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

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

   - Adding transitivity uniformly to rcu_node structure ->lock
     acquisitions.  (This is implemented by the first two commits on top
     of v4.4-rc2 due to the pervasive nature of this change.)

   - Documentation updates, including RCU requirements.

   - Expedited grace-period changes.

   - Miscellaneous fixes.

   - Linked-list fixes, courtesy of KTSAN.

   - Torture-test updates.

   - Late-breaking fix to sysrq-generated crash.

  One thing I should note is that these pieces of documentation are
  fairly large files:

    .../RCU/Design/Requirements/Requirements.html      | 2897 ++++++++++++++++++++
    .../RCU/Design/Requirements/Requirements.htmlx     | 2741 ++++++++++++++++++

  and are written in HTML, not the usual .txt style.  I hope they are
  fine"

Paul McKenney explains the html docs:
 "For whatever it is worth, the reason for this unconventional choice
  was that attempts to do the diagrams in ASCII art failed miserably.

  And attempts to do ASCII art for the upcoming documentation of the
  data structures failed even more miserably"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (49 commits)
  sysrq: Fix warning in sysrq generated crash.
  list: Add lockless list traversal primitives
  rcu: Make rcu_gp_init() be bool rather than int
  rcu: Move wakeup out from under rnp->lock
  rcu: Fix comment for rcu_dereference_raw_notrace
  rcu: Don't redundantly disable irqs in rcu_irq_{enter,exit}()
  rcu: Make cpu_needs_another_gp() be bool
  rcu: Eliminate unused rcu_init_one() argument
  rcu: Remove TINY_RCU bloat from pointless boot parameters
  torture: Place console.log files correctly from the get-go
  torture: Abbreviate console error dump
  rcutorture: Print symbolic name for ->gp_state
  rcutorture: Print symbolic name for rcu_torture_writer_state
  rcutorture: Remove CONFIG_RCU_USER_QS from rcutorture selftest doc
  rcutorture: Default grace period to three minutes, allow override
  rcutorture:  Dump stack when GP kthread stalls
  rcutorture: Flag nonexistent RCU GP kthread
  rcutorture: Add batch number to script printout
  Documentation/memory-barriers.txt: Fix ACCESS_ONCE thinko
  documentation: Update RCU requirements based on expedited changes
  ...
This commit is contained in:
Linus Torvalds 2016-01-11 13:46:11 -08:00
commit 9061cbe62a
34 changed files with 7550 additions and 285 deletions
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2897
Documentation/RCU/Design/Requirements/Requirements.html Normal file
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2741
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108
Documentation/RCU/Design/htmlqqz.sh Executable file
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@ -0,0 +1,108 @@
#!/bin/sh
#
# Usage: sh htmlqqz.sh file
#
# Extracts and converts quick quizzes in a proto-HTML document file.htmlx.
# Commands, all of which must be on a line by themselves:
#
# "<p>@@QQ@@": Start of a quick quiz.
# "<p>@@QQA@@": Start of a quick-quiz answer.
# "<p>@@QQE@@": End of a quick-quiz answer, and thus of the quick quiz.
# "<p>@@QQAL@@": Place to put quick-quiz answer list.
#
# Places the result in file.html.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, you can access it online at
# http://www.gnu.org/licenses/gpl-2.0.html.
#
# Copyright (c) 2013 Paul E. McKenney, IBM Corporation.
fn=$1
if test ! -r $fn.htmlx
then
echo "Error: $fn.htmlx unreadable."
exit 1
fi
echo "<!-- DO NOT HAND EDIT. -->" > $fn.html
echo "<!-- Instead, edit $fn.htmlx and run 'sh htmlqqz.sh $fn' -->" >> $fn.html
awk < $fn.htmlx >> $fn.html '
state == "" && $1 != "<p>@@QQ@@" && $1 != "<p>@@QQAL@@" {
print $0;
if ($0 ~ /^<p>@@QQ/)
print "Bad Quick Quiz command: " NR " (expected <p>@@QQ@@ or <p>@@QQAL@@)." > "/dev/stderr"
next;
}
state == "" && $1 == "<p>@@QQ@@" {
qqn++;
qqlineno = NR;
haveqq = 1;
state = "qq";
print "<p><a name=\"Quick Quiz " qqn "\"><b>Quick Quiz " qqn "</b>:</a>"
next;
}
state == "qq" && $1 != "<p>@@QQA@@" {
qq[qqn] = qq[qqn] $0 "\n";
print $0
if ($0 ~ /^<p>@@QQ/)
print "Bad Quick Quiz command: " NR ". (expected <p>@@QQA@@)" > "/dev/stderr"
next;
}
state == "qq" && $1 == "<p>@@QQA@@" {
state = "qqa";
print "<br><a href=\"#qq" qqn "answer\">Answer</a>"
next;
}
state == "qqa" && $1 != "<p>@@QQE@@" {
qqa[qqn] = qqa[qqn] $0 "\n";
if ($0 ~ /^<p>@@QQ/)
print "Bad Quick Quiz command: " NR " (expected <p>@@QQE@@)." > "/dev/stderr"
next;
}
state == "qqa" && $1 == "<p>@@QQE@@" {
state = "";
next;
}
state == "" && $1 == "<p>@@QQAL@@" {
haveqq = "";
print "<h3><a name=\"Answers to Quick Quizzes\">"
print "Answers to Quick Quizzes</a></h3>"
print "";
for (i = 1; i <= qqn; i++) {
print "<a name=\"qq" i "answer\"></a>"
print "<p><b>Quick Quiz " i "</b>:"
print qq[i];
print "";
print "</p><p><b>Answer</b>:"
print qqa[i];
print "";
print "</p><p><a href=\"#Quick%20Quiz%20" i "\"><b>Back to Quick Quiz " i "</b>.</a>"
print "";
}
next;
}
END {
if (state != "")
print "Unterminated Quick Quiz: " qqlineno "." > "/dev/stderr"
else if (haveqq)
print "Missing \"<p>@@QQAL@@\", no Quick Quiz." > "/dev/stderr"
}'

25
Documentation/kernel-parameters.txt
View File

@ -3296,18 +3296,35 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
rcutorture.verbose= [KNL]
Enable additional printk() statements.
rcupdate.rcu_cpu_stall_suppress= [KNL]
Suppress RCU CPU stall warning messages.
rcupdate.rcu_cpu_stall_timeout= [KNL]
Set timeout for RCU CPU stall warning messages.
rcupdate.rcu_expedited= [KNL]
Use expedited grace-period primitives, for
example, synchronize_rcu_expedited() instead
of synchronize_rcu(). This reduces latency,
but can increase CPU utilization, degrade
real-time latency, and degrade energy efficiency.
No effect on CONFIG_TINY_RCU kernels.
rcupdate.rcu_cpu_stall_suppress= [KNL]
Suppress RCU CPU stall warning messages.
rcupdate.rcu_normal= [KNL]
Use only normal grace-period primitives,
for example, synchronize_rcu() instead of
synchronize_rcu_expedited(). This improves
real-time latency, CPU utilization, and
energy efficiency, but can expose users to
increased grace-period latency. This parameter
overrides rcupdate.rcu_expedited. No effect on
CONFIG_TINY_RCU kernels.
rcupdate.rcu_cpu_stall_timeout= [KNL]
Set timeout for RCU CPU stall warning messages.
rcupdate.rcu_normal_after_boot= [KNL]
Once boot has completed (that is, after
rcu_end_inkernel_boot() has been invoked), use
only normal grace-period primitives. No effect
on CONFIG_TINY_RCU kernels.
rcupdate.rcu_task_stall_timeout= [KNL]
Set timeout in jiffies for RCU task stall warning

8
Documentation/memory-barriers.txt
View File

@ -194,7 +194,7 @@ There are some minimal guarantees that may be expected of a CPU:
(*) On any given CPU, dependent memory accesses will be issued in order, with
respect to itself. This means that for:
WRITE_ONCE(Q, P); smp_read_barrier_depends(); D = READ_ONCE(*Q);
Q = READ_ONCE(P); smp_read_barrier_depends(); D = READ_ONCE(*Q);
the CPU will issue the following memory operations:
@ -202,9 +202,9 @@ There are some minimal guarantees that may be expected of a CPU:
and always in that order. On most systems, smp_read_barrier_depends()
does nothing, but it is required for DEC Alpha. The READ_ONCE()
and WRITE_ONCE() are required to prevent compiler mischief. Please
note that you should normally use something like rcu_dereference()
instead of open-coding smp_read_barrier_depends().
is required to prevent compiler mischief. Please note that you
should normally use something like rcu_dereference() instead of
open-coding smp_read_barrier_depends().
(*) Overlapping loads and stores within a particular CPU will appear to be
ordered within that CPU. This means that for:

6
drivers/tty/sysrq.c
View File

@ -133,6 +133,12 @@ static void sysrq_handle_crash(int key)
{
char *killer = NULL;
/* we need to release the RCU read lock here,
* otherwise we get an annoying
* 'BUG: sleeping function called from invalid context'
* complaint from the kernel before the panic.
*/
rcu_read_unlock();
panic_on_oops = 1; /* force panic */
wmb();
*killer = 1;

14
include/linux/list.h
View File

@ -24,7 +24,7 @@
static inline void INIT_LIST_HEAD(struct list_head *list)
{
list->next = list;
WRITE_ONCE(list->next, list);
list->prev = list;
}
@ -42,7 +42,7 @@ static inline void __list_add(struct list_head *new,
next->prev = new;
new->next = next;
new->prev = prev;
prev->next = new;
WRITE_ONCE(prev->next, new);
}
#else
extern void __list_add(struct list_head *new,
@ -186,7 +186,7 @@ static inline int list_is_last(const struct list_head *list,
*/
static inline int list_empty(const struct list_head *head)
{
return head->next == head;
return READ_ONCE(head->next) == head;
}
/**
@ -608,7 +608,7 @@ static inline int hlist_unhashed(const struct hlist_node *h)
static inline int hlist_empty(const struct hlist_head *h)
{
return !h->first;
return !READ_ONCE(h->first);
}
static inline void __hlist_del(struct hlist_node *n)
@ -642,7 +642,7 @@ static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
n->next = first;
if (first)
first->pprev = &n->next;
h->first = n;
WRITE_ONCE(h->first, n);
n->pprev = &h->first;
}
@ -653,14 +653,14 @@ static inline void hlist_add_before(struct hlist_node *n,
n->pprev = next->pprev;
n->next = next;
next->pprev = &n->next;
*(n->pprev) = n;
WRITE_ONCE(*(n->pprev), n);
}
static inline void hlist_add_behind(struct hlist_node *n,
struct hlist_node *prev)
{
n->next = prev->next;
prev->next = n;
WRITE_ONCE(prev->next, n);
n->pprev = &prev->next;
if (n->next)

2
include/linux/list_bl.h
View File

@ -70,7 +70,7 @@ static inline void hlist_bl_set_first(struct hlist_bl_head *h,
static inline int hlist_bl_empty(const struct hlist_bl_head *h)
{
return !((unsigned long)h->first & ~LIST_BL_LOCKMASK);
return !((unsigned long)READ_ONCE(h->first) & ~LIST_BL_LOCKMASK);
}
static inline void hlist_bl_add_head(struct hlist_bl_node *n,

2
include/linux/list_nulls.h
View File

@ -57,7 +57,7 @@ static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h)
static inline int hlist_nulls_empty(const struct hlist_nulls_head *h)
{
return is_a_nulls(h->first);
return is_a_nulls(READ_ONCE(h->first));
}
static inline void hlist_nulls_add_head(struct hlist_nulls_node *n,

105
include/linux/rculist.h
View File

@ -179,32 +179,31 @@ static inline void list_replace_rcu(struct list_head *old,
}
/**
* list_splice_init_rcu - splice an RCU-protected list into an existing list.
* __list_splice_init_rcu - join an RCU-protected list into an existing list.
* @list: the RCU-protected list to splice
* @head: the place in the list to splice the first list into
* @prev: points to the last element of the existing list
* @next: points to the first element of the existing list
* @sync: function to sync: synchronize_rcu(), synchronize_sched(), ...
*
* @head can be RCU-read traversed concurrently with this function.
* The list pointed to by @prev and @next can be RCU-read traversed
* concurrently with this function.
*
* Note that this function blocks.
*
* Important note: the caller must take whatever action is necessary to
* prevent any other updates to @head. In principle, it is possible
* to modify the list as soon as sync() begins execution.
* If this sort of thing becomes necessary, an alternative version
* based on call_rcu() could be created. But only if -really-
* needed -- there is no shortage of RCU API members.
* Important note: the caller must take whatever action is necessary to prevent
* any other updates to the existing list. In principle, it is possible to
* modify the list as soon as sync() begins execution. If this sort of thing
* becomes necessary, an alternative version based on call_rcu() could be
* created. But only if -really- needed -- there is no shortage of RCU API
* members.
*/
static inline void list_splice_init_rcu(struct list_head *list,
struct list_head *head,
void (*sync)(void))
static inline void __list_splice_init_rcu(struct list_head *list,
struct list_head *prev,
struct list_head *next,
void (*sync)(void))
{
struct list_head *first = list->next;
struct list_head *last = list->prev;
struct list_head *at = head->next;
if (list_empty(list))
return;
/*
* "first" and "last" tracking list, so initialize it. RCU readers
@ -231,10 +230,40 @@ static inline void list_splice_init_rcu(struct list_head *list,
* this function.
*/
last->next = at;
rcu_assign_pointer(list_next_rcu(head), first);
first->prev = head;
at->prev = last;
last->next = next;
rcu_assign_pointer(list_next_rcu(prev), first);
first->prev = prev;
next->prev = last;
}
/**
* list_splice_init_rcu - splice an RCU-protected list into an existing list,
* designed for stacks.
* @list: the RCU-protected list to splice
* @head: the place in the existing list to splice the first list into
* @sync: function to sync: synchronize_rcu(), synchronize_sched(), ...
*/
static inline void list_splice_init_rcu(struct list_head *list,
struct list_head *head,
void (*sync)(void))
{
if (!list_empty(list))
__list_splice_init_rcu(list, head, head->next, sync);
}
/**
* list_splice_tail_init_rcu - splice an RCU-protected list into an existing
* list, designed for queues.
* @list: the RCU-protected list to splice
* @head: the place in the existing list to splice the first list into
* @sync: function to sync: synchronize_rcu(), synchronize_sched(), ...
*/
static inline void list_splice_tail_init_rcu(struct list_head *list,
struct list_head *head,
void (*sync)(void))
{
if (!list_empty(list))
__list_splice_init_rcu(list, head->prev, head, sync);
}
/**
@ -304,6 +333,42 @@ static inline void list_splice_init_rcu(struct list_head *list,
&pos->member != (head); \
pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
/**
* list_entry_lockless - get the struct for this entry
* @ptr: the &struct list_head pointer.
* @type: the type of the struct this is embedded in.
* @member: the name of the list_head within the struct.
*
* This primitive may safely run concurrently with the _rcu list-mutation
* primitives such as list_add_rcu(), but requires some implicit RCU
* read-side guarding. One example is running within a special
* exception-time environment where preemption is disabled and where
* lockdep cannot be invoked (in which case updaters must use RCU-sched,
* as in synchronize_sched(), call_rcu_sched(), and friends). Another
* example is when items are added to the list, but never deleted.
*/
#define list_entry_lockless(ptr, type, member) \
container_of((typeof(ptr))lockless_dereference(ptr), type, member)
/**
* list_for_each_entry_lockless - iterate over rcu list of given type
* @pos: the type * to use as a loop cursor.
* @head: the head for your list.
* @member: the name of the list_struct within the struct.
*
* This primitive may safely run concurrently with the _rcu list-mutation
* primitives such as list_add_rcu(), but requires some implicit RCU
* read-side guarding. One example is running within a special
* exception-time environment where preemption is disabled and where
* lockdep cannot be invoked (in which case updaters must use RCU-sched,
* as in synchronize_sched(), call_rcu_sched(), and friends). Another
* example is when items are added to the list, but never deleted.
*/
#define list_for_each_entry_lockless(pos, head, member) \
for (pos = list_entry_lockless((head)->next, typeof(*pos), member); \
&pos->member != (head); \
pos = list_entry_lockless(pos->member.next, typeof(*pos), member))
/**
* list_for_each_entry_continue_rcu - continue iteration over list of given type
* @pos: the type * to use as a loop cursor.

21
include/linux/rcupdate.h
View File

@ -48,10 +48,17 @@
#include <asm/barrier.h>
#ifndef CONFIG_TINY_RCU
extern int rcu_expedited; /* for sysctl */
extern int rcu_normal; /* also for sysctl */
#endif /* #ifndef CONFIG_TINY_RCU */
#ifdef CONFIG_TINY_RCU
/* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */
static inline bool rcu_gp_is_normal(void) /* Internal RCU use. */
{
return true;
}
static inline bool rcu_gp_is_expedited(void) /* Internal RCU use. */
{
return false;
@ -65,6 +72,7 @@ static inline void rcu_unexpedite_gp(void)
{
}
#else /* #ifdef CONFIG_TINY_RCU */
bool rcu_gp_is_normal(void); /* Internal RCU use. */
bool rcu_gp_is_expedited(void); /* Internal RCU use. */
void rcu_expedite_gp(void);
void rcu_unexpedite_gp(void);
@ -321,7 +329,6 @@ static inline int rcu_preempt_depth(void)
/* Internal to kernel */
void rcu_init(void);
void rcu_end_inkernel_boot(void);
void rcu_sched_qs(void);
void rcu_bh_qs(void);
void rcu_check_callbacks(int user);
@ -329,6 +336,12 @@ struct notifier_block;
int rcu_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu);
#ifndef CONFIG_TINY_RCU
void rcu_end_inkernel_boot(void);
#else /* #ifndef CONFIG_TINY_RCU */
static inline void rcu_end_inkernel_boot(void) { }
#endif /* #ifndef CONFIG_TINY_RCU */
#ifdef CONFIG_RCU_STALL_COMMON
void rcu_sysrq_start(void);
void rcu_sysrq_end(void);
@ -379,9 +392,9 @@ static inline void rcu_init_nohz(void)
*/
#define RCU_NONIDLE(a) \
do { \
rcu_irq_enter(); \
rcu_irq_enter_irqson(); \
do { a; } while (0); \
rcu_irq_exit(); \
rcu_irq_exit_irqson(); \
} while (0)
/*
@ -741,7 +754,7 @@ static inline void rcu_preempt_sleep_check(void)
* The tracing infrastructure traces RCU (we want that), but unfortunately
* some of the RCU checks causes tracing to lock up the system.
*
* The tracing version of rcu_dereference_raw() must not call
* The no-tracing version of rcu_dereference_raw() must not call
* rcu_read_lock_held().
*/
#define rcu_dereference_raw_notrace(p) __rcu_dereference_check((p), 1, __rcu)

8
include/linux/rcutiny.h
View File

@ -181,6 +181,14 @@ static inline void rcu_irq_enter(void)
{
}
static inline void rcu_irq_exit_irqson(void)
{
}
static inline void rcu_irq_enter_irqson(void)
{
}
static inline void rcu_irq_exit(void)
{
}

4
include/linux/rcutree.h
View File

@ -37,7 +37,7 @@ void rcu_cpu_stall_reset(void);
/*
* Note a virtualization-based context switch. This is simply a
* wrapper around rcu_note_context_switch(), which allows TINY_RCU
* to save a few bytes.
* to save a few bytes. The caller must have disabled interrupts.
*/
static inline void rcu_virt_note_context_switch(int cpu)
{
@ -97,6 +97,8 @@ void rcu_idle_enter(void);
void rcu_idle_exit(void);
void rcu_irq_enter(void);
void rcu_irq_exit(void);
void rcu_irq_enter_irqson(void);
void rcu_irq_exit_irqson(void);
void exit_rcu(void);

4
include/linux/tracepoint.h
View File

@ -171,8 +171,8 @@ extern void syscall_unregfunc(void);
TP_PROTO(data_proto), \
TP_ARGS(data_args), \
TP_CONDITION(cond), \
rcu_irq_enter(), \
rcu_irq_exit()); \
rcu_irq_enter_irqson(), \
rcu_irq_exit_irqson()); \
}
#else
#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)

2
init/main.c
View File

@ -943,6 +943,8 @@ static int __ref kernel_init(void *unused)
flush_delayed_fput();
rcu_end_inkernel_boot();
if (ramdisk_execute_command) {
ret = run_init_process(ramdisk_execute_command);
if (!ret)

26
kernel/ksysfs.c
View File

@ -20,7 +20,7 @@
#include <linux/capability.h>
#include <linux/compiler.h>
#include <linux/rcupdate.h> /* rcu_expedited */
#include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */
#define KERNEL_ATTR_RO(_name) \
static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
@ -144,11 +144,12 @@ static ssize_t fscaps_show(struct kobject *kobj,
}
KERNEL_ATTR_RO(fscaps);
#ifndef CONFIG_TINY_RCU
int rcu_expedited;
static ssize_t rcu_expedited_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", rcu_expedited);
return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
}
static ssize_t rcu_expedited_store(struct kobject *kobj,
struct kobj_attribute *attr,
@ -161,6 +162,24 @@ static ssize_t rcu_expedited_store(struct kobject *kobj,
}
KERNEL_ATTR_RW(rcu_expedited);
int rcu_normal;
static ssize_t rcu_normal_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
}
static ssize_t rcu_normal_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
if (kstrtoint(buf, 0, &rcu_normal))
return -EINVAL;
return count;
}
KERNEL_ATTR_RW(rcu_normal);
#endif /* #ifndef CONFIG_TINY_RCU */
/*
* Make /sys/kernel/notes give the raw contents of our kernel .notes section.
*/
@ -202,7 +221,10 @@ static struct attribute * kernel_attrs[] = {
&kexec_crash_size_attr.attr,
&vmcoreinfo_attr.attr,
#endif
#ifndef CONFIG_TINY_RCU
&rcu_expedited_attr.attr,
&rcu_normal_attr.attr,
#endif
NULL
};

24
kernel/rcu/rcutorture.c
View File

@ -162,6 +162,27 @@ static int rcu_torture_writer_state;
#define RTWS_SYNC 7
#define RTWS_STUTTER 8
#define RTWS_STOPPING 9
static const char * const rcu_torture_writer_state_names[] = {
"RTWS_FIXED_DELAY",
"RTWS_DELAY",
"RTWS_REPLACE",
"RTWS_DEF_FREE",
"RTWS_EXP_SYNC",
"RTWS_COND_GET",
"RTWS_COND_SYNC",
"RTWS_SYNC",
"RTWS_STUTTER",
"RTWS_STOPPING",
};
static const char *rcu_torture_writer_state_getname(void)
{
unsigned int i = READ_ONCE(rcu_torture_writer_state);
if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
return "???";
return rcu_torture_writer_state_names[i];
}
#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
#define RCUTORTURE_RUNNABLE_INIT 1
@ -1307,7 +1328,8 @@ rcu_torture_stats_print(void)
rcutorture_get_gp_data(cur_ops->ttype,
&flags, &gpnum, &completed);
pr_alert("??? Writer stall state %d g%lu c%lu f%#x\n",
pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x\n",
rcu_torture_writer_state_getname(),
rcu_torture_writer_state,
gpnum, completed, flags);
show_rcu_gp_kthreads();

2
kernel/rcu/srcu.c
View File

@ -489,7 +489,7 @@ static void __synchronize_srcu(struct srcu_struct *sp, int trycount)
*/
void synchronize_srcu(struct srcu_struct *sp)
{
__synchronize_srcu(sp, rcu_gp_is_expedited()
__synchronize_srcu(sp, (rcu_gp_is_expedited() && !rcu_gp_is_normal())
? SYNCHRONIZE_SRCU_EXP_TRYCOUNT
: SYNCHRONIZE_SRCU_TRYCOUNT);
}

315
kernel/rcu/tree.c
View File

@ -68,10 +68,6 @@ MODULE_ALIAS("rcutree");
/* Data structures. */
static struct lock_class_key rcu_node_class[RCU_NUM_LVLS];
static struct lock_class_key rcu_fqs_class[RCU_NUM_LVLS];
static struct lock_class_key rcu_exp_class[RCU_NUM_LVLS];
/*
* In order to export the rcu_state name to the tracing tools, it
* needs to be added in the __tracepoint_string section.
@ -246,24 +242,17 @@ static int rcu_gp_in_progress(struct rcu_state *rsp)
*/
void rcu_sched_qs(void)
{
unsigned long flags;
if (__this_cpu_read(rcu_sched_data.cpu_no_qs.s)) {
trace_rcu_grace_period(TPS("rcu_sched"),
__this_cpu_read(rcu_sched_data.gpnum),
TPS("cpuqs"));
__this_cpu_write(rcu_sched_data.cpu_no_qs.b.norm, false);
if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp))
return;
local_irq_save(flags);
if (__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp)) {
__this_cpu_write(rcu_sched_data.cpu_no_qs.b.exp, false);
rcu_report_exp_rdp(&rcu_sched_state,
this_cpu_ptr(&rcu_sched_data),
true);
}
local_irq_restore(flags);
}
if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.s))
return;
trace_rcu_grace_period(TPS("rcu_sched"),
__this_cpu_read(rcu_sched_data.gpnum),
TPS("cpuqs"));
__this_cpu_write(rcu_sched_data.cpu_no_qs.b.norm, false);
if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp))
return;
__this_cpu_write(rcu_sched_data.cpu_no_qs.b.exp, false);
rcu_report_exp_rdp(&rcu_sched_state,
this_cpu_ptr(&rcu_sched_data), true);
}
void rcu_bh_qs(void)
@ -300,17 +289,16 @@ EXPORT_PER_CPU_SYMBOL_GPL(rcu_qs_ctr);
* We inform the RCU core by emulating a zero-duration dyntick-idle
* period, which we in turn do by incrementing the ->dynticks counter
* by two.
*
* The caller must have disabled interrupts.
*/
static void rcu_momentary_dyntick_idle(void)
{
unsigned long flags;
struct rcu_data *rdp;
struct rcu_dynticks *rdtp;
int resched_mask;
struct rcu_state *rsp;
local_irq_save(flags);
/*
* Yes, we can lose flag-setting operations. This is OK, because
* the flag will be set again after some delay.
@ -340,13 +328,12 @@ static void rcu_momentary_dyntick_idle(void)
smp_mb__after_atomic(); /* Later stuff after QS. */
break;
}
local_irq_restore(flags);
}
/*
* Note a context switch. This is a quiescent state for RCU-sched,
* and requires special handling for preemptible RCU.
* The caller must have disabled preemption.
* The caller must have disabled interrupts.
*/
void rcu_note_context_switch(void)
{
@ -376,9 +363,14 @@ EXPORT_SYMBOL_GPL(rcu_note_context_switch);
*/
void rcu_all_qs(void)
{
unsigned long flags;
barrier(); /* Avoid RCU read-side critical sections leaking down. */
if (unlikely(raw_cpu_read(rcu_sched_qs_mask)))
if (unlikely(raw_cpu_read(rcu_sched_qs_mask))) {
local_irq_save(flags);
rcu_momentary_dyntick_idle();
local_irq_restore(flags);
}
this_cpu_inc(rcu_qs_ctr);
barrier(); /* Avoid RCU read-side critical sections leaking up. */
}
@ -605,25 +597,25 @@ static int rcu_future_needs_gp(struct rcu_state *rsp)
* The caller must have disabled interrupts to prevent races with
* normal callback registry.
*/
static int
static bool
cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp)
{
int i;
if (rcu_gp_in_progress(rsp))
return 0; /* No, a grace period is already in progress. */
return false; /* No, a grace period is already in progress. */
if (rcu_future_needs_gp(rsp))
return 1; /* Yes, a no-CBs CPU needs one. */
return true; /* Yes, a no-CBs CPU needs one. */
if (!rdp->nxttail[RCU_NEXT_TAIL])
return 0; /* No, this is a no-CBs (or offline) CPU. */
return false; /* No, this is a no-CBs (or offline) CPU. */
if (*rdp->nxttail[RCU_NEXT_READY_TAIL])
return 1; /* Yes, this CPU has newly registered callbacks. */
return true; /* Yes, CPU has newly registered callbacks. */
for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++)
if (rdp->nxttail[i - 1] != rdp->nxttail[i] &&
ULONG_CMP_LT(READ_ONCE(rsp->completed),
rdp->nxtcompleted[i]))
return 1; /* Yes, CBs for future grace period. */
return 0; /* No grace period needed. */
return true; /* Yes, CBs for future grace period. */
return false; /* No grace period needed. */
}
/*
@ -740,7 +732,7 @@ void rcu_user_enter(void)
*
* Exit from an interrupt handler, which might possibly result in entering
* idle mode, in other words, leaving the mode in which read-side critical
* sections can occur.
* sections can occur. The caller must have disabled interrupts.
*
* This code assumes that the idle loop never does anything that might
* result in unbalanced calls to irq_enter() and irq_exit(). If your
@ -753,11 +745,10 @@ void rcu_user_enter(void)
*/
void rcu_irq_exit(void)
{
unsigned long flags;
long long oldval;
struct rcu_dynticks *rdtp;
local_irq_save(flags);
RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_exit() invoked with irqs enabled!!!");
rdtp = this_cpu_ptr(&rcu_dynticks);
oldval = rdtp->dynticks_nesting;
rdtp->dynticks_nesting--;
@ -768,6 +759,17 @@ void rcu_irq_exit(void)
else
rcu_eqs_enter_common(oldval, true);
rcu_sysidle_enter(1);
}
/*
* Wrapper for rcu_irq_exit() where interrupts are enabled.
*/
void rcu_irq_exit_irqson(void)
{
unsigned long flags;
local_irq_save(flags);
rcu_irq_exit();
local_irq_restore(flags);
}
@ -865,7 +867,7 @@ void rcu_user_exit(void)
*
* Enter an interrupt handler, which might possibly result in exiting
* idle mode, in other words, entering the mode in which read-side critical
* sections can occur.
* sections can occur. The caller must have disabled interrupts.
*
* Note that the Linux kernel is fully capable of entering an interrupt
* handler that it never exits, for example when doing upcalls to
@ -881,11 +883,10 @@ void rcu_user_exit(void)
*/
void rcu_irq_enter(void)
{
unsigned long flags;
struct rcu_dynticks *rdtp;
long long oldval;
local_irq_save(flags);
RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_enter() invoked with irqs enabled!!!");
rdtp = this_cpu_ptr(&rcu_dynticks);
oldval = rdtp->dynticks_nesting;
rdtp->dynticks_nesting++;
@ -896,6 +897,17 @@ void rcu_irq_enter(void)
else
rcu_eqs_exit_common(oldval, true);
rcu_sysidle_exit(1);
}
/*
* Wrapper for rcu_irq_enter() where interrupts are enabled.
*/
void rcu_irq_enter_irqson(void)
{
unsigned long flags;
local_irq_save(flags);
rcu_irq_enter();
local_irq_restore(flags);
}
@ -1186,6 +1198,16 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
rsp->n_force_qs_gpstart = READ_ONCE(rsp->n_force_qs);
}
/*
* Convert a ->gp_state value to a character string.
*/
static const char *gp_state_getname(short gs)
{
if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
return "???";
return gp_state_names[gs];
}
/*
* Complain about starvation of grace-period kthread.
*/
@ -1196,12 +1218,16 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
j = jiffies;
gpa = READ_ONCE(rsp->gp_activity);
if (j - gpa > 2 * HZ)
pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x s%d ->state=%#lx\n",
if (j - gpa > 2 * HZ) {
pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x %s(%d) ->state=%#lx\n",
rsp->name, j - gpa,
rsp->gpnum, rsp->completed,
rsp->gp_flags, rsp->gp_state,
rsp->gp_kthread ? rsp->gp_kthread->state : 0);
rsp->gp_flags,
gp_state_getname(rsp->gp_state), rsp->gp_state,
rsp->gp_kthread ? rsp->gp_kthread->state : ~0);
if (rsp->gp_kthread)
sched_show_task(rsp->gp_kthread);
}
}
/*
@ -1214,7 +1240,7 @@ static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
struct rcu_node *rnp;
rcu_for_each_leaf_node(rsp, rnp) {
raw_spin_lock_irqsave(&rnp->lock, flags);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (rnp->qsmask != 0) {
for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
if (rnp->qsmask & (1UL << cpu))
@ -1237,7 +1263,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
/* Only let one CPU complain about others per time interval. */
raw_spin_lock_irqsave(&rnp->lock, flags);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
delta = jiffies - READ_ONCE(rsp->jiffies_stall);
if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
@ -1256,7 +1282,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
rsp->name);
print_cpu_stall_info_begin();
rcu_for_each_leaf_node(rsp, rnp) {
raw_spin_lock_irqsave(&rnp->lock, flags);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
ndetected += rcu_print_task_stall(rnp);
if (rnp->qsmask != 0) {
for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
@ -1327,7 +1353,7 @@ static void print_cpu_stall(struct rcu_state *rsp)
rcu_dump_cpu_stacks(rsp);
raw_spin_lock_irqsave(&rnp->lock, flags);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (ULONG_CMP_GE(jiffies, READ_ONCE(rsp->jiffies_stall)))
WRITE_ONCE(rsp->jiffies_stall,
jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
@ -1534,10 +1560,8 @@ rcu_start_future_gp(struct rcu_node *rnp, struct rcu_data *rdp,
* hold it, acquire the root rcu_node structure's lock in order to
* start one (if needed).
*/
if (rnp != rnp_root) {
raw_spin_lock(&rnp_root->lock);
smp_mb__after_unlock_lock();
}
if (rnp != rnp_root)
raw_spin_lock_rcu_node(rnp_root);
/*
* Get a new grace-period number. If there really is no grace
@ -1786,11 +1810,10 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp)
if ((rdp->gpnum == READ_ONCE(rnp->gpnum) &&
rdp->completed == READ_ONCE(rnp->completed) &&
!unlikely(READ_ONCE(rdp->gpwrap))) || /* w/out lock. */
!raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */
!raw_spin_trylock_rcu_node(rnp)) { /* irqs already off, so later. */
local_irq_restore(flags);
return;
}
smp_mb__after_unlock_lock();
needwake = __note_gp_changes(rsp, rnp, rdp);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
if (needwake)
@ -1805,21 +1828,20 @@ static void rcu_gp_slow(struct rcu_state *rsp, int delay)
}
/*
* Initialize a new grace period. Return 0 if no grace period required.
* Initialize a new grace period. Return false if no grace period required.
*/
static int rcu_gp_init(struct rcu_state *rsp)
static bool rcu_gp_init(struct rcu_state *rsp)
{
unsigned long oldmask;
struct rcu_data *rdp;
struct rcu_node *rnp = rcu_get_root(rsp);
WRITE_ONCE(rsp->gp_activity, jiffies);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
raw_spin_lock_irq_rcu_node(rnp);
if (!READ_ONCE(rsp->gp_flags)) {
/* Spurious wakeup, tell caller to go back to sleep. */
raw_spin_unlock_irq(&rnp->lock);
return 0;
return false;
}
WRITE_ONCE(rsp->gp_flags, 0); /* Clear all flags: New grace period. */
@ -1829,7 +1851,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
* Not supposed to be able to happen.
*/
raw_spin_unlock_irq(&rnp->lock);
return 0;
return false;
}
/* Advance to a new grace period and initialize state. */
@ -1847,8 +1869,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
*/
rcu_for_each_leaf_node(rsp, rnp) {
rcu_gp_slow(rsp, gp_preinit_delay);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
raw_spin_lock_irq_rcu_node(rnp);
if (rnp->qsmaskinit == rnp->qsmaskinitnext &&
!rnp->wait_blkd_tasks) {
/* Nothing to do on this leaf rcu_node structure. */
@ -1904,8 +1925,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
*/
rcu_for_each_node_breadth_first(rsp, rnp) {
rcu_gp_slow(rsp, gp_init_delay);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
raw_spin_lock_irq_rcu_node(rnp);
rdp = this_cpu_ptr(rsp->rda);
rcu_preempt_check_blocked_tasks(rnp);
rnp->qsmask = rnp->qsmaskinit;
@ -1923,7 +1943,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
WRITE_ONCE(rsp->gp_activity, jiffies);
}
return 1;
return true;
}
/*
@ -1973,8 +1993,7 @@ static void rcu_gp_fqs(struct rcu_state *rsp, bool first_time)
}
/* Clear flag to prevent immediate re-entry. */
if (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
raw_spin_lock_irq_rcu_node(rnp);
WRITE_ONCE(rsp->gp_flags,
READ_ONCE(rsp->gp_flags) & ~RCU_GP_FLAG_FQS);
raw_spin_unlock_irq(&rnp->lock);
@ -1993,8 +2012,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
struct rcu_node *rnp = rcu_get_root(rsp);
WRITE_ONCE(rsp->gp_activity, jiffies);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
raw_spin_lock_irq_rcu_node(rnp);
gp_duration = jiffies - rsp->gp_start;
if (gp_duration > rsp->gp_max)
rsp->gp_max = gp_duration;
@ -2019,8 +2037,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
* grace period is recorded in any of the rcu_node structures.
*/
rcu_for_each_node_breadth_first(rsp, rnp) {
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
raw_spin_lock_irq_rcu_node(rnp);
WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp));
WARN_ON_ONCE(rnp->qsmask);
WRITE_ONCE(rnp->completed, rsp->gpnum);
@ -2035,8 +2052,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
rcu_gp_slow(rsp, gp_cleanup_delay);
}
rnp = rcu_get_root(rsp);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock(); /* Order GP before ->completed update. */
raw_spin_lock_irq_rcu_node(rnp); /* Order GP before ->completed update. */
rcu_nocb_gp_set(rnp, nocb);
/* Declare grace period done. */
@ -2284,8 +2300,7 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
raw_spin_unlock_irqrestore(&rnp->lock, flags);
rnp_c = rnp;
rnp = rnp->parent;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
oldmask = rnp_c->qsmask;
}
@ -2332,8 +2347,7 @@ static void rcu_report_unblock_qs_rnp(struct rcu_state *rsp,
gps = rnp->gpnum;
mask = rnp->grpmask;
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
raw_spin_lock(&rnp_p->lock); /* irqs already disabled. */
smp_mb__after_unlock_lock();
raw_spin_lock_rcu_node(rnp_p); /* irqs already disabled. */
rcu_report_qs_rnp(mask, rsp, rnp_p, gps, flags);
}
@ -2355,8 +2369,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp)
struct rcu_node *rnp;
rnp = rdp->mynode;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if ((rdp->cpu_no_qs.b.norm &&
rdp->rcu_qs_ctr_snap == __this_cpu_read(rcu_qs_ctr)) ||
rdp->gpnum != rnp->gpnum || rnp->completed == rnp->gpnum ||
@ -2582,8 +2595,7 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
rnp = rnp->parent;
if (!rnp)
break;
raw_spin_lock(&rnp->lock); /* irqs already disabled. */
smp_mb__after_unlock_lock(); /* GP memory ordering. */
raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
rnp->qsmaskinit &= ~mask;
rnp->qsmask &= ~mask;
if (rnp->qsmaskinit) {
@ -2611,8 +2623,7 @@ static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
/* Remove outgoing CPU from mask in the leaf rcu_node structure. */
mask = rdp->grpmask;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock(); /* Enforce GP memory-order guarantee. */
raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */
rnp->qsmaskinitnext &= ~mask;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
@ -2809,8 +2820,7 @@ static void force_qs_rnp(struct rcu_state *rsp,
rcu_for_each_leaf_node(rsp, rnp) {
cond_resched_rcu_qs();
mask = 0;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (rnp->qsmask == 0) {
if (rcu_state_p == &rcu_sched_state ||
rsp != rcu_state_p ||
@ -2881,8 +2891,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
/* rnp_old == rcu_get_root(rsp), rnp == NULL. */
/* Reached the root of the rcu_node tree, acquire lock. */
raw_spin_lock_irqsave(&rnp_old->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp_old, flags);
raw_spin_unlock(&rnp_old->fqslock);
if (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
rsp->n_force_qs_lh++;
@ -2914,7 +2923,7 @@ __rcu_process_callbacks(struct rcu_state *rsp)
/* Does this CPU require a not-yet-started grace period? */
local_irq_save(flags);
if (cpu_needs_another_gp(rsp, rdp)) {
raw_spin_lock(&rcu_get_root(rsp)->lock); /* irqs disabled. */
raw_spin_lock_rcu_node(rcu_get_root(rsp)); /* irqs disabled. */
needwake = rcu_start_gp(rsp);
raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags);
if (needwake)
@ -3005,8 +3014,7 @@ static void __call_rcu_core(struct rcu_state *rsp, struct rcu_data *rdp,
if (!rcu_gp_in_progress(rsp)) {
struct rcu_node *rnp_root = rcu_get_root(rsp);
raw_spin_lock(&rnp_root->lock);
smp_mb__after_unlock_lock();
raw_spin_lock_rcu_node(rnp_root);
needwake = rcu_start_gp(rsp);
raw_spin_unlock(&rnp_root->lock);
if (needwake)
@ -3365,7 +3373,6 @@ static unsigned long rcu_seq_snap(unsigned long *sp)
{
unsigned long s;
smp_mb(); /* Caller's modifications seen first by other CPUs. */
s = (READ_ONCE(*sp) + 3) & ~0x1;
smp_mb(); /* Above access must not bleed into critical section. */
return s;
@ -3392,6 +3399,7 @@ static void rcu_exp_gp_seq_end(struct rcu_state *rsp)
}
static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
{
smp_mb(); /* Caller's modifications seen first by other CPUs. */
return rcu_seq_snap(&rsp->expedited_sequence);
}
static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s)
@ -3426,8 +3434,7 @@ static void sync_exp_reset_tree_hotplug(struct rcu_state *rsp)
* CPUs for the current rcu_node structure up the rcu_node tree.
*/
rcu_for_each_leaf_node(rsp, rnp) {
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (rnp->expmaskinit == rnp->expmaskinitnext) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
continue; /* No new CPUs, nothing to do. */
@ -3447,8 +3454,7 @@ static void sync_exp_reset_tree_hotplug(struct rcu_state *rsp)
rnp_up = rnp->parent;
done = false;
while (rnp_up) {
raw_spin_lock_irqsave(&rnp_up->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp_up, flags);
if (rnp_up->expmaskinit)
done = true;
rnp_up->expmaskinit |= mask;
@ -3472,8 +3478,7 @@ static void __maybe_unused sync_exp_reset_tree(struct rcu_state *rsp)
sync_exp_reset_tree_hotplug(rsp);
rcu_for_each_node_breadth_first(rsp, rnp) {
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
WARN_ON_ONCE(rnp->expmask);
rnp->expmask = rnp->expmaskinit;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
@ -3531,8 +3536,7 @@ static void __rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
mask = rnp->grpmask;
raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
rnp = rnp->parent;
raw_spin_lock(&rnp->lock); /* irqs already disabled */
smp_mb__after_unlock_lock();
raw_spin_lock_rcu_node(rnp); /* irqs already disabled */
WARN_ON_ONCE(!(rnp->expmask & mask));
rnp->expmask &= ~mask;
}
@ -3549,8 +3553,7 @@ static void __maybe_unused rcu_report_exp_rnp(struct rcu_state *rsp,
{
unsigned long flags;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
__rcu_report_exp_rnp(rsp, rnp, wake, flags);
}
@ -3564,8 +3567,7 @@ static void rcu_report_exp_cpu_mult(struct rcu_state *rsp, struct rcu_node *rnp,
{
unsigned long flags;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (!(rnp->expmask & mask)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
@ -3609,7 +3611,7 @@ static bool sync_exp_work_done(struct rcu_state *rsp, struct rcu_node *rnp,
*/
static struct rcu_node *exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
{
struct rcu_data *rdp;
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id());
struct rcu_node *rnp0;
struct rcu_node *rnp1 = NULL;
@ -3623,7 +3625,7 @@ static struct rcu_node *exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
if (!mutex_is_locked(&rnp0->exp_funnel_mutex)) {
if (mutex_trylock(&rnp0->exp_funnel_mutex)) {
if (sync_exp_work_done(rsp, rnp0, NULL,
&rsp->expedited_workdone0, s))
&rdp->expedited_workdone0, s))
return NULL;
return rnp0;
}
@ -3637,14 +3639,13 @@ static struct rcu_node *exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
* can be inexact, as it is just promoting locality and is not
* strictly needed for correctness.
*/
rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id());
if (sync_exp_work_done(rsp, NULL, NULL, &rsp->expedited_workdone1, s))
if (sync_exp_work_done(rsp, NULL, NULL, &rdp->expedited_workdone1, s))
return NULL;
mutex_lock(&rdp->exp_funnel_mutex);
rnp0 = rdp->mynode;
for (; rnp0 != NULL; rnp0 = rnp0->parent) {
if (sync_exp_work_done(rsp, rnp1, rdp,
&rsp->expedited_workdone2, s))
&rdp->expedited_workdone2, s))
return NULL;
mutex_lock(&rnp0->exp_funnel_mutex);
if (rnp1)
@ -3654,7 +3655,7 @@ static struct rcu_node *exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
rnp1 = rnp0;
}
if (sync_exp_work_done(rsp, rnp1, rdp,
&rsp->expedited_workdone3, s))
&rdp->expedited_workdone3, s))
return NULL;
return rnp1;
}
@ -3708,8 +3709,7 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
sync_exp_reset_tree(rsp);
rcu_for_each_leaf_node(rsp, rnp) {
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
/* Each pass checks a CPU for identity, offline, and idle. */
mask_ofl_test = 0;
@ -3741,24 +3741,22 @@ retry_ipi:
ret = smp_call_function_single(cpu, func, rsp, 0);
if (!ret) {
mask_ofl_ipi &= ~mask;
} else {
/* Failed, raced with offline. */
raw_spin_lock_irqsave(&rnp->lock, flags);
if (cpu_online(cpu) &&
(rnp->expmask & mask)) {
raw_spin_unlock_irqrestore(&rnp->lock,
flags);
schedule_timeout_uninterruptible(1);
if (cpu_online(cpu) &&
(rnp->expmask & mask))
goto retry_ipi;
raw_spin_lock_irqsave(&rnp->lock,
flags);
}
if (!(rnp->expmask & mask))
mask_ofl_ipi &= ~mask;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
continue;
}
/* Failed, raced with offline. */
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (cpu_online(cpu) &&
(rnp->expmask & mask)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
schedule_timeout_uninterruptible(1);
if (cpu_online(cpu) &&
(rnp->expmask & mask))
goto retry_ipi;
raw_spin_lock_irqsave_rcu_node(rnp, flags);
}
if (!(rnp->expmask & mask))
mask_ofl_ipi &= ~mask;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
/* Report quiescent states for those that went offline. */
mask_ofl_test |= mask_ofl_ipi;
@ -3773,6 +3771,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
unsigned long jiffies_stall;
unsigned long jiffies_start;
unsigned long mask;
int ndetected;
struct rcu_node *rnp;
struct rcu_node *rnp_root = rcu_get_root(rsp);
int ret;
@ -3785,7 +3784,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
rsp->expedited_wq,
sync_rcu_preempt_exp_done(rnp_root),
jiffies_stall);
if (ret > 0)
if (ret > 0 || sync_rcu_preempt_exp_done(rnp_root))
return;
if (ret < 0) {
/* Hit a signal, disable CPU stall warnings. */
@ -3795,14 +3794,16 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
}
pr_err("INFO: %s detected expedited stalls on CPUs/tasks: {",
rsp->name);
ndetected = 0;
rcu_for_each_leaf_node(rsp, rnp) {
(void)rcu_print_task_exp_stall(rnp);
ndetected = rcu_print_task_exp_stall(rnp);
mask = 1;
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
struct rcu_data *rdp;
if (!(rnp->expmask & mask))
continue;
ndetected++;
rdp = per_cpu_ptr(rsp->rda, cpu);
pr_cont(" %d-%c%c%c", cpu,
"O."[cpu_online(cpu)],
@ -3811,8 +3812,23 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
}
mask <<= 1;
}
pr_cont(" } %lu jiffies s: %lu\n",
jiffies - jiffies_start, rsp->expedited_sequence);
pr_cont(" } %lu jiffies s: %lu root: %#lx/%c\n",
jiffies - jiffies_start, rsp->expedited_sequence,
rnp_root->expmask, ".T"[!!rnp_root->exp_tasks]);
if (!ndetected) {
pr_err("blocking rcu_node structures:");
rcu_for_each_node_breadth_first(rsp, rnp) {
if (rnp == rnp_root)
continue; /* printed unconditionally */
if (sync_rcu_preempt_exp_done(rnp))
continue;
pr_cont(" l=%u:%d-%d:%#lx/%c",
rnp->level, rnp->grplo, rnp->grphi,
rnp->expmask,
".T"[!!rnp->exp_tasks]);
}
pr_cont("\n");
}
rcu_for_each_leaf_node(rsp, rnp) {
mask = 1;
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
@ -3847,6 +3863,16 @@ void synchronize_sched_expedited(void)
struct rcu_node *rnp;
struct rcu_state *rsp = &rcu_sched_state;
/* If only one CPU, this is automatically a grace period. */
if (rcu_blocking_is_gp())
return;
/* If expedited grace periods are prohibited, fall back to normal. */
if (rcu_gp_is_normal()) {
wait_rcu_gp(call_rcu_sched);
return;
}
/* Take a snapshot of the sequence number. */
s = rcu_exp_gp_seq_snap(rsp);
@ -4135,7 +4161,7 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf)
rnp = rnp->parent;
if (rnp == NULL)
return;
raw_spin_lock(&rnp->lock); /* Interrupts already disabled. */
raw_spin_lock_rcu_node(rnp); /* Interrupts already disabled. */
rnp->qsmaskinit |= mask;
raw_spin_unlock(&rnp->lock); /* Interrupts remain disabled. */
}
@ -4152,7 +4178,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
struct rcu_node *rnp = rcu_get_root(rsp);
/* Set up local state, ensuring consistent view of global state. */
raw_spin_lock_irqsave(&rnp->lock, flags);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
@ -4179,7 +4205,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
struct rcu_node *rnp = rcu_get_root(rsp);
/* Set up local state, ensuring consistent view of global state. */
raw_spin_lock_irqsave(&rnp->lock, flags);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rdp->qlen_last_fqs_check = 0;
rdp->n_force_qs_snap = rsp->n_force_qs;
rdp->blimit = blimit;
@ -4198,8 +4224,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
*/
rnp = rdp->mynode;
mask = rdp->grpmask;
raw_spin_lock(&rnp->lock); /* irqs already disabled. */
smp_mb__after_unlock_lock();
raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
rnp->qsmaskinitnext |= mask;
rnp->expmaskinitnext |= mask;
if (!rdp->beenonline)
@ -4327,14 +4352,14 @@ static int __init rcu_spawn_gp_kthread(void)
t = kthread_create(rcu_gp_kthread, rsp, "%s", rsp->name);
BUG_ON(IS_ERR(t));
rnp = rcu_get_root(rsp);
raw_spin_lock_irqsave(&rnp->lock, flags);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rsp->gp_kthread = t;
if (kthread_prio) {
sp.sched_priority = kthread_prio;
sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
}
wake_up_process(t);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
wake_up_process(t);
}
rcu_spawn_nocb_kthreads();
rcu_spawn_boost_kthreads();
@ -4385,12 +4410,14 @@ static void __init rcu_init_levelspread(int *levelspread, const int *levelcnt)
/*
* Helper function for rcu_init() that initializes one rcu_state structure.
*/
static void __init rcu_init_one(struct rcu_state *rsp,
struct rcu_data __percpu *rda)
static void __init rcu_init_one(struct rcu_state *rsp)
{
static const char * const buf[] = RCU_NODE_NAME_INIT;
static const char * const fqs[] = RCU_FQS_NAME_INIT;
static const char * const exp[] = RCU_EXP_NAME_INIT;
static struct lock_class_key rcu_node_class[RCU_NUM_LVLS];
static struct lock_class_key rcu_fqs_class[RCU_NUM_LVLS];
static struct lock_class_key rcu_exp_class[RCU_NUM_LVLS];
static u8 fl_mask = 0x1;
int levelcnt[RCU_NUM_LVLS]; /* # nodes in each level. */
@ -4576,8 +4603,8 @@ void __init rcu_init(void)
rcu_bootup_announce();
rcu_init_geometry();
rcu_init_one(&rcu_bh_state, &rcu_bh_data);
rcu_init_one(&rcu_sched_state, &rcu_sched_data);
rcu_init_one(&rcu_bh_state);
rcu_init_one(&rcu_sched_state);
if (dump_tree)
rcu_dump_rcu_node_tree(&rcu_sched_state);
__rcu_init_preempt();

61
kernel/rcu/tree.h
View File

@ -178,6 +178,8 @@ struct rcu_node {
/* beginning of each expedited GP. */
unsigned long expmaskinitnext;
/* Online CPUs for next expedited GP. */
/* Any CPU that has ever been online will */
/* have its bit set. */
unsigned long grpmask; /* Mask to apply to parent qsmask. */
/* Only one bit will be set in this mask. */
int grplo; /* lowest-numbered CPU or group here. */
@ -384,6 +386,10 @@ struct rcu_data {
struct rcu_head oom_head;
#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
struct mutex exp_funnel_mutex;
atomic_long_t expedited_workdone0; /* # done by others #0. */
atomic_long_t expedited_workdone1; /* # done by others #1. */
atomic_long_t expedited_workdone2; /* # done by others #2. */
atomic_long_t expedited_workdone3; /* # done by others #3. */
/* 7) Callback offloading. */
#ifdef CONFIG_RCU_NOCB_CPU
@ -498,10 +504,6 @@ struct rcu_state {
/* End of fields guarded by barrier_mutex. */
unsigned long expedited_sequence; /* Take a ticket. */
atomic_long_t expedited_workdone0; /* # done by others #0. */
atomic_long_t expedited_workdone1; /* # done by others #1. */
atomic_long_t expedited_workdone2; /* # done by others #2. */
atomic_long_t expedited_workdone3; /* # done by others #3. */
atomic_long_t expedited_normal; /* # fallbacks to normal. */
atomic_t expedited_need_qs; /* # CPUs left to check in. */
wait_queue_head_t expedited_wq; /* Wait for check-ins. */
@ -545,6 +547,18 @@ struct rcu_state {
#define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */
#define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */
#ifndef RCU_TREE_NONCORE
static const char * const gp_state_names[] = {
"RCU_GP_IDLE",
"RCU_GP_WAIT_GPS",
"RCU_GP_DONE_GPS",
"RCU_GP_WAIT_FQS",
"RCU_GP_DOING_FQS",
"RCU_GP_CLEANUP",
"RCU_GP_CLEANED",
};
#endif /* #ifndef RCU_TREE_NONCORE */
extern struct list_head rcu_struct_flavors;
/* Sequence through rcu_state structures for each RCU flavor. */
@ -664,3 +678,42 @@ static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
#else /* #ifdef CONFIG_PPC */
#define smp_mb__after_unlock_lock() do { } while (0)
#endif /* #else #ifdef CONFIG_PPC */
/*
* Wrappers for the rcu_node::lock acquire.
*
* Because the rcu_nodes form a tree, the tree traversal locking will observe
* different lock values, this in turn means that an UNLOCK of one level
* followed by a LOCK of another level does not imply a full memory barrier;
* and most importantly transitivity is lost.
*
* In order to restore full ordering between tree levels, augment the regular
* lock acquire functions with smp_mb__after_unlock_lock().
*/
static inline void raw_spin_lock_rcu_node(struct rcu_node *rnp)
{
raw_spin_lock(&rnp->lock);
smp_mb__after_unlock_lock();
}
static inline void raw_spin_lock_irq_rcu_node(struct rcu_node *rnp)
{
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
}
#define raw_spin_lock_irqsave_rcu_node(rnp, flags) \
do { \
typecheck(unsigned long, flags); \
raw_spin_lock_irqsave(&(rnp)->lock, flags); \
smp_mb__after_unlock_lock(); \
} while (0)
static inline bool raw_spin_trylock_rcu_node(struct rcu_node *rnp)
{
bool locked = raw_spin_trylock(&rnp->lock);
if (locked)
smp_mb__after_unlock_lock();
return locked;
}

66
kernel/rcu/tree_plugin.h
View File

@ -63,8 +63,7 @@ static bool __read_mostly rcu_nocb_poll; /* Offload kthread are to poll. */
/*
* Check the RCU kernel configuration parameters and print informative
* messages about anything out of the ordinary. If you like #ifdef, you
* will love this function.
* messages about anything out of the ordinary.
*/
static void __init rcu_bootup_announce_oddness(void)
{
@ -147,8 +146,8 @@ static void __init rcu_bootup_announce(void)
* the corresponding expedited grace period will also be the end of the
* normal grace period.
*/
static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp,
unsigned long flags) __releases(rnp->lock)
static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp)
__releases(rnp->lock) /* But leaves rrupts disabled. */
{
int blkd_state = (rnp->gp_tasks ? RCU_GP_TASKS : 0) +
(rnp->exp_tasks ? RCU_EXP_TASKS : 0) +
@ -236,7 +235,7 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp,
rnp->gp_tasks = &t->rcu_node_entry;
if (!rnp->exp_tasks && (blkd_state & RCU_EXP_BLKD))
rnp->exp_tasks = &t->rcu_node_entry;
raw_spin_unlock(&rnp->lock);
raw_spin_unlock(&rnp->lock); /* rrupts remain disabled. */
/*
* Report the quiescent state for the expedited GP. This expedited
@ -251,7 +250,6 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp,
} else {
WARN_ON_ONCE(t->rcu_read_unlock_special.b.exp_need_qs);
}
local_irq_restore(flags);
}
/*
@ -286,12 +284,11 @@ static void rcu_preempt_qs(void)
* predating the current grace period drain, in other words, until
* rnp->gp_tasks becomes NULL.
*
* Caller must disable preemption.
* Caller must disable interrupts.
*/
static void rcu_preempt_note_context_switch(void)
{
struct task_struct *t = current;
unsigned long flags;
struct rcu_data *rdp;
struct rcu_node *rnp;
@ -301,8 +298,7 @@ static void rcu_preempt_note_context_switch(void)
/* Possibly blocking in an RCU read-side critical section. */
rdp = this_cpu_ptr(rcu_state_p->rda);
rnp = rdp->mynode;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_rcu_node(rnp);
t->rcu_read_unlock_special.b.blocked = true;
t->rcu_blocked_node = rnp;
@ -318,7 +314,7 @@ static void rcu_preempt_note_context_switch(void)
(rnp->qsmask & rdp->grpmask)
? rnp->gpnum
: rnp->gpnum + 1);
rcu_preempt_ctxt_queue(rnp, rdp, flags);
rcu_preempt_ctxt_queue(rnp, rdp);
} else if (t->rcu_read_lock_nesting < 0 &&
t->rcu_read_unlock_special.s) {
@ -450,20 +446,13 @@ void rcu_read_unlock_special(struct task_struct *t)
/*
* Remove this task from the list it blocked on. The task
* now remains queued on the rcu_node corresponding to
* the CPU it first blocked on, so the first attempt to
* acquire the task's rcu_node's ->lock will succeed.
* Keep the loop and add a WARN_ON() out of sheer paranoia.
* now remains queued on the rcu_node corresponding to the
* CPU it first blocked on, so there is no longer any need
* to loop. Retain a WARN_ON_ONCE() out of sheer paranoia.
*/
for (;;) {
rnp = t->rcu_blocked_node;
raw_spin_lock(&rnp->lock); /* irqs already disabled. */
smp_mb__after_unlock_lock();
if (rnp == t->rcu_blocked_node)
break;
WARN_ON_ONCE(1);
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
}
rnp = t->rcu_blocked_node;
raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
WARN_ON_ONCE(rnp != t->rcu_blocked_node);
empty_norm = !rcu_preempt_blocked_readers_cgp(rnp);
empty_exp = sync_rcu_preempt_exp_done(rnp);
smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */
@ -527,7 +516,7 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp)
unsigned long flags;
struct task_struct *t;
raw_spin_lock_irqsave(&rnp->lock, flags);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (!rcu_preempt_blocked_readers_cgp(rnp)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
@ -748,6 +737,12 @@ void synchronize_rcu_expedited(void)
struct rcu_state *rsp = rcu_state_p;
unsigned long s;
/* If expedited grace periods are prohibited, fall back to normal. */
if (rcu_gp_is_normal()) {
wait_rcu_gp(call_rcu);
return;
}
s = rcu_exp_gp_seq_snap(rsp);
rnp_unlock = exp_funnel_lock(rsp, s);
@ -788,7 +783,7 @@ EXPORT_SYMBOL_GPL(rcu_barrier);
*/
static void __init __rcu_init_preempt(void)
{
rcu_init_one(rcu_state_p, rcu_data_p);
rcu_init_one(rcu_state_p);
}
/*
@ -989,8 +984,7 @@ static int rcu_boost(struct rcu_node *rnp)
READ_ONCE(rnp->boost_tasks) == NULL)
return 0; /* Nothing left to boost. */
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
/*
* Recheck under the lock: all tasks in need of boosting
@ -1176,8 +1170,7 @@ static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
"rcub/%d", rnp_index);
if (IS_ERR(t))
return PTR_ERR(t);
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rnp->boost_kthread_task = t;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
sp.sched_priority = kthread_prio;
@ -1524,7 +1517,8 @@ static void rcu_prepare_for_idle(void)
struct rcu_state *rsp;
int tne;
if (IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL))
if (IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL) ||
rcu_is_nocb_cpu(smp_processor_id()))
return;
/* Handle nohz enablement switches conservatively. */
@ -1538,10 +1532,6 @@ static void rcu_prepare_for_idle(void)
if (!tne)
return;
/* If this is a no-CBs CPU, no callbacks, just return. */
if (rcu_is_nocb_cpu(smp_processor_id()))
return;
/*
* If a non-lazy callback arrived at a CPU having only lazy
* callbacks, invoke RCU core for the side-effect of recalculating
@ -1567,8 +1557,7 @@ static void rcu_prepare_for_idle(void)
if (!*rdp->nxttail[RCU_DONE_TAIL])
continue;
rnp = rdp->mynode;
raw_spin_lock(&rnp->lock); /* irqs already disabled. */
smp_mb__after_unlock_lock();
raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
needwake = rcu_accelerate_cbs(rsp, rnp, rdp);
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
if (needwake)
@ -2068,8 +2057,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
bool needwake;
struct rcu_node *rnp = rdp->mynode;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
needwake = rcu_start_future_gp(rnp, rdp, &c);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
if (needwake)

37
kernel/rcu/tree_trace.c
View File

@ -1,5 +1,5 @@
/*
* Read-Copy Update tracing for classic implementation
* Read-Copy Update tracing for hierarchical implementation.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@ -16,6 +16,7 @@
* http://www.gnu.org/licenses/gpl-2.0.html.
*
* Copyright IBM Corporation, 2008
* Author: Paul E. McKenney
*
* Papers: http://www.rdrop.com/users/paulmck/RCU
*
@ -33,9 +34,7 @@
#include <linux/sched.h>
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/completion.h>
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
@ -183,14 +182,20 @@ static const struct file_operations rcudata_fops = {
static int show_rcuexp(struct seq_file *m, void *v)
{
int cpu;
struct rcu_state *rsp = (struct rcu_state *)m->private;
struct rcu_data *rdp;
unsigned long s0 = 0, s1 = 0, s2 = 0, s3 = 0;
for_each_possible_cpu(cpu) {
rdp = per_cpu_ptr(rsp->rda, cpu);
s0 += atomic_long_read(&rdp->expedited_workdone0);
s1 += atomic_long_read(&rdp->expedited_workdone1);
s2 += atomic_long_read(&rdp->expedited_workdone2);
s3 += atomic_long_read(&rdp->expedited_workdone3);
}
seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n",
rsp->expedited_sequence,
atomic_long_read(&rsp->expedited_workdone0),
atomic_long_read(&rsp->expedited_workdone1),
atomic_long_read(&rsp->expedited_workdone2),
atomic_long_read(&rsp->expedited_workdone3),
rsp->expedited_sequence, s0, s1, s2, s3,
atomic_long_read(&rsp->expedited_normal),
atomic_read(&rsp->expedited_need_qs),
rsp->expedited_sequence / 2);
@ -319,7 +324,7 @@ static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
unsigned long gpmax;
struct rcu_node *rnp = &rsp->node[0];
raw_spin_lock_irqsave(&rnp->lock, flags);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
completed = READ_ONCE(rsp->completed);
gpnum = READ_ONCE(rsp->gpnum);
if (completed == gpnum)
@ -487,16 +492,4 @@ free_out:
debugfs_remove_recursive(rcudir);
return 1;
}
static void __exit rcutree_trace_cleanup(void)
{
debugfs_remove_recursive(rcudir);
}
module_init(rcutree_trace_init);
module_exit(rcutree_trace_cleanup);
MODULE_AUTHOR("Paul E. McKenney");
MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
MODULE_LICENSE("GPL");
device_initcall(rcutree_trace_init);

22
kernel/rcu/update.c
View File

@ -60,7 +60,12 @@ MODULE_ALIAS("rcupdate");
#endif
#define MODULE_PARAM_PREFIX "rcupdate."
#ifndef CONFIG_TINY_RCU
module_param(rcu_expedited, int, 0);
module_param(rcu_normal, int, 0);
static int rcu_normal_after_boot;
module_param(rcu_normal_after_boot, int, 0);
#endif /* #ifndef CONFIG_TINY_RCU */
#if defined(CONFIG_DEBUG_LOCK_ALLOC) && defined(CONFIG_PREEMPT_COUNT)
/**
@ -113,6 +118,17 @@ EXPORT_SYMBOL(rcu_read_lock_sched_held);
#ifndef CONFIG_TINY_RCU
/*
* Should expedited grace-period primitives always fall back to their
* non-expedited counterparts? Intended for use within RCU. Note
* that if the user specifies both rcu_expedited and rcu_normal, then
* rcu_normal wins.
*/
bool rcu_gp_is_normal(void)
{
return READ_ONCE(rcu_normal);
}
static atomic_t rcu_expedited_nesting =
ATOMIC_INIT(IS_ENABLED(CONFIG_RCU_EXPEDITE_BOOT) ? 1 : 0);
@ -157,8 +173,6 @@ void rcu_unexpedite_gp(void)
}
EXPORT_SYMBOL_GPL(rcu_unexpedite_gp);
#endif /* #ifndef CONFIG_TINY_RCU */
/*
* Inform RCU of the end of the in-kernel boot sequence.
*/
@ -166,8 +180,12 @@ void rcu_end_inkernel_boot(void)
{
if (IS_ENABLED(CONFIG_RCU_EXPEDITE_BOOT))
rcu_unexpedite_gp();
if (rcu_normal_after_boot)
WRITE_ONCE(rcu_normal, 1);
}
#endif /* #ifndef CONFIG_TINY_RCU */
#ifdef CONFIG_PREEMPT_RCU
/*

6
kernel/sched/core.c
View File

@ -3109,7 +3109,6 @@ static void __sched notrace __schedule(bool preempt)
cpu = smp_processor_id();
rq = cpu_rq(cpu);
rcu_note_context_switch();
prev = rq->curr;
/*
@ -3128,13 +3127,16 @@ static void __sched notrace __schedule(bool preempt)
if (sched_feat(HRTICK))
hrtick_clear(rq);
local_irq_disable();
rcu_note_context_switch();
/*
* Make sure that signal_pending_state()->signal_pending() below
* can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
* done by the caller to avoid the race with signal_wake_up().
*/
smp_mb__before_spinlock();
raw_spin_lock_irq(&rq->lock);
raw_spin_lock(&rq->lock);
lockdep_pin_lock(&rq->lock);
rq->clock_skip_update <<= 1; /* promote REQ to ACT */

2
lib/list_debug.c
View File

@ -37,7 +37,7 @@ void __list_add(struct list_head *new,
next->prev = new;
new->next = next;
new->prev = prev;
prev->next = new;
WRITE_ONCE(prev->next, new);
}
EXPORT_SYMBOL(__list_add);

9
tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
View File

@ -38,8 +38,6 @@
#
# Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
grace=120
T=/tmp/kvm-test-1-run.sh.$$
trap 'rm -rf $T' 0
touch $T
@ -152,7 +150,7 @@ fi
qemu_args="`specify_qemu_cpus "$QEMU" "$qemu_args" "$cpu_count"`"
# Generate architecture-specific and interaction-specific qemu arguments
qemu_args="$qemu_args `identify_qemu_args "$QEMU" "$builddir/console.log"`"
qemu_args="$qemu_args `identify_qemu_args "$QEMU" "$resdir/console.log"`"
# Generate qemu -append arguments
qemu_append="`identify_qemu_append "$QEMU"`"
@ -168,7 +166,7 @@ then
touch $resdir/buildonly
exit 0
fi
echo "NOTE: $QEMU either did not run or was interactive" > $builddir/console.log
echo "NOTE: $QEMU either did not run or was interactive" > $resdir/console.log
echo $QEMU $qemu_args -m 512 -kernel $resdir/bzImage -append \"$qemu_append $boot_args\" > $resdir/qemu-cmd
( $QEMU $qemu_args -m 512 -kernel $resdir/bzImage -append "$qemu_append $boot_args"; echo $? > $resdir/qemu-retval ) &
qemu_pid=$!
@ -214,7 +212,7 @@ then
else
break
fi
if test $kruntime -ge $((seconds + grace))
if test $kruntime -ge $((seconds + $TORTURE_SHUTDOWN_GRACE))
then
echo "!!! PID $qemu_pid hung at $kruntime vs. $seconds seconds" >> $resdir/Warnings 2>&1
kill -KILL $qemu_pid
@ -224,6 +222,5 @@ then
done
fi
cp $builddir/console.log $resdir
parse-torture.sh $resdir/console.log $title
parse-console.sh $resdir/console.log $title

22
tools/testing/selftests/rcutorture/bin/kvm.sh
View File

@ -42,6 +42,7 @@ TORTURE_DEFCONFIG=defconfig
TORTURE_BOOT_IMAGE=""
TORTURE_INITRD="$KVM/initrd"; export TORTURE_INITRD
TORTURE_KMAKE_ARG=""
TORTURE_SHUTDOWN_GRACE=180
TORTURE_SUITE=rcu
resdir=""
configs=""
@ -149,6 +150,11 @@ do
resdir=$2
shift
;;
--shutdown-grace)
checkarg --shutdown-grace "(seconds)" "$#" "$2" '^[0-9]*$' '^error'
TORTURE_SHUTDOWN_GRACE=$2
shift
;;
--torture)
checkarg --torture "(suite name)" "$#" "$2" '^\(lock\|rcu\)$' '^--'
TORTURE_SUITE=$2
@ -266,6 +272,7 @@ TORTURE_KMAKE_ARG="$TORTURE_KMAKE_ARG"; export TORTURE_KMAKE_ARG
TORTURE_QEMU_CMD="$TORTURE_QEMU_CMD"; export TORTURE_QEMU_CMD
TORTURE_QEMU_INTERACTIVE="$TORTURE_QEMU_INTERACTIVE"; export TORTURE_QEMU_INTERACTIVE
TORTURE_QEMU_MAC="$TORTURE_QEMU_MAC"; export TORTURE_QEMU_MAC
TORTURE_SHUTDOWN_GRACE="$TORTURE_SHUTDOWN_GRACE"; export TORTURE_SHUTDOWN_GRACE
TORTURE_SUITE="$TORTURE_SUITE"; export TORTURE_SUITE
if ! test -e $resdir
then
@ -307,10 +314,10 @@ awk < $T/cfgcpu.pack \
}
# Dump out the scripting required to run one test batch.
function dump(first, pastlast)
function dump(first, pastlast, batchnum)
{
print "echo ----Start batch: `date`";
print "echo ----Start batch: `date` >> " rd "/log";
print "echo ----Start batch " batchnum ": `date`";
print "echo ----Start batch " batchnum ": `date` >> " rd "/log";
jn=1
for (j = first; j < pastlast; j++) {
builddir=KVM "/b" jn
@ -371,25 +378,28 @@ END {
njobs = i;
nc = ncpus;
first = 0;
batchnum = 1;
# Each pass through the following loop considers one test.
for (i = 0; i < njobs; i++) {
if (ncpus == 0) {
# Sequential test specified, each test its own batch.
dump(i, i + 1);
dump(i, i + 1, batchnum);
first = i;
batchnum++;
} else if (nc < cpus[i] && i != 0) {
# Out of CPUs, dump out a batch.
dump(first, i);
dump(first, i, batchnum);
first = i;
nc = ncpus;
batchnum++;
}
# Account for the CPUs needed by the current test.
nc -= cpus[i];
}
# Dump the last batch.
if (ncpus != 0)
dump(first, i);
dump(first, i, batchnum);
}' >> $T/script
cat << ___EOF___ >> $T/script

41
tools/testing/selftests/rcutorture/bin/parse-console.sh
View File

@ -24,9 +24,6 @@
#
# Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
T=/tmp/abat-chk-badness.sh.$$
trap 'rm -f $T' 0
file="$1"
title="$2"
@ -36,9 +33,41 @@ if grep -Pq '\x00' < $file
then
print_warning Console output contains nul bytes, old qemu still running?
fi
egrep 'Badness|WARNING:|Warn|BUG|===========|Call Trace:|Oops:|Stall ended before state dump start' < $file | grep -v 'ODEBUG: ' | grep -v 'Warning: unable to open an initial console' > $T
if test -s $T
egrep 'Badness|WARNING:|Warn|BUG|===========|Call Trace:|Oops:|detected stalls on CPUs/tasks:|Stall ended before state dump start' < $file | grep -v 'ODEBUG: ' | grep -v 'Warning: unable to open an initial console' > $1.diags
if test -s $1.diags
then
print_warning Assertion failure in $file $title
cat $T
# cat $1.diags
summary=""
n_badness=`grep -c Badness $1`
if test "$n_badness" -ne 0
then
summary="$summary Badness: $n_badness"
fi
n_warn=`grep -v 'Warning: unable to open an initial console' $1 | egrep -c 'WARNING:|Warn'`
if test "$n_warn" -ne 0
then
summary="$summary Warnings: $n_warn"
fi
n_bugs=`egrep -c 'BUG|Oops:' $1`
if test "$n_bugs" -ne 0
then
summary="$summary Bugs: $n_bugs"
fi
n_calltrace=`grep -c 'Call Trace:' $1`
if test "$n_calltrace" -ne 0
then
summary="$summary Call Traces: $n_calltrace"
fi
n_lockdep=`grep -c =========== $1`
if test "$n_badness" -ne 0
then
summary="$summary lockdep: $n_badness"
fi
n_stalls=`egrep -c 'detected stalls on CPUs/tasks:|Stall ended before state dump start' $1`
if test "$n_stalls" -ne 0
then
summary="$summary Stalls: $n_stalls"
fi
print_warning Summary: $summary
fi

1
tools/testing/selftests/rcutorture/doc/TINY_RCU.txt
View File

@ -20,7 +20,6 @@ CONFIG_PROVE_RCU
CONFIG_NO_HZ_FULL_SYSIDLE
CONFIG_RCU_NOCB_CPU
CONFIG_RCU_USER_QS
Meaningless for TINY_RCU.

4
tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt
View File

@ -72,10 +72,6 @@ CONFIG_RCU_TORTURE_TEST_RUNNABLE
Always used in KVM testing.
CONFIG_RCU_USER_QS
Redundant with CONFIG_NO_HZ_FULL.
CONFIG_PREEMPT_RCU
CONFIG_TREE_RCU