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Commit 9b6c4ea9 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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

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
parents 93a11c8f 7a06c41c

arch/x86/vdso/vclock_gettime.c

+4 −4
Original line number Original line Diff line number Diff line
@@ -178,7 +178,7 @@ notrace static int __always_inline do_realtime(struct timespec *ts) 




	ts->tv_nsec = 0;

	ts->tv_nsec = 0;

	do {

	do {

		seq = read_seqcount_begin_no_lockdep(&gtod->seq);

		seq = raw_read_seqcount_begin(&gtod->seq);

		mode = gtod->clock.vclock_mode;

		mode = gtod->clock.vclock_mode;

		ts->tv_sec = gtod->wall_time_sec;

		ts->tv_sec = gtod->wall_time_sec;

		ns = gtod->wall_time_snsec;

		ns = gtod->wall_time_snsec;
@@ -198,7 +198,7 @@ notrace static int do_monotonic(struct timespec *ts) 




	ts->tv_nsec = 0;

	ts->tv_nsec = 0;

	do {

	do {

		seq = read_seqcount_begin_no_lockdep(&gtod->seq);

		seq = raw_read_seqcount_begin(&gtod->seq);

		mode = gtod->clock.vclock_mode;

		mode = gtod->clock.vclock_mode;

		ts->tv_sec = gtod->monotonic_time_sec;

		ts->tv_sec = gtod->monotonic_time_sec;

		ns = gtod->monotonic_time_snsec;

		ns = gtod->monotonic_time_snsec;
@@ -214,7 +214,7 @@ notrace static int do_realtime_coarse(struct timespec *ts) 
{

{

	unsigned long seq;

	unsigned long seq;

	do {

	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_sec = gtod->wall_time_coarse.tv_sec;

		ts->tv_nsec = gtod->wall_time_coarse.tv_nsec;

		ts->tv_nsec = gtod->wall_time_coarse.tv_nsec;

	} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));

	} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
@@ -225,7 +225,7 @@ notrace static int do_monotonic_coarse(struct timespec *ts) 
{

{

	unsigned long seq;

	unsigned long seq;

	do {

	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_sec = gtod->monotonic_time_coarse.tv_sec;

		ts->tv_nsec = gtod->monotonic_time_coarse.tv_nsec;

		ts->tv_nsec = gtod->monotonic_time_coarse.tv_nsec;

	} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));

	} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));

include/linux/seqlock.h

+19 −8
Original line number Original line Diff line number Diff line
@@ -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

 * @s: pointer to seqcount_t

 * Returns: count to be passed to read_seqcount_retry

 * 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

 * seqcount, but without any lockdep checking. Validity of the critical

 * section is tested by checking read_seqcount_retry function.

 * 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);

	unsigned ret = __read_seqcount_begin(s);

	smp_rmb();

	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)

static inline unsigned read_seqcount_begin(const seqcount_t *s)

{

{

	seqcount_lockdep_reader_access(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

 * Sequence counter only version assumes that callers are using their

 * own mutexing.

 * own mutexing.

 */

 */

static inline void write_seqcount_begin_nested(seqcount_t *s, int subclass)

static inline void write_seqcount_begin_nested(seqcount_t *s, int subclass)

{

{

	s->sequence++;

	raw_write_seqcount_begin(s);

	smp_wmb();

	seqcount_acquire(&s->dep_map, subclass, 0, _RET_IP_);

	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)

static inline void write_seqcount_end(seqcount_t *s)

{

{

	seqcount_release(&s->dep_map, 1, _RET_IP_);

	seqcount_release(&s->dep_map, 1, _RET_IP_);

	smp_wmb();

	raw_write_seqcount_end(s);

	s->sequence++;

}

}





/**

/**

kernel/time/sched_clock.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -74,7 +74,7 @@ unsigned long long notrace sched_clock(void) 
		return cd.epoch_ns;

		return cd.epoch_ns;





	do {

	do {

		seq = read_seqcount_begin(&cd.seq);

		seq = raw_read_seqcount_begin(&cd.seq);

		epoch_cyc = cd.epoch_cyc;

		epoch_cyc = cd.epoch_cyc;

		epoch_ns = cd.epoch_ns;

		epoch_ns = cd.epoch_ns;

	} while (read_seqcount_retry(&cd.seq, seq));

	} while (read_seqcount_retry(&cd.seq, seq));
@@ -99,10 +99,10 @@ static void notrace update_sched_clock(void) 
			  cd.mult, cd.shift);

			  cd.mult, cd.shift);





	raw_local_irq_save(flags);

	raw_local_irq_save(flags);

	write_seqcount_begin(&cd.seq);

	raw_write_seqcount_begin(&cd.seq);

	cd.epoch_ns = ns;

	cd.epoch_ns = ns;

	cd.epoch_cyc = cyc;

	cd.epoch_cyc = cyc;

	write_seqcount_end(&cd.seq);

	raw_write_seqcount_end(&cd.seq);

	raw_local_irq_restore(flags);

	raw_local_irq_restore(flags);

}

}