_bug(curr, lock, _RET_IP_);
return;
}
print_lock_contention_bug(curr, lock, _RET_IP_);
return;
found_it:
if (hlock->instance != lock)
return;
@ -4172,7 +4238,7 @@ void lockdep_reset_lock(struct lockdep_map *lock)
* If the class exists we look it up and zap it:
*/
class = look_up_lock_class(lock, j);
if (class)
if (!IS_ERR_OR_NULL(class))
zap_class(class);
}
/*

9
kernel/locking/rtmutex-debug.c
View File

@ -174,12 +174,3 @@ void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
lock->name = name;
}
void
rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
{
}
void rt_mutex_deadlock_account_unlock(struct task_struct *task)
{
}

3
kernel/locking/rtmutex-debug.h
View File

@ -9,9 +9,6 @@
* This file contains macros used solely by rtmutex.c. Debug version.
*/
extern void
rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task);
extern void rt_mutex_deadlock_account_unlock(struct task_struct *task);
extern void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
extern void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter);
extern void debug_rt_mutex_init(struct rt_mutex *lock, const char *name);

398
kernel/locking/rtmutex.c
View File

@ -224,6 +224,12 @@ static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
}
#endif
/*
* Only use with rt_mutex_waiter_{less,equal}()
*/
#define task_to_waiter(p) \
&(struct rt_mutex_waiter){ .prio = (p)->prio, .deadline = (p)->dl.deadline }
static inline int
rt_mutex_waiter_less(struct rt_mutex_waiter *left,
struct rt_mutex_waiter *right)
@ -238,12 +244,30 @@ rt_mutex_waiter_less(struct rt_mutex_waiter *left,
* then right waiter has a dl_prio() too.
*/
if (dl_prio(left->prio))
return dl_time_before(left->task->dl.deadline,
right->task->dl.deadline);
return dl_time_before(left->deadline, right->deadline);
return 0;
}
static inline int
rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
struct rt_mutex_waiter *right)
{
if (left->prio != right->prio)
return 0;
/*
* If both waiters have dl_prio(), we check the deadlines of the
* associated tasks.
* If left waiter has a dl_prio(), and we didn't return 0 above,
* then right waiter has a dl_prio() too.
*/
if (dl_prio(left->prio))
return left->deadline == right->deadline;
return 1;
}
static void
rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
{
@ -322,72 +346,16 @@ rt_mutex_dequeue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
RB_CLEAR_NODE(&waiter->pi_tree_entry);
}
/*
* Calculate task priority from the waiter tree priority
*
* Return task->normal_prio when the waiter tree is empty or when
* the waiter is not allowed to do priority boosting
*/
int rt_mutex_getprio(struct task_struct *task)
static void rt_mutex_adjust_prio(struct task_struct *p)
{
if (likely(!task_has_pi_waiters(task)))
return task->normal_prio;
struct task_struct *pi_task = NULL;
return min(task_top_pi_waiter(task)->prio,
task->normal_prio);
}
lockdep_assert_held(&p->pi_lock);
struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
{
if (likely(!task_has_pi_waiters(task)))
return NULL;
if (task_has_pi_waiters(p))
pi_task = task_top_pi_waiter(p)->task;
return task_top_pi_waiter(task)->task;
}
/*
* Called by sched_setscheduler() to get the priority which will be
* effective after the change.
*/
int rt_mutex_get_effective_prio(struct task_struct *task, int newprio)
{
if (!task_has_pi_waiters(task))
return newprio;
if (task_top_pi_waiter(task)->task->prio <= newprio)
return task_top_pi_waiter(task)->task->prio;
return newprio;
}
/*
* Adjust the priority of a task, after its pi_waiters got modified.
*
* This can be both boosting and unboosting. task->pi_lock must be held.
*/
static void __rt_mutex_adjust_prio(struct task_struct *task)
{
int prio = rt_mutex_getprio(task);
if (task->prio != prio || dl_prio(prio))
rt_mutex_setprio(task, prio);
}
/*
* Adjust task priority (undo boosting). Called from the exit path of
* rt_mutex_slowunlock() and rt_mutex_slowlock().
*
* (Note: We do this outside of the protection of lock->wait_lock to
* allow the lock to be taken while or before we readjust the priority
* of task. We do not use the spin_xx_mutex() variants here as we are
* outside of the debug path.)
*/
void rt_mutex_adjust_prio(struct task_struct *task)
{
unsigned long flags;
raw_spin_lock_irqsave(&task->pi_lock, flags);
__rt_mutex_adjust_prio(task);
raw_spin_unlock_irqrestore(&task->pi_lock, flags);
rt_mutex_setprio(p, pi_task);
}
/*
@ -610,7 +578,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
* enabled we continue, but stop the requeueing in the chain
* walk.
*/
if (waiter->prio == task->prio) {
if (rt_mutex_waiter_equal(waiter, task_to_waiter(task))) {
if (!detect_deadlock)
goto out_unlock_pi;
else
@ -706,7 +674,26 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
/* [7] Requeue the waiter in the lock waiter tree. */
rt_mutex_dequeue(lock, waiter);
/*
* Update the waiter prio fields now that we're dequeued.
*
* These values can have changed through either:
*
* sys_sched_set_scheduler() / sys_sched_setattr()
*
* or
*
* DL CBS enforcement advancing the effective deadline.
*
* Even though pi_waiters also uses these fields, and that tree is only
* updated in [11], we can do this here, since we hold [L], which
* serializes all pi_waiters access and rb_erase() does not care about
* the values of the node being removed.
*/
waiter->prio = task->prio;
waiter->deadline = task->dl.deadline;
rt_mutex_enqueue(lock, waiter);
/* [8] Release the task */
@ -747,7 +734,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
*/
rt_mutex_dequeue_pi(task, prerequeue_top_waiter);
rt_mutex_enqueue_pi(task, waiter);
__rt_mutex_adjust_prio(task);
rt_mutex_adjust_prio(task);
} else if (prerequeue_top_waiter == waiter) {
/*
@ -763,7 +750,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
rt_mutex_dequeue_pi(task, waiter);
waiter = rt_mutex_top_waiter(lock);
rt_mutex_enqueue_pi(task, waiter);
__rt_mutex_adjust_prio(task);
rt_mutex_adjust_prio(task);
} else {
/*
* Nothing changed. No need to do any priority
@ -833,6 +820,8 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
struct rt_mutex_waiter *waiter)
{
lockdep_assert_held(&lock->wait_lock);
/*
* Before testing whether we can acquire @lock, we set the
* RT_MUTEX_HAS_WAITERS bit in @lock->owner. This forces all
@ -892,7 +881,8 @@ static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
* the top waiter priority (kernel view),
* @task lost.
*/
if (task->prio >= rt_mutex_top_waiter(lock)->prio)
if (!rt_mutex_waiter_less(task_to_waiter(task),
rt_mutex_top_waiter(lock)))
return 0;
/*
@ -938,8 +928,6 @@ takeit:
*/
rt_mutex_set_owner(lock, task);
rt_mutex_deadlock_account_lock(lock, task);
return 1;
}
@ -960,6 +948,8 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
struct rt_mutex *next_lock;
int chain_walk = 0, res;
lockdep_assert_held(&lock->wait_lock);
/*
* Early deadlock detection. We really don't want the task to
* enqueue on itself just to untangle the mess later. It's not
@ -973,10 +963,11 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
return -EDEADLK;
raw_spin_lock(&task->pi_lock);
__rt_mutex_adjust_prio(task);
rt_mutex_adjust_prio(task);
waiter->task = task;
waiter->lock = lock;
waiter->prio = task->prio;
waiter->deadline = task->dl.deadline;
/* Get the top priority waiter on the lock */
if (rt_mutex_has_waiters(lock))
@ -995,7 +986,7 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
rt_mutex_dequeue_pi(owner, top_waiter);
rt_mutex_enqueue_pi(owner, waiter);
__rt_mutex_adjust_prio(owner);
rt_mutex_adjust_prio(owner);
if (owner->pi_blocked_on)
chain_walk = 1;
} else if (rt_mutex_cond_detect_deadlock(waiter, chwalk)) {
@ -1047,12 +1038,14 @@ static void mark_wakeup_next_waiter(struct wake_q_head *wake_q,
waiter = rt_mutex_top_waiter(lock);
/*
* Remove it from current->pi_waiters. We do not adjust a
* possible priority boost right now. We execute wakeup in the
* boosted mode and go back to normal after releasing
* lock->wait_lock.
* Remove it from current->pi_waiters and deboost.
*
* We must in fact deboost here in order to ensure we call
* rt_mutex_setprio() to update p->pi_top_task before the
* task unblocks.
*/
rt_mutex_dequeue_pi(current, waiter);
rt_mutex_adjust_prio(current);
/*
* As we are waking up the top waiter, and the waiter stays
@ -1064,9 +1057,19 @@ static void mark_wakeup_next_waiter(struct wake_q_head *wake_q,
*/
lock->owner = (void *) RT_MUTEX_HAS_WAITERS;
raw_spin_unlock(&current->pi_lock);
/*
* We deboosted before waking the top waiter task such that we don't
* run two tasks with the 'same' priority (and ensure the
* p->pi_top_task pointer points to a blocked task). This however can
* lead to priority inversion if we would get preempted after the
* deboost but before waking our donor task, hence the preempt_disable()
* before unlock.
*
* Pairs with preempt_enable() in rt_mutex_postunlock();
*/
preempt_disable();
wake_q_add(wake_q, waiter->task);
raw_spin_unlock(&current->pi_lock);
}
/*
@ -1082,6 +1085,8 @@ static void remove_waiter(struct rt_mutex *lock,
struct task_struct *owner = rt_mutex_owner(lock);
struct rt_mutex *next_lock;
lockdep_assert_held(&lock->wait_lock);
raw_spin_lock(&current->pi_lock);
rt_mutex_dequeue(lock, waiter);
current->pi_blocked_on = NULL;
@ -1101,7 +1106,7 @@ static void remove_waiter(struct rt_mutex *lock,
if (rt_mutex_has_waiters(lock))
rt_mutex_enqueue_pi(owner, rt_mutex_top_waiter(lock));
__rt_mutex_adjust_prio(owner);
rt_mutex_adjust_prio(owner);
/* Store the lock on which owner is blocked or NULL */
next_lock = task_blocked_on_lock(owner);
@ -1140,8 +1145,7 @@ void rt_mutex_adjust_pi(struct task_struct *task)
raw_spin_lock_irqsave(&task->pi_lock, flags);
waiter = task->pi_blocked_on;
if (!waiter || (waiter->prio == task->prio &&
!dl_prio(task->prio))) {
if (!waiter || rt_mutex_waiter_equal(waiter, task_to_waiter(task))) {
raw_spin_unlock_irqrestore(&task->pi_lock, flags);
return;
}
@ -1155,6 +1159,14 @@ void rt_mutex_adjust_pi(struct task_struct *task)
next_lock, NULL, task);
}
void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
{
debug_rt_mutex_init_waiter(waiter);
RB_CLEAR_NODE(&waiter->pi_tree_entry);
RB_CLEAR_NODE(&waiter->tree_entry);
waiter->task = NULL;
}
/**
* __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop
* @lock: the rt_mutex to take
@ -1237,9 +1249,7 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
unsigned long flags;
int ret = 0;
debug_rt_mutex_init_waiter(&waiter);
RB_CLEAR_NODE(&waiter.pi_tree_entry);
RB_CLEAR_NODE(&waiter.tree_entry);
rt_mutex_init_waiter(&waiter);
/*
* Technically we could use raw_spin_[un]lock_irq() here, but this can
@ -1330,7 +1340,8 @@ static inline int rt_mutex_slowtrylock(struct rt_mutex *lock)
/*
* Slow path to release a rt-mutex.
* Return whether the current task needs to undo a potential priority boosting.
*
* Return whether the current task needs to call rt_mutex_postunlock().
*/
static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,
struct wake_q_head *wake_q)
@ -1342,8 +1353,6 @@ static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,
debug_rt_mutex_unlock(lock);
rt_mutex_deadlock_account_unlock(current);
/*
* We must be careful here if the fast path is enabled. If we
* have no waiters queued we cannot set owner to NULL here
@ -1390,11 +1399,9 @@ static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,
* Queue the next waiter for wakeup once we release the wait_lock.
*/
mark_wakeup_next_waiter(wake_q, lock);
raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
/* check PI boosting */
return true;
return true; /* call rt_mutex_postunlock() */
}
/*
@ -1409,11 +1416,10 @@ rt_mutex_fastlock(struct rt_mutex *lock, int state,
struct hrtimer_sleeper *timeout,
enum rtmutex_chainwalk chwalk))
{
if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current))) {
rt_mutex_deadlock_account_lock(lock, current);
if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
return 0;
} else
return slowfn(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK);
return slowfn(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK);
}
static inline int
@ -1425,24 +1431,33 @@ rt_mutex_timed_fastlock(struct rt_mutex *lock, int state,
enum rtmutex_chainwalk chwalk))
{
if (chwalk == RT_MUTEX_MIN_CHAINWALK &&
likely(rt_mutex_cmpxchg_acquire(lock, NULL, current))) {
rt_mutex_deadlock_account_lock(lock, current);
likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
return 0;
} else
return slowfn(lock, state, timeout, chwalk);
return slowfn(lock, state, timeout, chwalk);
}
static inline int
rt_mutex_fasttrylock(struct rt_mutex *lock,
int (*slowfn)(struct rt_mutex *lock))
{
if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current))) {
rt_mutex_deadlock_account_lock(lock, current);
if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
return 1;
}
return slowfn(lock);
}
/*
* Performs the wakeup of the the top-waiter and re-enables preemption.
*/
void rt_mutex_postunlock(struct wake_q_head *wake_q)
{
wake_up_q(wake_q);
/* Pairs with preempt_disable() in rt_mutex_slowunlock() */
preempt_enable();
}
static inline void
rt_mutex_fastunlock(struct rt_mutex *lock,
bool (*slowfn)(struct rt_mutex *lock,
@ -1450,18 +1465,11 @@ rt_mutex_fastunlock(struct rt_mutex *lock,
{
DEFINE_WAKE_Q(wake_q);
if (likely(rt_mutex_cmpxchg_release(lock, current, NULL))) {
rt_mutex_deadlock_account_unlock(current);
if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))
return;
} else {
bool deboost = slowfn(lock, &wake_q);
wake_up_q(&wake_q);
/* Undo pi boosting if necessary: */
if (deboost)
rt_mutex_adjust_prio(current);
}
if (slowfn(lock, &wake_q))
rt_mutex_postunlock(&wake_q);
}
/**
@ -1495,16 +1503,11 @@ int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock)
EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);
/*
* Futex variant with full deadlock detection.
* Futex variant, must not use fastpath.
*/
int rt_mutex_timed_futex_lock(struct rt_mutex *lock,
struct hrtimer_sleeper *timeout)
int __sched rt_mutex_futex_trylock(struct rt_mutex *lock)
{
might_sleep();
return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout,
RT_MUTEX_FULL_CHAINWALK,
rt_mutex_slowlock);
return rt_mutex_slowtrylock(lock);
}
/**
@ -1563,20 +1566,43 @@ void __sched rt_mutex_unlock(struct rt_mutex *lock)
EXPORT_SYMBOL_GPL(rt_mutex_unlock);
/**
* rt_mutex_futex_unlock - Futex variant of rt_mutex_unlock
* @lock: the rt_mutex to be unlocked
*
* Returns: true/false indicating whether priority adjustment is
* required or not.
* Futex variant, that since futex variants do not use the fast-path, can be
* simple and will not need to retry.
*/
bool __sched rt_mutex_futex_unlock(struct rt_mutex *lock,
struct wake_q_head *wqh)
bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock,
struct wake_q_head *wake_q)
{
if (likely(rt_mutex_cmpxchg_release(lock, current, NULL))) {
rt_mutex_deadlock_account_unlock(current);
return false;
lockdep_assert_held(&lock->wait_lock);
debug_rt_mutex_unlock(lock);
if (!rt_mutex_has_waiters(lock)) {
lock->owner = NULL;
return false; /* done */
}
return rt_mutex_slowunlock(lock, wqh);
/*
* We've already deboosted, mark_wakeup_next_waiter() will
* retain preempt_disabled when we drop the wait_lock, to
* avoid inversion prior to the wakeup. preempt_disable()
* therein pairs with rt_mutex_postunlock().
*/
mark_wakeup_next_waiter(wake_q, lock);
return true; /* call postunlock() */
}
void __sched rt_mutex_futex_unlock(struct rt_mutex *lock)
{
DEFINE_WAKE_Q(wake_q);
bool postunlock;
raw_spin_lock_irq(&lock->wait_lock);
postunlock = __rt_mutex_futex_unlock(lock, &wake_q);
raw_spin_unlock_irq(&lock->wait_lock);
if (postunlock)
rt_mutex_postunlock(&wake_q);
}
/**
@ -1637,7 +1663,6 @@ void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
__rt_mutex_init(lock, NULL);
debug_rt_mutex_proxy_lock(lock, proxy_owner);
rt_mutex_set_owner(lock, proxy_owner);
rt_mutex_deadlock_account_lock(lock, proxy_owner);
}
/**
@ -1657,7 +1682,37 @@ void rt_mutex_proxy_unlock(struct rt_mutex *lock,
{
debug_rt_mutex_proxy_unlock(lock);
rt_mutex_set_owner(lock, NULL);
rt_mutex_deadlock_account_unlock(proxy_owner);
}
int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter,
struct task_struct *task)
{
int ret;
if (try_to_take_rt_mutex(lock, task, NULL))
return 1;
/* We enforce deadlock detection for futexes */
ret = task_blocks_on_rt_mutex(lock, waiter, task,
RT_MUTEX_FULL_CHAINWALK);
if (ret && !rt_mutex_owner(lock)) {
/*
* Reset the return value. We might have
* returned with -EDEADLK and the owner
* released the lock while we were walking the
* pi chain. Let the waiter sort it out.
*/
ret = 0;
}
if (unlikely(ret))
remove_waiter(lock, waiter);
debug_rt_mutex_print_deadlock(waiter);
return ret;
}
/**
@ -1680,33 +1735,9 @@ int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
int ret;
raw_spin_lock_irq(&lock->wait_lock);
if (try_to_take_rt_mutex(lock, task, NULL)) {
raw_spin_unlock_irq(&lock->wait_lock);
return 1;
}
/* We enforce deadlock detection for futexes */
ret = task_blocks_on_rt_mutex(lock, waiter, task,
RT_MUTEX_FULL_CHAINWALK);
if (ret && !rt_mutex_owner(lock)) {
/*
* Reset the return value. We might have
* returned with -EDEADLK and the owner
* released the lock while we were walking the
* pi chain. Let the waiter sort it out.
*/
ret = 0;
}
if (unlikely(ret))
remove_waiter(lock, waiter);
ret = __rt_mutex_start_proxy_lock(lock, waiter, task);
raw_spin_unlock_irq(&lock->wait_lock);
debug_rt_mutex_print_deadlock(waiter);
return ret;
}
@ -1731,21 +1762,23 @@ struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock)
}
/**
* rt_mutex_finish_proxy_lock() - Complete lock acquisition
* rt_mutex_wait_proxy_lock() - Wait for lock acquisition
* @lock: the rt_mutex we were woken on
* @to: the timeout, null if none. hrtimer should already have
* been started.
* @waiter: the pre-initialized rt_mutex_waiter
*
* Complete the lock acquisition started our behalf by another thread.
* Wait for the the lock acquisition started on our behalf by
* rt_mutex_start_proxy_lock(). Upon failure, the caller must call
* rt_mutex_cleanup_proxy_lock().
*
* Returns:
* 0 - success
* <0 - error, one of -EINTR, -ETIMEDOUT
*
* Special API call for PI-futex requeue support
* Special API call for PI-futex support
*/
int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
struct hrtimer_sleeper *to,
struct rt_mutex_waiter *waiter)
{
@ -1758,8 +1791,45 @@ int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
/* sleep on the mutex */
ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
if (unlikely(ret))
raw_spin_unlock_irq(&lock->wait_lock);
return ret;
}
/**
* rt_mutex_cleanup_proxy_lock() - Cleanup failed lock acquisition
* @lock: the rt_mutex we were woken on
* @waiter: the pre-initialized rt_mutex_waiter
*
* Attempt to clean up after a failed rt_mutex_wait_proxy_lock().
*
* Unless we acquired the lock; we're still enqueued on the wait-list and can
* in fact still be granted ownership until we're removed. Therefore we can
* find we are in fact the owner and must disregard the
* rt_mutex_wait_proxy_lock() failure.
*
* Returns:
* true - did the cleanup, we done.
* false - we acquired the lock after rt_mutex_wait_proxy_lock() returned,
* caller should disregards its return value.
*
* Special API call for PI-futex support
*/
bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter)
{
bool cleanup = false;
raw_spin_lock_irq(&lock->wait_lock);
/*
* Unless we're the owner; we're still enqueued on the wait_list.
* So check if we became owner, if not, take us off the wait_list.
*/
if (rt_mutex_owner(lock) != current) {
remove_waiter(lock, waiter);
fixup_rt_mutex_waiters(lock);
cleanup = true;
}
/*
* try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
@ -1769,5 +1839,5 @@ int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
raw_spin_unlock_irq(&lock->wait_lock);
return ret;
return cleanup;
}

2
kernel/locking/rtmutex.h
View File

@ -11,8 +11,6 @@
*/
#define rt_mutex_deadlock_check(l) (0)
#define rt_mutex_deadlock_account_lock(m, t) do { } while (0)
#define rt_mutex_deadlock_account_unlock(l) do { } while (0)
#define debug_rt_mutex_init_waiter(w) do { } while (0)
#define debug_rt_mutex_free_waiter(w) do { } while (0)
#define debug_rt_mutex_lock(l) do { } while (0)

25
kernel/locking/rtmutex_common.h
View File

@ -34,6 +34,7 @@ struct rt_mutex_waiter {
struct rt_mutex *deadlock_lock;
#endif
int prio;
u64 deadline;
};
/*
@ -103,16 +104,26 @@ extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
struct task_struct *proxy_owner);
extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
struct task_struct *proxy_owner);
extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter,
struct task_struct *task);
extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter,
struct task_struct *task);
extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
struct hrtimer_sleeper *to,
struct rt_mutex_waiter *waiter);
extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
extern bool rt_mutex_futex_unlock(struct rt_mutex *lock,
struct wake_q_head *wqh);
extern void rt_mutex_adjust_prio(struct task_struct *task);
extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
struct hrtimer_sleeper *to,
struct rt_mutex_waiter *waiter);
extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
struct rt_mutex_waiter *waiter);
extern int rt_mutex_futex_trylock(struct rt_mutex *l);
extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
struct wake_q_head *wqh);
extern void rt_mutex_postunlock(struct wake_q_head *wake_q);
#ifdef CONFIG_DEBUG_RT_MUTEXES
# include "rtmutex-debug.h"

6
kernel/locking/rwsem.c
View File

@ -124,10 +124,8 @@ EXPORT_SYMBOL(up_write);
*/
void downgrade_write(struct rw_semaphore *sem)
{
/*
* lockdep: a downgraded write will live on as a write
* dependency.
*/
lock_downgrade(&sem->dep_map, _RET_IP_);
rwsem_set_reader_owned(sem);
__downgrade_write(sem);
}

29
kernel/locking/test-ww_mutex.c
View File

@ -353,8 +353,8 @@ static int test_cycle(unsigned int ncpus)
struct stress {
struct work_struct work;
struct ww_mutex *locks;
unsigned long timeout;
int nlocks;
int nloops;
};
static int *get_random_order(int count)
@ -398,12 +398,11 @@ static void stress_inorder_work(struct work_struct *work)
if (!order)
return;
ww_acquire_init(&ctx, &ww_class);
do {
int contended = -1;
int n, err;
ww_acquire_init(&ctx, &ww_class);
retry:
err = 0;
for (n = 0; n < nlocks; n++) {
@ -433,9 +432,9 @@ retry:
__func__, err);
break;
}
} while (--stress->nloops);
ww_acquire_fini(&ctx);
ww_acquire_fini(&ctx);
} while (!time_after(jiffies, stress->timeout));
kfree(order);
kfree(stress);
@ -470,9 +469,9 @@ static void stress_reorder_work(struct work_struct *work)
kfree(order);
order = NULL;
ww_acquire_init(&ctx, &ww_class);
do {
ww_acquire_init(&ctx, &ww_class);
list_for_each_entry(ll, &locks, link) {
err = ww_mutex_lock(ll->lock, &ctx);
if (!err)
@ -495,9 +494,9 @@ static void stress_reorder_work(struct work_struct *work)
dummy_load(stress);
list_for_each_entry(ll, &locks, link)
ww_mutex_unlock(ll->lock);
} while (--stress->nloops);
ww_acquire_fini(&ctx);
ww_acquire_fini(&ctx);
} while (!time_after(jiffies, stress->timeout));
out:
list_for_each_entry_safe(ll, ln, &locks, link)
@ -523,7 +522,7 @@ static void stress_one_work(struct work_struct *work)
__func__, err);
break;
}
} while (--stress->nloops);
} while (!time_after(jiffies, stress->timeout));
kfree(stress);
}
@ -533,7 +532,7 @@ static void stress_one_work(struct work_struct *work)
#define STRESS_ONE BIT(2)
#define STRESS_ALL (STRESS_INORDER | STRESS_REORDER | STRESS_ONE)
static int stress(int nlocks, int nthreads, int nloops, unsigned int flags)
static int stress(int nlocks, int nthreads, unsigned int flags)
{
struct ww_mutex *locks;
int n;
@ -575,7 +574,7 @@ static int stress(int nlocks, int nthreads, int nloops, unsigned int flags)
INIT_WORK(&stress->work, fn);
stress->locks = locks;
stress->nlocks = nlocks;
stress->nloops = nloops;
stress->timeout = jiffies + 2*HZ;
queue_work(wq, &stress->work);
nthreads--;
@ -619,15 +618,15 @@ static int __init test_ww_mutex_init(void)
if (ret)
return ret;
ret = stress(16, 2*ncpus, 1<<10, STRESS_INORDER);
ret = stress(16, 2*ncpus, STRESS_INORDER);
if (ret)
return ret;
ret = stress(16, 2*ncpus, 1<<10, STRESS_REORDER);
ret = stress(16, 2*ncpus, STRESS_REORDER);
if (ret)
return ret;
ret = stress(4095, hweight32(STRESS_ALL)*ncpus, 1<<12, STRESS_ALL);
ret = stress(4095, hweight32(STRESS_ALL)*ncpus, STRESS_ALL);
if (ret)
return ret;

40
kernel/module.c
View File

@ -665,16 +665,7 @@ static void percpu_modcopy(struct module *mod,
memcpy(per_cpu_ptr(mod->percpu, cpu), from, size);
}
/**
* is_module_percpu_address - test whether address is from module static percpu
* @addr: address to test
*
* Test whether @addr belongs to module static percpu area.
*
* RETURNS:
* %true if @addr is from module static percpu area
*/
bool is_module_percpu_address(unsigned long addr)
bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
{
struct module *mod;
unsigned int cpu;
@ -688,9 +679,15 @@ bool is_module_percpu_address(unsigned long addr)
continue;
for_each_possible_cpu(cpu) {
void *start = per_cpu_ptr(mod->percpu, cpu);
void *va = (void *)addr;
if ((void *)addr >= start &&
(void *)addr < start + mod->percpu_size) {
if (va >= start && va < start + mod->percpu_size) {
if (can_addr) {
*can_addr = (unsigned long) (va - start);
*can_addr += (unsigned long)
per_cpu_ptr(mod->percpu,
get_boot_cpu_id());
}
preempt_enable();
return true;
}
@ -701,6 +698,20 @@ bool is_module_percpu_address(unsigned long addr)
return false;
}
/**
* is_module_percpu_address - test whether address is from module static percpu
* @addr: address to test
*
* Test whether @addr belongs to module static percpu area.
*
* RETURNS:
* %true if @addr is from module static percpu area
*/
bool is_module_percpu_address(unsigned long addr)
{
return __is_module_percpu_address(addr, NULL);
}
#else /* ... !CONFIG_SMP */
static inline void __percpu *mod_percpu(struct module *mod)
@ -732,6 +743,11 @@ bool is_module_percpu_address(unsigned long addr)
return false;
}
bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
{
return false;
}
#endif /* CONFIG_SMP */
#define MODINFO_ATTR(field) \

64
kernel/sched/core.c
View File

@ -3671,10 +3671,25 @@ EXPORT_SYMBOL(default_wake_function);
#ifdef CONFIG_RT_MUTEXES
static inline int __rt_effective_prio(struct task_struct *pi_task, int prio)
{
if (pi_task)
prio = min(prio, pi_task->prio);
return prio;
}
static inline int rt_effective_prio(struct task_struct *p, int prio)
{
struct task_struct *pi_task = rt_mutex_get_top_task(p);
return __rt_effective_prio(pi_task, prio);
}
/*
* rt_mutex_setprio - set the current priority of a task
* @p: task
* @prio: prio value (kernel-internal form)
* @p: task to boost
* @pi_task: donor task
*
* This function changes the 'effective' priority of a task. It does
* not touch ->normal_prio like __setscheduler().
@ -3682,18 +3697,42 @@ EXPORT_SYMBOL(default_wake_function);
* Used by the rt_mutex code to implement priority inheritance
* logic. Call site only calls if the priority of the task changed.
*/
void rt_mutex_setprio(struct task_struct *p, int prio)
void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
{
int oldprio, queued, running, queue_flag =
int prio, oldprio, queued, running, queue_flag =
DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
const struct sched_class *prev_class;
struct rq_flags rf;
struct rq *rq;
BUG_ON(prio > MAX_PRIO);
/* XXX used to be waiter->prio, not waiter->task->prio */
prio = __rt_effective_prio(pi_task, p->normal_prio);
/*
* If nothing changed; bail early.
*/
if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio))
return;
rq = __task_rq_lock(p, &rf);
update_rq_clock(rq);
/*
* Set under pi_lock && rq->lock, such that the value can be used under
* either lock.
*
* Note that there is loads of tricky to make this pointer cache work
* right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to
* ensure a task is de-boosted (pi_task is set to NULL) before the
* task is allowed to run again (and can exit). This ensures the pointer
* points to a blocked task -- which guaratees the task is present.
*/
p->pi_top_task = pi_task;
/*
* For FIFO/RR we only need to set prio, if that matches we're done.
*/
if (prio == p->prio && !dl_prio(prio))
goto out_unlock;
/*
* Idle task boosting is a nono in general. There is one
@ -3713,7 +3752,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
goto out_unlock;
}
trace_sched_pi_setprio(p, prio);
trace_sched_pi_setprio(p, pi_task);
oldprio = p->prio;
if (oldprio == prio)
@ -3737,7 +3776,6 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
* running task
*/
if (dl_prio(prio)) {
struct task_struct *pi_task = rt_mutex_get_top_task(p);
if (!dl_prio(p->normal_prio) ||
(pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
p->dl.dl_boosted = 1;
@ -3775,6 +3813,11 @@ out_unlock:
balance_callback(rq);
preempt_enable();
}
#else
static inline int rt_effective_prio(struct task_struct *p, int prio)
{
return prio;
}
#endif
void set_user_nice(struct task_struct *p, long nice)
@ -4021,10 +4064,9 @@ static void __setscheduler(struct rq *rq, struct task_struct *p,
* Keep a potential priority boosting if called from
* sched_setscheduler().
*/
p->prio = normal_prio(p);
if (keep_boost)
p->prio = rt_mutex_get_effective_prio(p, normal_prio(p));
else
p->prio = normal_prio(p);
p->prio = rt_effective_prio(p, p->prio);
if (dl_prio(p->prio))
p->sched_class = &dl_sched_class;
@ -4311,7 +4353,7 @@ change:
* the runqueue. This will be done when the task deboost
* itself.
*/
new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
new_effective_prio = rt_effective_prio(p, newprio);
if (new_effective_prio == oldprio)
queue_flags &= ~DEQUEUE_MOVE;
}

169
lib/refcount.c
View File

@ -37,11 +37,29 @@
#include <linux/refcount.h>
#include <linux/bug.h>
/**
* refcount_add_not_zero - add a value to a refcount unless it is 0
* @i: the value to add to the refcount
* @r: the refcount
*
* Will saturate at UINT_MAX and WARN.
*
* Provides no memory ordering, it is assumed the caller has guaranteed the
* object memory to be stable (RCU, etc.). It does provide a control dependency
* and thereby orders future stores. See the comment on top.
*
* Use of this function is not recommended for the normal reference counting
* use case in which references are taken and released one at a time. In these
* cases, refcount_inc(), or one of its variants, should instead be used to
* increment a reference count.
*
* Return: false if the passed refcount is 0, true otherwise
*/
bool refcount_add_not_zero(unsigned int i, refcount_t *r)
{
unsigned int old, new, val = atomic_read(&r->refs);
unsigned int new, val = atomic_read(&r->refs);
for (;;) {
do {
if (!val)
return false;
@ -51,12 +69,8 @@ bool refcount_add_not_zero(unsigned int i, refcount_t *r)
new = val + i;
if (new < val)
new = UINT_MAX;
old = atomic_cmpxchg_relaxed(&r->refs, val, new);
if (old == val)
break;
val = old;
}
} while (!atomic_try_cmpxchg_relaxed(&r->refs, &val, new));
WARN_ONCE(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n");
@ -64,24 +78,45 @@ bool refcount_add_not_zero(unsigned int i, refcount_t *r)
}
EXPORT_SYMBOL_GPL(refcount_add_not_zero);
/**
* refcount_add - add a value to a refcount
* @i: the value to add to the refcount
* @r: the refcount
*
* Similar to atomic_add(), but will saturate at UINT_MAX and WARN.
*
* Provides no memory ordering, it is assumed the caller has guaranteed the
* object memory to be stable (RCU, etc.). It does provide a control dependency
* and thereby orders future stores. See the comment on top.
*
* Use of this function is not recommended for the normal reference counting
* use case in which references are taken and released one at a time. In these
* cases, refcount_inc(), or one of its variants, should instead be used to
* increment a reference count.
*/
void refcount_add(unsigned int i, refcount_t *r)
{
WARN_ONCE(!refcount_add_not_zero(i, r), "refcount_t: addition on 0; use-after-free.\n");
}
EXPORT_SYMBOL_GPL(refcount_add);
/*
* Similar to atomic_inc_not_zero(), will saturate at UINT_MAX and WARN.
/**
* refcount_inc_not_zero - increment a refcount unless it is 0
* @r: the refcount to increment
*
* Similar to atomic_inc_not_zero(), but will saturate at UINT_MAX and WARN.
*
* Provides no memory ordering, it is assumed the caller has guaranteed the
* object memory to be stable (RCU, etc.). It does provide a control dependency
* and thereby orders future stores. See the comment on top.
*
* Return: true if the increment was successful, false otherwise
*/
bool refcount_inc_not_zero(refcount_t *r)
{
unsigned int old, new, val = atomic_read(&r->refs);
unsigned int new, val = atomic_read(&r->refs);
for (;;) {
do {
new = val + 1;
if (!val)
@ -90,12 +125,7 @@ bool refcount_inc_not_zero(refcount_t *r)
if (unlikely(!new))
return true;
old = atomic_cmpxchg_relaxed(&r->refs, val, new);
if (old == val)
break;
val = old;
}
} while (!atomic_try_cmpxchg_relaxed(&r->refs, &val, new));
WARN_ONCE(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n");
@ -103,11 +133,17 @@ bool refcount_inc_not_zero(refcount_t *r)
}
EXPORT_SYMBOL_GPL(refcount_inc_not_zero);
/*
* Similar to atomic_inc(), will saturate at UINT_MAX and WARN.
/**
* refcount_inc - increment a refcount
* @r: the refcount to increment
*
* Similar to atomic_inc(), but will saturate at UINT_MAX and WARN.
*
* Provides no memory ordering, it is assumed the caller already has a
* reference on the object, will WARN when this is not so.
* reference on the object.
*
* Will WARN if the refcount is 0, as this represents a possible use-after-free
* condition.
*/
void refcount_inc(refcount_t *r)
{
@ -115,11 +151,31 @@ void refcount_inc(refcount_t *r)
}
EXPORT_SYMBOL_GPL(refcount_inc);
/**
* refcount_sub_and_test - subtract from a refcount and test if it is 0
* @i: amount to subtract from the refcount
* @r: the refcount
*
* Similar to atomic_dec_and_test(), but it will WARN, return false and
* ultimately leak on underflow and will fail to decrement when saturated
* at UINT_MAX.
*
* Provides release memory ordering, such that prior loads and stores are done
* before, and provides a control dependency such that free() must come after.
* See the comment on top.
*
* Use of this function is not recommended for the normal reference counting
* use case in which references are taken and released one at a time. In these
* cases, refcount_dec(), or one of its variants, should instead be used to
* decrement a reference count.
*
* Return: true if the resulting refcount is 0, false otherwise
*/
bool refcount_sub_and_test(unsigned int i, refcount_t *r)
{
unsigned int old, new, val = atomic_read(&r->refs);
unsigned int new, val = atomic_read(&r->refs);
for (;;) {
do {
if (unlikely(val == UINT_MAX))
return false;
@ -129,24 +185,24 @@ bool refcount_sub_and_test(unsigned int i, refcount_t *r)
return false;
}
old = atomic_cmpxchg_release(&r->refs, val, new);
if (old == val)
break;
val = old;
}
} while (!atomic_try_cmpxchg_release(&r->refs, &val, new));
return !new;
}
EXPORT_SYMBOL_GPL(refcount_sub_and_test);
/*
/**
* refcount_dec_and_test - decrement a refcount and test if it is 0
* @r: the refcount
*
* Similar to atomic_dec_and_test(), it will WARN on underflow and fail to
* decrement when saturated at UINT_MAX.
*
* Provides release memory ordering, such that prior loads and stores are done
* before, and provides a control dependency such that free() must come after.
* See the comment on top.
*
* Return: true if the resulting refcount is 0, false otherwise
*/
bool refcount_dec_and_test(refcount_t *r)
{
@ -154,21 +210,26 @@ bool refcount_dec_and_test(refcount_t *r)
}
EXPORT_SYMBOL_GPL(refcount_dec_and_test);
/*
/**
* refcount_dec - decrement a refcount
* @r: the refcount
*
* Similar to atomic_dec(), it will WARN on underflow and fail to decrement
* when saturated at UINT_MAX.
*
* Provides release memory ordering, such that prior loads and stores are done
* before.
*/
void refcount_dec(refcount_t *r)
{
WARN_ONCE(refcount_dec_and_test(r), "refcount_t: decrement hit 0; leaking memory.\n");
}
EXPORT_SYMBOL_GPL(refcount_dec);
/*
/**
* refcount_dec_if_one - decrement a refcount if it is 1
* @r: the refcount
*
* No atomic_t counterpart, it attempts a 1 -> 0 transition and returns the
* success thereof.
*
@ -178,24 +239,33 @@ EXPORT_SYMBOL_GPL(refcount_dec);
* It can be used like a try-delete operator; this explicit case is provided
* and not cmpxchg in generic, because that would allow implementing unsafe
* operations.
*
* Return: true if the resulting refcount is 0, false otherwise
*/
bool refcount_dec_if_one(refcount_t *r)
{
return atomic_cmpxchg_release(&r->refs, 1, 0) == 1;
int val = 1;
return atomic_try_cmpxchg_release(&r->refs, &val, 0);
}
EXPORT_SYMBOL_GPL(refcount_dec_if_one);
/*
/**
* refcount_dec_not_one - decrement a refcount if it is not 1
* @r: the refcount
*
* No atomic_t counterpart, it decrements unless the value is 1, in which case
* it will return false.
*
* Was often done like: atomic_add_unless(&var, -1, 1)
*
* Return: true if the decrement operation was successful, false otherwise
*/
bool refcount_dec_not_one(refcount_t *r)
{
unsigned int old, new, val = atomic_read(&r->refs);
unsigned int new, val = atomic_read(&r->refs);
for (;;) {
do {
if (unlikely(val == UINT_MAX))
return true;
@ -208,24 +278,27 @@ bool refcount_dec_not_one(refcount_t *r)
return true;
}
old = atomic_cmpxchg_release(&r->refs, val, new);
if (old == val)
break;
val = old;
}
} while (!atomic_try_cmpxchg_release(&r->refs, &val, new));
return true;
}
EXPORT_SYMBOL_GPL(refcount_dec_not_one);
/*
/**
* refcount_dec_and_mutex_lock - return holding mutex if able to decrement
* refcount to 0
* @r: the refcount
* @lock: the mutex to be locked
*
* Similar to atomic_dec_and_mutex_lock(), it will WARN on underflow and fail
* to decrement when saturated at UINT_MAX.
*
* Provides release memory ordering, such that prior loads and stores are done
* before, and provides a control dependency such that free() must come after.
* See the comment on top.
*
* Return: true and hold mutex if able to decrement refcount to 0, false
* otherwise
*/
bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock)
{
@ -242,13 +315,21 @@ bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock)
}
EXPORT_SYMBOL_GPL(refcount_dec_and_mutex_lock);
/*
/**
* refcount_dec_and_lock - return holding spinlock if able to decrement
* refcount to 0
* @r: the refcount
* @lock: the spinlock to be locked
*
* Similar to atomic_dec_and_lock(), it will WARN on underflow and fail to
* decrement when saturated at UINT_MAX.
*
* Provides release memory ordering, such that prior loads and stores are done
* before, and provides a control dependency such that free() must come after.
* See the comment on top.
*
* Return: true and hold spinlock if able to decrement refcount to 0, false
* otherwise
*/
bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock)
{

40
mm/percpu.c
View File

@ -1284,6 +1284,31 @@ void free_percpu(void __percpu *ptr)
}
EXPORT_SYMBOL_GPL(free_percpu);
bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
{
#ifdef CONFIG_SMP
const size_t static_size = __per_cpu_end - __per_cpu_start;
void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
unsigned int cpu;
for_each_possible_cpu(cpu) {
void *start = per_cpu_ptr(base, cpu);
void *va = (void *)addr;
if (va >= start && va < start + static_size) {
if (can_addr) {
*can_addr = (unsigned long) (va - start);
*can_addr += (unsigned long)
per_cpu_ptr(base, get_boot_cpu_id());
}
return true;
}
}
#endif
/* on UP, can't distinguish from other static vars, always false */
return false;
}
/**
* is_kernel_percpu_address - test whether address is from static percpu area
* @addr: address to test
@ -1297,20 +1322,7 @@ EXPORT_SYMBOL_GPL(free_percpu);
*/
bool is_kernel_percpu_address(unsigned long addr)
{
#ifdef CONFIG_SMP
const size_t static_size = __per_cpu_end - __per_cpu_start;
void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
unsigned int cpu;
for_each_possible_cpu(cpu) {
void *start = per_cpu_ptr(base, cpu);
if ((void *)addr >= start && (void *)addr < start + static_size)
return true;
}
#endif
/* on UP, can't distinguish from other static vars, always false */
return false;
return __is_kernel_percpu_address(addr, NULL);
}
/**