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

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Pull locking fixes from Ingo Molnar:
 "Two fixes from lockdep coverage of seqlocks, which fix deadlocks on
  lockdep-enabled ARM systems"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched_clock: Disable seqlock lockdep usage in sched_clock()
  seqlock: Use raw_ prefix instead of _no_lockdep
This commit is contained in:
Linus Torvalds 2014-01-16 08:31:55 +07:00
commit 9b6c4ea95f
3 changed files with 26 additions and 15 deletions
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8
arch/x86/vdso/vclock_gettime.c
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@ -178,7 +178,7 @@ notrace static int __always_inline do_realtime(struct timespec *ts)
ts->tv_nsec = 0;
do {
seq = read_seqcount_begin_no_lockdep(&gtod->seq);
seq = raw_read_seqcount_begin(&gtod->seq);
mode = gtod->clock.vclock_mode;
ts->tv_sec = gtod->wall_time_sec;
ns = gtod->wall_time_snsec;
@ -198,7 +198,7 @@ notrace static int do_monotonic(struct timespec *ts)
ts->tv_nsec = 0;
do {
seq = read_seqcount_begin_no_lockdep(&gtod->seq);
seq = raw_read_seqcount_begin(&gtod->seq);
mode = gtod->clock.vclock_mode;
ts->tv_sec = gtod->monotonic_time_sec;
ns = gtod->monotonic_time_snsec;
@ -214,7 +214,7 @@ notrace static int do_realtime_coarse(struct timespec *ts)
{
unsigned long seq;
do {
seq = read_seqcount_begin_no_lockdep(&gtod->seq);
seq = raw_read_seqcount_begin(&gtod->seq);
ts->tv_sec = gtod->wall_time_coarse.tv_sec;
ts->tv_nsec = gtod->wall_time_coarse.tv_nsec;
} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
@ -225,7 +225,7 @@ notrace static int do_monotonic_coarse(struct timespec *ts)
{
unsigned long seq;
do {
seq = read_seqcount_begin_no_lockdep(&gtod->seq);
seq = raw_read_seqcount_begin(&gtod->seq);
ts->tv_sec = gtod->monotonic_time_coarse.tv_sec;
ts->tv_nsec = gtod->monotonic_time_coarse.tv_nsec;
} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));

27
include/linux/seqlock.h
View File

@ -117,15 +117,15 @@ static inline unsigned __read_seqcount_begin(const seqcount_t *s)
}
/**
* read_seqcount_begin_no_lockdep - start seq-read critical section w/o lockdep
* raw_read_seqcount_begin - start seq-read critical section w/o lockdep
* @s: pointer to seqcount_t
* Returns: count to be passed to read_seqcount_retry
*
* read_seqcount_begin_no_lockdep opens a read critical section of the given
* raw_read_seqcount_begin opens a read critical section of the given
* seqcount, but without any lockdep checking. Validity of the critical
* section is tested by checking read_seqcount_retry function.
*/
static inline unsigned read_seqcount_begin_no_lockdep(const seqcount_t *s)
static inline unsigned raw_read_seqcount_begin(const seqcount_t *s)
{
unsigned ret = __read_seqcount_begin(s);
smp_rmb();
@ -144,7 +144,7 @@ static inline unsigned read_seqcount_begin_no_lockdep(const seqcount_t *s)
static inline unsigned read_seqcount_begin(const seqcount_t *s)
{
seqcount_lockdep_reader_access(s);
return read_seqcount_begin_no_lockdep(s);
return raw_read_seqcount_begin(s);
}
/**
@ -206,14 +206,26 @@ static inline int read_seqcount_retry(const seqcount_t *s, unsigned start)
}
static inline void raw_write_seqcount_begin(seqcount_t *s)
{
s->sequence++;
smp_wmb();
}
static inline void raw_write_seqcount_end(seqcount_t *s)
{
smp_wmb();
s->sequence++;
}
/*
* Sequence counter only version assumes that callers are using their
* own mutexing.
*/
static inline void write_seqcount_begin_nested(seqcount_t *s, int subclass)
{
s->sequence++;
smp_wmb();
raw_write_seqcount_begin(s);
seqcount_acquire(&s->dep_map, subclass, 0, _RET_IP_);
}
@ -225,8 +237,7 @@ static inline void write_seqcount_begin(seqcount_t *s)
static inline void write_seqcount_end(seqcount_t *s)
{
seqcount_release(&s->dep_map, 1, _RET_IP_);
smp_wmb();
s->sequence++;
raw_write_seqcount_end(s);
}
/**

6
kernel/time/sched_clock.c
View File

@ -74,7 +74,7 @@ unsigned long long notrace sched_clock(void)
return cd.epoch_ns;
do {
seq = read_seqcount_begin(&cd.seq);
seq = raw_read_seqcount_begin(&cd.seq);
epoch_cyc = cd.epoch_cyc;
epoch_ns = cd.epoch_ns;
} while (read_seqcount_retry(&cd.seq, seq));
@ -99,10 +99,10 @@ static void notrace update_sched_clock(void)
cd.mult, cd.shift);
raw_local_irq_save(flags);
write_seqcount_begin(&cd.seq);
raw_write_seqcount_begin(&cd.seq);
cd.epoch_ns = ns;
cd.epoch_cyc = cyc;
write_seqcount_end(&cd.seq);
raw_write_seqcount_end(&cd.seq);
raw_local_irq_restore(flags);
}