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Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu

Browse source 
Pull RCU changes from Paul E. McKenney:

 - 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.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2016-01-06 11:41:48 +01:00
commit 3104fb3dd4
34 changed files with 7550 additions and 285 deletions
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id="tspan3019">Inconsistent Data OK</tspan></text>
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id="tspan3025">Read-Mostly, Need Consistent Data</tspan></text>
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sodipodi:linespacing="125%">Update-Mostly, Need Consistent Data</text>
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style="font-size:427.63009644px;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;text-align:center;line-height:125%;writing-mode:lr-tb;text-anchor:middle;font-family:Nimbus Sans L;-inkscape-font-specification:Nimbus Sans L"
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sodipodi:linespacing="125%">(1) Provide Existence Guarantees For Update-Friendly Mechanisms</text>
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sodipodi:linespacing="125%">(2) Provide Wait-Free Read-Side Primitives for Real-Time Use)</text>
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sodipodi:linespacing="125%">(RCU is Very Unlikely to be the Right Tool For The Job, But it Can:</text>
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2897
Documentation/RCU/Design/Requirements/Requirements.html Normal file
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2741
Documentation/RCU/Design/Requirements/Requirements.htmlx Normal file
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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