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locking: Remove spin_lock_flags() etc

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parisc, ia64 and powerpc32 are the only remaining architectures that
provide custom arch_{spin,read,write}_lock_flags() functions, which are
meant to re-enable interrupts while waiting for a spinlock.

However, none of these can actually run into this codepath, because
it is only called on architectures without CONFIG_GENERIC_LOCKBREAK,
or when CONFIG_DEBUG_LOCK_ALLOC is set without CONFIG_LOCKDEP, and none
of those combinations are possible on the three architectures.

Going back in the git history, it appears that arch/mn10300 may have
been able to run into this code path, but there is a good chance that
it never worked. On the architectures that still exist, it was
already impossible to hit back in 2008 after the introduction of
CONFIG_GENERIC_LOCKBREAK, and possibly earlier.

As this is all dead code, just remove it and the helper functions built
around it. For arch/ia64, the inline asm could be cleaned up, but
it seems safer to leave it untouched.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Helge Deller <deller@gmx.de>  # parisc
Link: https://lore.kernel.org/r/20211022120058.1031690-1-arnd@kernel.org
This commit is contained in:
Arnd Bergmann 2021-10-22 13:59:38 +02:00 committed by Peter Zijlstra
parent 5197fcd09a
commit f98a3dccfc
12 changed files with 9 additions and 125 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
arch/ia64/include/asm/spinlock.h
View File

@ -124,18 +124,13 @@ static __always_inline void arch_spin_unlock(arch_spinlock_t *lock)
__ticket_spin_unlock(lock);
}
static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock,
unsigned long flags)
{
arch_spin_lock(lock);
}
#define arch_spin_lock_flags arch_spin_lock_flags
#ifdef ASM_SUPPORTED
static __always_inline void
arch_read_lock_flags(arch_rwlock_t *lock, unsigned long flags)
arch_read_lock(arch_rwlock_t *lock)
{
unsigned long flags = 0;
__asm__ __volatile__ (
"tbit.nz p6, p0 = %1,%2\n"
"br.few 3f\n"
@ -157,13 +152,8 @@ arch_read_lock_flags(arch_rwlock_t *lock, unsigned long flags)
: "p6", "p7", "r2", "memory");
}
#define arch_read_lock_flags arch_read_lock_flags
#define arch_read_lock(lock) arch_read_lock_flags(lock, 0)
#else /* !ASM_SUPPORTED */
#define arch_read_lock_flags(rw, flags) arch_read_lock(rw)
#define arch_read_lock(rw) \
do { \
arch_rwlock_t *__read_lock_ptr = (rw); \
@ -186,8 +176,10 @@ do { \
#ifdef ASM_SUPPORTED
static __always_inline void
arch_write_lock_flags(arch_rwlock_t *lock, unsigned long flags)
arch_write_lock(arch_rwlock_t *lock)
{
unsigned long flags = 0;
__asm__ __volatile__ (
"tbit.nz p6, p0 = %1, %2\n"
"mov ar.ccv = r0\n"
@ -210,9 +202,6 @@ arch_write_lock_flags(arch_rwlock_t *lock, unsigned long flags)
: "ar.ccv", "p6", "p7", "r2", "r29", "memory");
}
#define arch_write_lock_flags arch_write_lock_flags
#define arch_write_lock(rw) arch_write_lock_flags(rw, 0)
#define arch_write_trylock(rw) \
({ \
register long result; \

3
arch/openrisc/include/asm/spinlock.h
View File

@ -19,9 +19,6 @@
#include <asm/qrwlock.h>
#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
#define arch_spin_relax(lock) cpu_relax()
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()

15
arch/parisc/include/asm/spinlock.h
View File

@ -23,21 +23,6 @@ static inline void arch_spin_lock(arch_spinlock_t *x)
continue;
}
static inline void arch_spin_lock_flags(arch_spinlock_t *x,
unsigned long flags)
{
volatile unsigned int *a;
a = __ldcw_align(x);
while (__ldcw(a) == 0)
while (*a == 0)
if (flags & PSW_SM_I) {
local_irq_enable();
local_irq_disable();
}
}
#define arch_spin_lock_flags arch_spin_lock_flags
static inline void arch_spin_unlock(arch_spinlock_t *x)
{
volatile unsigned int *a;

21
arch/powerpc/include/asm/simple_spinlock.h
View File

@ -123,27 +123,6 @@ static inline void arch_spin_lock(arch_spinlock_t *lock)
}
}
static inline
void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
{
unsigned long flags_dis;
while (1) {
if (likely(__arch_spin_trylock(lock) == 0))
break;
local_save_flags(flags_dis);
local_irq_restore(flags);
do {
HMT_low();
if (is_shared_processor())
splpar_spin_yield(lock);
} while (unlikely(lock->slock != 0));
HMT_medium();
local_irq_restore(flags_dis);
}
}
#define arch_spin_lock_flags arch_spin_lock_flags
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
__asm__ __volatile__("# arch_spin_unlock\n\t"

8
arch/s390/include/asm/spinlock.h
View File

@ -67,14 +67,6 @@ static inline void arch_spin_lock(arch_spinlock_t *lp)
arch_spin_lock_wait(lp);
}
static inline void arch_spin_lock_flags(arch_spinlock_t *lp,
unsigned long flags)
{
if (!arch_spin_trylock_once(lp))
arch_spin_lock_wait(lp);
}
#define arch_spin_lock_flags arch_spin_lock_flags
static inline int arch_spin_trylock(arch_spinlock_t *lp)
{
if (!arch_spin_trylock_once(lp))

17
include/linux/lockdep.h
View File

@ -481,23 +481,6 @@ do { \
#endif /* CONFIG_LOCK_STAT */
#ifdef CONFIG_LOCKDEP
/*
* On lockdep we dont want the hand-coded irq-enable of
* _raw_*_lock_flags() code, because lockdep assumes
* that interrupts are not re-enabled during lock-acquire:
*/
#define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
LOCK_CONTENDED((_lock), (try), (lock))
#else /* CONFIG_LOCKDEP */
#define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
lockfl((_lock), (flags))
#endif /* CONFIG_LOCKDEP */
#ifdef CONFIG_PROVE_LOCKING
extern void print_irqtrace_events(struct task_struct *curr);
#else

15
include/linux/rwlock.h
View File

@ -30,31 +30,16 @@ do { \
#ifdef CONFIG_DEBUG_SPINLOCK
extern void do_raw_read_lock(rwlock_t *lock) __acquires(lock);
#define do_raw_read_lock_flags(lock, flags) do_raw_read_lock(lock)
extern int do_raw_read_trylock(rwlock_t *lock);
extern void do_raw_read_unlock(rwlock_t *lock) __releases(lock);
extern void do_raw_write_lock(rwlock_t *lock) __acquires(lock);
#define do_raw_write_lock_flags(lock, flags) do_raw_write_lock(lock)
extern int do_raw_write_trylock(rwlock_t *lock);
extern void do_raw_write_unlock(rwlock_t *lock) __releases(lock);
#else
#ifndef arch_read_lock_flags
# define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
#endif
#ifndef arch_write_lock_flags
# define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
#endif
# define do_raw_read_lock(rwlock) do {__acquire(lock); arch_read_lock(&(rwlock)->raw_lock); } while (0)
# define do_raw_read_lock_flags(lock, flags) \
do {__acquire(lock); arch_read_lock_flags(&(lock)->raw_lock, *(flags)); } while (0)
# define do_raw_read_trylock(rwlock) arch_read_trylock(&(rwlock)->raw_lock)
# define do_raw_read_unlock(rwlock) do {arch_read_unlock(&(rwlock)->raw_lock); __release(lock); } while (0)
# define do_raw_write_lock(rwlock) do {__acquire(lock); arch_write_lock(&(rwlock)->raw_lock); } while (0)
# define do_raw_write_lock_flags(lock, flags) \
do {__acquire(lock); arch_write_lock_flags(&(lock)->raw_lock, *(flags)); } while (0)
# define do_raw_write_trylock(rwlock) arch_write_trylock(&(rwlock)->raw_lock)
# define do_raw_write_unlock(rwlock) do {arch_write_unlock(&(rwlock)->raw_lock); __release(lock); } while (0)
#endif

6
include/linux/rwlock_api_smp.h
View File

@ -157,8 +157,7 @@ static inline unsigned long __raw_read_lock_irqsave(rwlock_t *lock)
local_irq_save(flags);
preempt_disable();
rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
LOCK_CONTENDED_FLAGS(lock, do_raw_read_trylock, do_raw_read_lock,
do_raw_read_lock_flags, &flags);
LOCK_CONTENDED(lock, do_raw_read_trylock, do_raw_read_lock);
return flags;
}
@ -184,8 +183,7 @@ static inline unsigned long __raw_write_lock_irqsave(rwlock_t *lock)
local_irq_save(flags);
preempt_disable();
rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
LOCK_CONTENDED_FLAGS(lock, do_raw_write_trylock, do_raw_write_lock,
do_raw_write_lock_flags, &flags);
LOCK_CONTENDED(lock, do_raw_write_trylock, do_raw_write_lock);
return flags;
}

13
include/linux/spinlock.h
View File

@ -177,7 +177,6 @@ do { \
#ifdef CONFIG_DEBUG_SPINLOCK
extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
#define do_raw_spin_lock_flags(lock, flags) do_raw_spin_lock(lock)
extern int do_raw_spin_trylock(raw_spinlock_t *lock);
extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
#else
@ -188,18 +187,6 @@ static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
mmiowb_spin_lock();
}
#ifndef arch_spin_lock_flags
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
#endif
static inline void
do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock)
{
__acquire(lock);
arch_spin_lock_flags(&lock->raw_lock, *flags);
mmiowb_spin_lock();
}
static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
{
int ret = arch_spin_trylock(&(lock)->raw_lock);

9
include/linux/spinlock_api_smp.h
View File

@ -108,16 +108,7 @@ static inline unsigned long __raw_spin_lock_irqsave(raw_spinlock_t *lock)
local_irq_save(flags);
preempt_disable();
spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
/*
* On lockdep we dont want the hand-coded irq-enable of
* do_raw_spin_lock_flags() code, because lockdep assumes
* that interrupts are not re-enabled during lock-acquire:
*/
#ifdef CONFIG_LOCKDEP
LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
#else
do_raw_spin_lock_flags(lock, &flags);
#endif
return flags;
}

1
include/linux/spinlock_up.h
View File

@ -62,7 +62,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock)
#define arch_spin_is_locked(lock) ((void)(lock), 0)
/* for sched/core.c and kernel_lock.c: */
# define arch_spin_lock(lock) do { barrier(); (void)(lock); } while (0)
# define arch_spin_lock_flags(lock, flags) do { barrier(); (void)(lock); } while (0)
# define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0)
# define arch_spin_trylock(lock) ({ barrier(); (void)(lock); 1; })
#endif /* DEBUG_SPINLOCK */

3
kernel/locking/spinlock.c
View File

@ -378,8 +378,7 @@ unsigned long __lockfunc _raw_spin_lock_irqsave_nested(raw_spinlock_t *lock,
local_irq_save(flags);
preempt_disable();
spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
LOCK_CONTENDED_FLAGS(lock, do_raw_spin_trylock, do_raw_spin_lock,
do_raw_spin_lock_flags, &flags);
LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
return flags;
}
EXPORT_SYMBOL(_raw_spin_lock_irqsave_nested);