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Merge branch 'rcu-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'rcu-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (21 commits)
  rcu: RCU-based detection of stalled CPUs for Classic RCU, fix
  rcu: RCU-based detection of stalled CPUs for Classic RCU
  rcu: add rcu_read_lock_sched() / rcu_read_unlock_sched()
  rcu: fix sparse shadowed variable warning
  doc/RCU: fix pseudocode in rcuref.txt
  rcuclassic: fix compiler warning
  rcu: use irq-safe locks
  rcuclassic: fix compilation NG
  rcu: fix locking cleanup fallout
  rcu: remove redundant ACCESS_ONCE definition from rcupreempt.c
  rcu: fix classic RCU locking cleanup lockdep problem
  rcu: trace fix possible mem-leak
  rcu: just rename call_rcu_bh instead of making it a macro
  rcu: remove list_for_each_rcu()
  rcu: fixes to include/linux/rcupreempt.h
  rcu: classic RCU locking and memory-barrier cleanups
  rcu: prevent console flood when one CPU sees another AWOL via RCU
  rcu, debug: detect stalled grace periods, cleanups
  rcu, debug: detect stalled grace periods
  rcu classic: new algorithm for callbacks-processing(v2)
  ...
This commit is contained in:
Linus Torvalds
2008-10-10 13:10:51 -07:00
parent c54dcd8ec9 cdbb92b31d
commit b922df7383
12 changed files with 337 additions and 134 deletions
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4
include/linux/compiler.h
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@ -190,7 +190,9 @@ extern void __chk_io_ptr(const volatile void __iomem *);
* ACCESS_ONCE() in different C statements.
*
* This macro does absolutely -nothing- to prevent the CPU from reordering,
* merging, or refetching absolutely anything at any time.
* merging, or refetching absolutely anything at any time. Its main intended
* use is to mediate communication between process-level code and irq/NMI
* handlers, all running on the same CPU.
*/
#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))

37
include/linux/rcuclassic.h
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@ -40,12 +40,21 @@
#include <linux/cpumask.h>
#include <linux/seqlock.h>
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
#define RCU_SECONDS_TILL_STALL_CHECK ( 3 * HZ) /* for rcp->jiffies_stall */
#define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ) /* for rcp->jiffies_stall */
#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
/* Global control variables for rcupdate callback mechanism. */
struct rcu_ctrlblk {
long cur; /* Current batch number. */
long completed; /* Number of the last completed batch */
int next_pending; /* Is the next batch already waiting? */
long pending; /* Number of the last pending batch */
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
unsigned long gp_start; /* Time at which GP started in jiffies. */
unsigned long jiffies_stall;
/* Time at which to check for CPU stalls. */
#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
int signaled;
@ -66,11 +75,7 @@ static inline int rcu_batch_after(long a, long b)
return (a - b) > 0;
}
/*
* Per-CPU data for Read-Copy UPdate.
* nxtlist - new callbacks are added here
* curlist - current batch for which quiescent cycle started if any
*/
/* Per-CPU data for Read-Copy UPdate. */
struct rcu_data {
/* 1) quiescent state handling : */
long quiescbatch; /* Batch # for grace period */
@ -78,12 +83,24 @@ struct rcu_data {
int qs_pending; /* core waits for quiesc state */
/* 2) batch handling */
long batch; /* Batch # for current RCU batch */
/*
* if nxtlist is not NULL, then:
* batch:
* The batch # for the last entry of nxtlist
* [*nxttail[1], NULL = *nxttail[2]):
* Entries that batch # <= batch
* [*nxttail[0], *nxttail[1]):
* Entries that batch # <= batch - 1
* [nxtlist, *nxttail[0]):
* Entries that batch # <= batch - 2
* The grace period for these entries has completed, and
* the other grace-period-completed entries may be moved
* here temporarily in rcu_process_callbacks().
*/
long batch;
struct rcu_head *nxtlist;
struct rcu_head **nxttail;
struct rcu_head **nxttail[3];
long qlen; /* # of queued callbacks */
struct rcu_head *curlist;
struct rcu_head **curtail;
struct rcu_head *donelist;
struct rcu_head **donetail;
long blimit; /* Upper limit on a processed batch */

14
include/linux/rculist.h
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@ -198,20 +198,6 @@ static inline void list_splice_init_rcu(struct list_head *list,
at->prev = last;
}
/**
* list_for_each_rcu - iterate over an rcu-protected list
* @pos: the &struct list_head to use as a loop cursor.
* @head: the head for your list.
*
* This list-traversal primitive may safely run concurrently with
* the _rcu list-mutation primitives such as list_add_rcu()
* as long as the traversal is guarded by rcu_read_lock().
*/
#define list_for_each_rcu(pos, head) \
for (pos = rcu_dereference((head)->next); \
prefetch(pos->next), pos != (head); \
pos = rcu_dereference(pos->next))
#define __list_for_each_rcu(pos, head) \
for (pos = rcu_dereference((head)->next); \
pos != (head); \

20
include/linux/rcupdate.h
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@ -132,6 +132,26 @@ struct rcu_head {
*/
#define rcu_read_unlock_bh() __rcu_read_unlock_bh()
/**
* rcu_read_lock_sched - mark the beginning of a RCU-classic critical section
*
* Should be used with either
* - synchronize_sched()
* or
* - call_rcu_sched() and rcu_barrier_sched()
* on the write-side to insure proper synchronization.
*/
#define rcu_read_lock_sched() preempt_disable()
/*
* rcu_read_unlock_sched - marks the end of a RCU-classic critical section
*
* See rcu_read_lock_sched for more information.
*/
#define rcu_read_unlock_sched() preempt_enable()
/**
* rcu_dereference - fetch an RCU-protected pointer in an
* RCU read-side critical section. This pointer may later

11
include/linux/rcupreempt.h
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@ -57,7 +57,13 @@ static inline void rcu_qsctr_inc(int cpu)
rdssp->sched_qs++;
}
#define rcu_bh_qsctr_inc(cpu)
#define call_rcu_bh(head, rcu) call_rcu(head, rcu)
/*
* Someone might want to pass call_rcu_bh as a function pointer.
* So this needs to just be a rename and not a macro function.
* (no parentheses)
*/
#define call_rcu_bh call_rcu
/**
* call_rcu_sched - Queue RCU callback for invocation after sched grace period.
@ -111,7 +117,6 @@ extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu);
struct softirq_action;
#ifdef CONFIG_NO_HZ
DECLARE_PER_CPU(struct rcu_dyntick_sched, rcu_dyntick_sched);
static inline void rcu_enter_nohz(void)
{
@ -126,8 +131,8 @@ static inline void rcu_exit_nohz(void)
{
static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
__get_cpu_var(rcu_dyntick_sched).dynticks++;
smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
WARN_ON_RATELIMIT(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1),
&rs);
}