Commit 226da0db authored by Linus Torvalds's avatar Linus Torvalds

Merge branch 'core-rcu-for-linus' of git://

Pull RCU changes from Ingo Molnar:
 "This is the v3.5 RCU tree from Paul E.  McKenney:

 1) A set of improvements and fixes to the RCU_FAST_NO_HZ feature (with
    more on the way for 3.6).  Posted to LKML: (commits 1-3 and 5), (commit 4), (commit 6), and (commit 7, combined with
       the other commits for the convenience of the tester).

 2) Changes to make rcu_barrier() avoid disrupting execution of CPUs
    that have no RCU callbacks.  Posted to LKML:

 3) A couple of commits that improve the efficiency of the interaction
    between preemptible RCU and the scheduler, these two being all that
    survived an abortive attempt to allow preemptible RCU's
    __rcu_read_lock() to be inlined.  The full set was posted to LKML at, and the first and third patches
    of that set remain.

 4) Lai Jiangshan's algorithmic implementation of SRCU, which includes
    call_srcu() and srcu_barrier().  A major feature of this new
    implementation is that synchronize_srcu() no longer disturbs the
    execution of other CPUs.  This work is based on earlier
    implementations by Peter Zijlstra and Paul E.  McKenney.  Posted to

 5) A number of miscellaneous bug fixes and improvements which were
    posted to LKML at: with
    subsequent updates posted to LKML."

* 'core-rcu-for-linus' of git:// (32 commits)
  rcu: Make rcu_barrier() less disruptive
  rcu: Explicitly initialize RCU_FAST_NO_HZ per-CPU variables
  rcu: Make RCU_FAST_NO_HZ handle timer migration
  rcu: Update RCU maintainership
  rcu: Make exit_rcu() more precise and consolidate
  rcu: Move PREEMPT_RCU preemption to switch_to() invocation
  rcu: Ensure that RCU_FAST_NO_HZ timers expire on correct CPU
  rcu: Add rcutorture test for call_srcu()
  rcu: Implement per-domain single-threaded call_srcu() state machine
  rcu: Use single value to handle expedited SRCU grace periods
  rcu: Improve srcu_readers_active_idx()'s cache locality
  rcu: Remove unused srcu_barrier()
  rcu: Implement a variant of Peter's SRCU algorithm
  rcu: Improve SRCU's wait_idx() comments
  rcu: Flip ->completed only once per SRCU grace period
  rcu: Increment upper bit only for srcu_read_lock()
  rcu: Remove fast check path from __synchronize_srcu()
  rcu: Direct algorithmic SRCU implementation
  rcu: Introduce rcutorture testing for rcu_barrier()
  timer: Fix mod_timer_pinned() header comment
parents 5ec29e31 2d84e023
......@@ -47,6 +47,16 @@ irqreader Says to invoke RCU readers from irq level. This is currently
permit this. (Or, more accurately, variants of RCU that do
-not- permit this know to ignore this variable.)
n_barrier_cbs If this is nonzero, RCU barrier testing will be conducted,
in which case n_barrier_cbs specifies the number of
RCU callbacks (and corresponding kthreads) to use for
this testing. The value cannot be negative. If you
specify this to be non-zero when torture_type indicates a
synchronous RCU implementation (one for which a member of
the synchronize_rcu() rather than the call_rcu() family is
used -- see the documentation for torture_type below), an
error will be reported and no testing will be carried out.
nfakewriters This is the number of RCU fake writer threads to run. Fake
writer threads repeatedly use the synchronous "wait for
current readers" function of the interface selected by
......@@ -188,7 +198,7 @@ OUTPUT
The statistics output is as follows:
rcu-torture:--- Start of test: nreaders=16 nfakewriters=4 stat_interval=30 verbose=0 test_no_idle_hz=1 shuffle_interval=3 stutter=5 irqreader=1 fqs_duration=0 fqs_holdoff=0 fqs_stutter=3 test_boost=1/0 test_boost_interval=7 test_boost_duration=4
rcu-torture: rtc: (null) ver: 155441 tfle: 0 rta: 155441 rtaf: 8884 rtf: 155440 rtmbe: 0 rtbke: 0 rtbre: 0 rtbf: 0 rtb: 0 nt: 3055767
rcu-torture: rtc: (null) ver: 155441 tfle: 0 rta: 155441 rtaf: 8884 rtf: 155440 rtmbe: 0 rtbe: 0 rtbke: 0 rtbre: 0 rtbf: 0 rtb: 0 nt: 3055767
rcu-torture: Reader Pipe: 727860534 34213 0 0 0 0 0 0 0 0 0
rcu-torture: Reader Batch: 727877838 17003 0 0 0 0 0 0 0 0 0
rcu-torture: Free-Block Circulation: 155440 155440 155440 155440 155440 155440 155440 155440 155440 155440 0
......@@ -230,6 +240,9 @@ o "rtmbe": A non-zero value indicates that rcutorture believes that
rcu_assign_pointer() and rcu_dereference() are not working
correctly. This value should be zero.
o "rtbe": A non-zero value indicates that one of the rcu_barrier()
family of functions is not working correctly.
o "rtbke": rcutorture was unable to create the real-time kthreads
used to force RCU priority inversion. This value should be zero.
......@@ -2333,18 +2333,100 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
See Documentation/blockdev/ramdisk.txt.
rcupdate.blimit= [KNL,BOOT]
rcutree.blimit= [KNL,BOOT]
Set maximum number of finished RCU callbacks to process
in one batch.
rcupdate.qhimark= [KNL,BOOT]
rcutree.qhimark= [KNL,BOOT]
Set threshold of queued
RCU callbacks over which batch limiting is disabled.
rcupdate.qlowmark= [KNL,BOOT]
rcutree.qlowmark= [KNL,BOOT]
Set threshold of queued RCU callbacks below which
batch limiting is re-enabled.
rcutree.rcu_cpu_stall_suppress= [KNL,BOOT]
Suppress RCU CPU stall warning messages.
rcutree.rcu_cpu_stall_timeout= [KNL,BOOT]
Set timeout for RCU CPU stall warning messages.
rcutorture.fqs_duration= [KNL,BOOT]
Set duration of force_quiescent_state bursts.
rcutorture.fqs_holdoff= [KNL,BOOT]
Set holdoff time within force_quiescent_state bursts.
rcutorture.fqs_stutter= [KNL,BOOT]
Set wait time between force_quiescent_state bursts.
rcutorture.irqreader= [KNL,BOOT]
Test RCU readers from irq handlers.
rcutorture.n_barrier_cbs= [KNL,BOOT]
Set callbacks/threads for rcu_barrier() testing.
rcutorture.nfakewriters= [KNL,BOOT]
Set number of concurrent RCU writers. These just
stress RCU, they don't participate in the actual
test, hence the "fake".
rcutorture.nreaders= [KNL,BOOT]
Set number of RCU readers.
rcutorture.onoff_holdoff= [KNL,BOOT]
Set time (s) after boot for CPU-hotplug testing.
rcutorture.onoff_interval= [KNL,BOOT]
Set time (s) between CPU-hotplug operations, or
zero to disable CPU-hotplug testing.
rcutorture.shuffle_interval= [KNL,BOOT]
Set task-shuffle interval (s). Shuffling tasks
allows some CPUs to go into dyntick-idle mode
during the rcutorture test.
rcutorture.shutdown_secs= [KNL,BOOT]
Set time (s) after boot system shutdown. This
is useful for hands-off automated testing.
rcutorture.stall_cpu= [KNL,BOOT]
Duration of CPU stall (s) to test RCU CPU stall
warnings, zero to disable.
rcutorture.stall_cpu_holdoff= [KNL,BOOT]
Time to wait (s) after boot before inducing stall.
rcutorture.stat_interval= [KNL,BOOT]
Time (s) between statistics printk()s.
rcutorture.stutter= [KNL,BOOT]
Time (s) to stutter testing, for example, specifying
five seconds causes the test to run for five seconds,
wait for five seconds, and so on. This tests RCU's
ability to transition abruptly to and from idle.
rcutorture.test_boost= [KNL,BOOT]
Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
"Maybe" means test if the RCU implementation
under test support RCU priority boosting.
rcutorture.test_boost_duration= [KNL,BOOT]
Duration (s) of each individual boost test.
rcutorture.test_boost_interval= [KNL,BOOT]
Interval (s) between each boost test.
rcutorture.test_no_idle_hz= [KNL,BOOT]
Test RCU's dyntick-idle handling. See also the
rcutorture.shuffle_interval parameter.
rcutorture.torture_type= [KNL,BOOT]
Specify the RCU implementation to test.
rcutorture.verbose= [KNL,BOOT]
Enable additional printk() statements.
rdinit= [KNL]
Format: <full_path>
Run specified binary instead of /init from the ramdisk,
......@@ -5598,14 +5598,13 @@ F: net/rds/
M: Dipankar Sarma <>
M: "Paul E. McKenney" <>
S: Supported
T: git git://
F: Documentation/RCU/
X: Documentation/RCU/torture.txt
F: include/linux/rcu*
F: include/linux/srcu*
F: kernel/rcu*
F: kernel/srcu*
X: kernel/rcutorture.c
......@@ -6122,6 +6121,15 @@ S: Maintained
F: include/linux/sl?b*.h
F: mm/sl?b.c
M: Lai Jiangshan <>
M: "Paul E. McKenney" <>
S: Supported
T: git git://
F: include/linux/srcu*
F: kernel/srcu*
M: Nicolas Pitre <>
S: Odd Fixes
......@@ -705,6 +705,7 @@ static void stack_proc(void *arg)
struct task_struct *from = current, *to = arg;
to->thread.saved_task = from;
switch_to(from, to, from);
......@@ -30,6 +30,7 @@
* This is only for internal list manipulation where we know
* the prev/next entries already!
static inline void __list_add_rcu(struct list_head *new,
struct list_head *prev, struct list_head *next)
......@@ -38,6 +39,10 @@ static inline void __list_add_rcu(struct list_head *new,
rcu_assign_pointer(list_next_rcu(prev), new);
next->prev = new;
extern void __list_add_rcu(struct list_head *new,
struct list_head *prev, struct list_head *next);
* list_add_rcu - add a new entry to rcu-protected list
......@@ -108,7 +113,7 @@ static inline void list_add_tail_rcu(struct list_head *new,
static inline void list_del_rcu(struct list_head *entry)
__list_del(entry->prev, entry->next);
entry->prev = LIST_POISON2;
......@@ -228,18 +233,43 @@ static inline void list_splice_init_rcu(struct list_head *list,
* list_first_entry_rcu - get the first element from a list
* Where are list_empty_rcu() and list_first_entry_rcu()?
* Implementing those functions following their counterparts list_empty() and
* list_first_entry() is not advisable because they lead to subtle race
* conditions as the following snippet shows:
* if (!list_empty_rcu(mylist)) {
* struct foo *bar = list_first_entry_rcu(mylist, struct foo, list_member);
* do_something(bar);
* }
* The list may not be empty when list_empty_rcu checks it, but it may be when
* list_first_entry_rcu rereads the ->next pointer.
* Rereading the ->next pointer is not a problem for list_empty() and
* list_first_entry() because they would be protected by a lock that blocks
* writers.
* See list_first_or_null_rcu for an alternative.
* list_first_or_null_rcu - get the first element from a list
* @ptr: the list head to take the element from.
* @type: the type of the struct this is embedded in.
* @member: the name of the list_struct within the struct.
* Note, that list is expected to be not empty.
* Note that if the list is empty, it returns NULL.
* This primitive may safely run concurrently with the _rcu list-mutation
* primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
#define list_first_entry_rcu(ptr, type, member) \
list_entry_rcu((ptr)->next, type, member)
#define list_first_or_null_rcu(ptr, type, member) \
({struct list_head *__ptr = (ptr); \
struct list_head __rcu *__next = list_next_rcu(__ptr); \
likely(__ptr != __next) ? container_of(__next, type, member) : NULL; \
* list_for_each_entry_rcu - iterate over rcu list of given type
......@@ -184,12 +184,14 @@ static inline int rcu_preempt_depth(void)
/* Internal to kernel */
extern void rcu_sched_qs(int cpu);
extern void rcu_bh_qs(int cpu);
extern void rcu_preempt_note_context_switch(void);
extern void rcu_check_callbacks(int cpu, int user);
struct notifier_block;
extern void rcu_idle_enter(void);
extern void rcu_idle_exit(void);
extern void rcu_irq_enter(void);
extern void rcu_irq_exit(void);
extern void exit_rcu(void);
* RCU_NONIDLE - Indicate idle-loop code that needs RCU readers
......@@ -922,6 +924,21 @@ void __kfree_rcu(struct rcu_head *head, unsigned long offset)
kfree_call_rcu(head, (rcu_callback)offset);
* Does the specified offset indicate that the corresponding rcu_head
* structure can be handled by kfree_rcu()?
#define __is_kfree_rcu_offset(offset) ((offset) < 4096)
* Helper macro for kfree_rcu() to prevent argument-expansion eyestrain.
#define __kfree_rcu(head, offset) \
do { \
BUILD_BUG_ON(!__is_kfree_rcu_offset(offset)); \
call_rcu(head, (void (*)(struct rcu_head *))(unsigned long)(offset)); \
} while (0)
* kfree_rcu() - kfree an object after a grace period.
* @ptr: pointer to kfree
......@@ -944,6 +961,9 @@ void __kfree_rcu(struct rcu_head *head, unsigned long offset)
* Note that the allowable offset might decrease in the future, for example,
* to allow something like kmem_cache_free_rcu().
* The BUILD_BUG_ON check must not involve any function calls, hence the
* checks are done in macros here.
#define kfree_rcu(ptr, rcu_head) \
__kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head))
......@@ -87,14 +87,6 @@ static inline void kfree_call_rcu(struct rcu_head *head,
static inline void rcu_preempt_note_context_switch(void)
static inline void exit_rcu(void)
static inline int rcu_needs_cpu(int cpu)
return 0;
......@@ -102,8 +94,6 @@ static inline int rcu_needs_cpu(int cpu)
#else /* #ifdef CONFIG_TINY_RCU */
void rcu_preempt_note_context_switch(void);
extern void exit_rcu(void);
int rcu_preempt_needs_cpu(void);
static inline int rcu_needs_cpu(int cpu)
......@@ -116,7 +106,6 @@ static inline int rcu_needs_cpu(int cpu)
static inline void rcu_note_context_switch(int cpu)
......@@ -45,18 +45,6 @@ static inline void rcu_virt_note_context_switch(int cpu)
extern void exit_rcu(void);
#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
static inline void exit_rcu(void)
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
extern void synchronize_rcu_bh(void);
extern void synchronize_sched_expedited(void);
extern void synchronize_rcu_expedited(void);
......@@ -98,13 +86,6 @@ extern void rcu_force_quiescent_state(void);
extern void rcu_bh_force_quiescent_state(void);
extern void rcu_sched_force_quiescent_state(void);
/* A context switch is a grace period for RCU-sched and RCU-bh. */
static inline int rcu_blocking_is_gp(void)
might_sleep(); /* Check for RCU read-side critical section. */
return num_online_cpus() == 1;
extern void rcu_scheduler_starting(void);
extern int rcu_scheduler_active __read_mostly;
......@@ -1905,12 +1905,22 @@ static inline void rcu_copy_process(struct task_struct *p)
static inline void rcu_switch_from(struct task_struct *prev)
if (prev->rcu_read_lock_nesting != 0)
static inline void rcu_copy_process(struct task_struct *p)
static inline void rcu_switch_from(struct task_struct *prev)
......@@ -29,26 +29,35 @@
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include <linux/workqueue.h>
struct srcu_struct_array {
int c[2];
unsigned long c[2];
unsigned long seq[2];
struct rcu_batch {
struct rcu_head *head, **tail;
struct srcu_struct {
int completed;
unsigned completed;
struct srcu_struct_array __percpu *per_cpu_ref;
struct mutex mutex;
spinlock_t queue_lock; /* protect ->batch_queue, ->running */
bool running;
/* callbacks just queued */
struct rcu_batch batch_queue;
/* callbacks try to do the first check_zero */
struct rcu_batch batch_check0;
/* callbacks done with the first check_zero and the flip */
struct rcu_batch batch_check1;
struct rcu_batch batch_done;
struct delayed_work work;
struct lockdep_map dep_map;
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
#define srcu_barrier() barrier()
#else /* #ifndef CONFIG_PREEMPT */
#define srcu_barrier()
#endif /* #else #ifndef CONFIG_PREEMPT */
int __init_srcu_struct(struct srcu_struct *sp, const char *name,
......@@ -67,12 +76,33 @@ int init_srcu_struct(struct srcu_struct *sp);
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
* call_srcu() - Queue a callback for invocation after an SRCU grace period
* @sp: srcu_struct in queue the callback
* @head: structure to be used for queueing the SRCU callback.
* @func: function to be invoked after the SRCU grace period
* The callback function will be invoked some time after a full SRCU
* grace period elapses, in other words after all pre-existing SRCU
* read-side critical sections have completed. However, the callback
* function might well execute concurrently with other SRCU read-side
* critical sections that started after call_srcu() was invoked. SRCU
* read-side critical sections are delimited by srcu_read_lock() and
* srcu_read_unlock(), and may be nested.
* The callback will be invoked from process context, but must nevertheless
* be fast and must not block.
void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
void (*func)(struct rcu_head *head));
void cleanup_srcu_struct(struct srcu_struct *sp);
int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
void synchronize_srcu(struct srcu_struct *sp);
void synchronize_srcu_expedited(struct srcu_struct *sp);
long srcu_batches_completed(struct srcu_struct *sp);
void srcu_barrier(struct srcu_struct *sp);
......@@ -292,6 +292,8 @@ TRACE_EVENT(rcu_dyntick,
* "More callbacks": Still more callbacks, try again to clear them out.
* "Callbacks drained": All callbacks processed, off to dyntick idle!
* "Timer": Timer fired to cause CPU to continue processing callbacks.
* "Demigrate": Timer fired on wrong CPU, woke up correct CPU.
* "Cleanup after idle": Idle exited, timer canceled.
......@@ -458,6 +458,33 @@ config RCU_FANOUT
Select a specific number if testing RCU itself.
Take the default if unsure.
int "Tree-based hierarchical RCU leaf-level fanout value"
range 2 RCU_FANOUT if 64BIT
range 2 RCU_FANOUT if !64BIT
default 16
This option controls the leaf-level fanout of hierarchical
implementations of RCU, and allows trading off cache misses
against lock contention. Systems that synchronize their
scheduling-clock interrupts for energy-efficiency reasons will
want the default because the smaller leaf-level fanout keeps
lock contention levels acceptably low. Very large systems
(hundreds or thousands of CPUs) will instead want to set this
value to the maximum value possible in order to reduce the
number of cache misses incurred during RCU's grace-period
initialization. These systems tend to run CPU-bound, and thus
are not helped by synchronized interrupts, and thus tend to
skew them, which reduces lock contention enough that large
leaf-level fanouts work well.
Select a specific number if testing RCU itself.
Select the maximum permissible value for large systems.
Take the default if unsure.
bool "Disable tree-based hierarchical RCU auto-balancing"
......@@ -515,10 +542,25 @@ config RCU_BOOST_PRIO
depends on RCU_BOOST
default 1
This option specifies the real-time priority to which preempted
RCU readers are to be boosted. If you are working with CPU-bound
real-time applications, you should specify a priority higher then
the highest-priority CPU-bound application.
This option specifies the real-time priority to which long-term
preempted RCU readers are to be boosted. If you are working
with a real-time application that has one or more CPU-bound
threads running at a real-time priority level, you should set
RCU_BOOST_PRIO to a priority higher then the highest-priority
real-time CPU-bound thread. The default RCU_BOOST_PRIO value
of 1 is appropriate in the common case, which is real-time
applications that do not have any CPU-bound threads.
Some real-time applications might not have a single real-time
thread that saturates a given CPU, but instead might have
multiple real-time threads that, taken together, fully utilize
that CPU. In this case, you should set RCU_BOOST_PRIO to
a priority higher than the lowest-priority thread that is
conspiring to prevent the CPU from running any non-real-time
tasks. For example, if one thread at priority 10 and another
thread at priority 5 are between themselves fully consuming
the CPU time on a given CPU, then RCU_BOOST_PRIO should be
set to priority 6 or higher.
Specify the real-time priority, or take the default if unsure.
......@@ -51,6 +51,34 @@
#include "rcu.h"
* Check for a task exiting while in a preemptible-RCU read-side
* critical section, clean up if so. No need to issue warnings,
* as debug_check_no_locks_held() already does this if lockdep
* is enabled.
void exit_rcu(void)
struct task_struct *t = current;
if (likely(list_empty(&current->rcu_node_entry)))
t->rcu_read_lock_nesting = 1;
t->rcu_read_unlock_special = RCU_READ_UNLOCK_BLOCKED;
#else /* #ifdef CONFIG_PREEMPT_RCU */
void exit_rcu(void)
#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
static struct lock_class_key rcu_lock_key;
struct lockdep_map rcu_lock_map =
......@@ -851,22 +851,6 @@ int rcu_preempt_needs_cpu(void)
return rcu_preempt_ctrlblk.rcb.rcucblist != NULL;
* Check for a task exiting while in a preemptible -RCU read-side
* critical section, clean up if so. No need to issue warnings,
* as debug_check_no_locks_held() already does this if lockdep
* is enabled.
void exit_rcu(void)
struct task_struct *t = current;
if (t->rcu_read_lock_nesting == 0)
t->rcu_read_lock_nesting = 1;
#else /* #ifdef CONFIG_TINY_PREEMPT_RCU */
This diff is collapsed.
This diff is collapsed.
......@@ -29,18 +29,14 @@
#include <linux/seqlock.h>
* Define shape of hierarchy based on NR_CPUS and CONFIG_RCU_FANOUT.
* Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and
* In theory, it should be possible to add more levels straightforwardly.
* In practice, this did work well going from three levels to four.
* Of course, your mileage may vary.
#define MAX_RCU_LVLS 4
#define RCU_FANOUT_LEAF 16
#else /* #if CONFIG_RCU_FANOUT > 16 */
#endif /* #else #if CONFIG_RCU_FANOUT > 16 */
......@@ -371,6 +367,17 @@ struct rcu_state {
raw_spinlock_t onofflock; /* exclude on/offline and */
/* starting new GP. */
struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */
/* need a grace period. */
struct rcu_head **orphan_nxttail; /* Tail of above. */
struct rcu_head *orphan_donelist; /* Orphaned callbacks that */
/* are ready to invoke. */
struct rcu_head **orphan_donetail; /* Tail of above. */
long qlen_lazy; /* Number of lazy callbacks. */
long qlen; /* Total number of callbacks. */
struct task_struct *rcu_barrier_in_progress;
/* Task doing rcu_barrier(), */
/* or NULL if no barrier. */
raw_spinlock_t fqslock; /* Only one task forcing */
/* quiescent states. */
unsigned long jiffies_force_qs; /* Time at which to invoke */
......@@ -423,7 +430,6 @@ DECLARE_PER_CPU(char, rcu_cpu_has_work);
/* Forward declarations for rcutree_plugin.h */
static void rcu_bootup_announce(void);
long rcu_batches_completed(void);
static void rcu_preempt_note_context_switch(int cpu);
static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
......@@ -471,6 +477,7 @@ static void __cpuinit rcu_prepare_kthreads(int cpu);
static void rcu_prepare_for_idle_init(int cpu);
static void rcu_cleanup_after_idle(int cpu);
static void rcu_prepare_for_idle(int cpu);
static void rcu_idle_count_callbacks_posted(void);
static void print_cpu_stall_info_begin(void);
static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
static void print_cpu_stall_info_end(void);
......@@ -153,7 +153,7 @@ static void rcu_preempt_qs(int cpu)
* Caller must disable preemption.
static void rcu_preempt_note_context_switch(int cpu)
void rcu_preempt_note_context_switch(void)
struct task_struct *t = current;
unsigned long flags;
......@@ -164,7 +164,7 @@ static void rcu_preempt_note_context_switch(int cpu)
(t->rcu_read_unlock_special & RCU_READ_UNLOCK_BLOCKED) == 0) {
/* Possibly blocking in an RCU read-side critical section. */
rdp = per_cpu_ptr(rcu_preempt_state.rda, cpu);
rdp = __this_cpu_ptr(rcu_preempt_state.rda);
rnp = rdp->mynode;
raw_spin_lock_irqsave(&rnp->lock, flags);
t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BLOCKED;
......@@ -228,7 +228,7 @@ static void rcu_preempt_note_context_switch(int cpu)
* means that we continue to block the current grace period.
......@@ -969,22 +969,6 @@ static void __init __rcu_init_preempt(void)
rcu_init_one(&rcu_preempt_state, &rcu_preempt_data);
* Check for a task exiting while in a preemptible-RCU read-side
* critical section, clean up if so. No need to issue warnings,
* as debug_check_no_locks_held() already does this if lockdep
* is enabled.
void exit_rcu(void)
struct task_struct *t = current;
if (t->rcu_read_lock_nesting == 0)
t->rcu_read_lock_nesting = 1;
#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
static struct rcu_state *rcu_state = &rcu_sched_state;
......@@ -1017,14 +1001,6 @@ void rcu_force_quiescent_state(void)
* Because preemptible RCU does not exist, we never have to check for
* CPUs being in quiescent states.
static void rcu_preempt_note_context_switch(int cpu)
* Because preemptible RCU does not exist, there are never any preempted
* RCU readers.
......@@ -1938,6 +1914,14 @@ static void rcu_prepare_for_idle(int cpu)
* Don't bother keeping a running count of the number of RCU callbacks
* posted because CONFIG_RCU_FAST_NO_HZ=n.
static void rcu_idle_count_callbacks_posted(void)
#else /* #if !defined(CONFIG_RCU_FAST_NO_HZ) */
......@@ -1978,11 +1962,20 @@ static void rcu_prepare_for_idle(int cpu)
#define RCU_IDLE_GP_DELAY 6 /* Roughly one grace period. */
#define RCU_IDLE_LAZY_GP_DELAY (6 * HZ) /* Roughly six seconds. */
/* Loop counter for rcu_prepare_for_idle(). */
static DEFINE_PER_CPU(int, rcu_dyntick_drain);
/* If rcu_dyntick_holdoff==jiffies, don't try to enter dyntick-idle mode. */
static DEFINE_PER_CPU(unsigned long, rcu_dyntick_holdoff);
static DEFINE_PER_CPU(struct hrtimer, rcu_idle_gp_timer);
static ktime_t rcu_idle_gp_wait; /* If some non-lazy callbacks. */
static ktime_t rcu_idle_lazy_gp_wait; /* If only lazy callbacks. */
/* Timer to awaken the CPU if it enters dyntick-idle mode with callbacks. */
static DEFINE_PER_CPU(struct timer_list, rcu_idle_gp_timer);
/* Scheduled expiry time for rcu_idle_gp_timer to allow reposting. */
static DEFINE_PER_CPU(unsigned long, rcu_idle_gp_timer_expires);
/* Enable special processing on first attempt to enter dyntick-idle mode. */
static DEFINE_PER_CPU(bool, rcu_idle_first_pass);
/* Running count of non-lazy callbacks posted, never decremented. */