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author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-11-14 16:30:30 +0900 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-11-14 16:30:30 +0900 |
commit | 5e30025a319910695f5010dc0fb53a23299da14d (patch) | |
tree | 4292bcf78de221c7de1774ccf5ad0ac5a9315c26 /include/linux/seqlock.h | |
parent | Merge branch 'x86-trace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (diff) | |
parent | block: Use u64_stats_init() to initialize seqcounts (diff) | |
download | linux-dev-5e30025a319910695f5010dc0fb53a23299da14d.tar.xz linux-dev-5e30025a319910695f5010dc0fb53a23299da14d.zip |
Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core locking changes from Ingo Molnar:
"The biggest changes:
- add lockdep support for seqcount/seqlocks structures, this
unearthed both bugs and required extra annotation.
- move the various kernel locking primitives to the new
kernel/locking/ directory"
* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
block: Use u64_stats_init() to initialize seqcounts
locking/lockdep: Mark __lockdep_count_forward_deps() as static
lockdep/proc: Fix lock-time avg computation
locking/doc: Update references to kernel/mutex.c
ipv6: Fix possible ipv6 seqlock deadlock
cpuset: Fix potential deadlock w/ set_mems_allowed
seqcount: Add lockdep functionality to seqcount/seqlock structures
net: Explicitly initialize u64_stats_sync structures for lockdep
locking: Move the percpu-rwsem code to kernel/locking/
locking: Move the lglocks code to kernel/locking/
locking: Move the rwsem code to kernel/locking/
locking: Move the rtmutex code to kernel/locking/
locking: Move the semaphore core to kernel/locking/
locking: Move the spinlock code to kernel/locking/
locking: Move the lockdep code to kernel/locking/
locking: Move the mutex code to kernel/locking/
hung_task debugging: Add tracepoint to report the hang
x86/locking/kconfig: Update paravirt spinlock Kconfig description
lockstat: Report avg wait and hold times
lockdep, x86/alternatives: Drop ancient lockdep fixup message
...
Diffstat (limited to 'include/linux/seqlock.h')
-rw-r--r-- | include/linux/seqlock.h | 79 |
1 files changed, 72 insertions, 7 deletions
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 21a209336e79..1e8a8b6e837d 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -34,6 +34,7 @@ #include <linux/spinlock.h> #include <linux/preempt.h> +#include <linux/lockdep.h> #include <asm/processor.h> /* @@ -44,10 +45,50 @@ */ typedef struct seqcount { unsigned sequence; +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lockdep_map dep_map; +#endif } seqcount_t; -#define SEQCNT_ZERO { 0 } -#define seqcount_init(x) do { *(x) = (seqcount_t) SEQCNT_ZERO; } while (0) +static inline void __seqcount_init(seqcount_t *s, const char *name, + struct lock_class_key *key) +{ + /* + * Make sure we are not reinitializing a held lock: + */ + lockdep_init_map(&s->dep_map, name, key, 0); + s->sequence = 0; +} + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +# define SEQCOUNT_DEP_MAP_INIT(lockname) \ + .dep_map = { .name = #lockname } \ + +# define seqcount_init(s) \ + do { \ + static struct lock_class_key __key; \ + __seqcount_init((s), #s, &__key); \ + } while (0) + +static inline void seqcount_lockdep_reader_access(const seqcount_t *s) +{ + seqcount_t *l = (seqcount_t *)s; + unsigned long flags; + + local_irq_save(flags); + seqcount_acquire_read(&l->dep_map, 0, 0, _RET_IP_); + seqcount_release(&l->dep_map, 1, _RET_IP_); + local_irq_restore(flags); +} + +#else +# define SEQCOUNT_DEP_MAP_INIT(lockname) +# define seqcount_init(s) __seqcount_init(s, NULL, NULL) +# define seqcount_lockdep_reader_access(x) +#endif + +#define SEQCNT_ZERO(lockname) { .sequence = 0, SEQCOUNT_DEP_MAP_INIT(lockname)} + /** * __read_seqcount_begin - begin a seq-read critical section (without barrier) @@ -76,6 +117,22 @@ repeat: } /** + * read_seqcount_begin_no_lockdep - 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 + * 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) +{ + unsigned ret = __read_seqcount_begin(s); + smp_rmb(); + return ret; +} + +/** * read_seqcount_begin - begin a seq-read critical section * @s: pointer to seqcount_t * Returns: count to be passed to read_seqcount_retry @@ -86,9 +143,8 @@ repeat: */ static inline unsigned read_seqcount_begin(const seqcount_t *s) { - unsigned ret = __read_seqcount_begin(s); - smp_rmb(); - return ret; + seqcount_lockdep_reader_access(s); + return read_seqcount_begin_no_lockdep(s); } /** @@ -108,6 +164,8 @@ static inline unsigned read_seqcount_begin(const seqcount_t *s) static inline unsigned raw_seqcount_begin(const seqcount_t *s) { unsigned ret = ACCESS_ONCE(s->sequence); + + seqcount_lockdep_reader_access(s); smp_rmb(); return ret & ~1; } @@ -152,14 +210,21 @@ static inline int read_seqcount_retry(const seqcount_t *s, unsigned start) * Sequence counter only version assumes that callers are using their * own mutexing. */ -static inline void write_seqcount_begin(seqcount_t *s) +static inline void write_seqcount_begin_nested(seqcount_t *s, int subclass) { s->sequence++; smp_wmb(); + seqcount_acquire(&s->dep_map, subclass, 0, _RET_IP_); +} + +static inline void write_seqcount_begin(seqcount_t *s) +{ + write_seqcount_begin_nested(s, 0); } static inline void write_seqcount_end(seqcount_t *s) { + seqcount_release(&s->dep_map, 1, _RET_IP_); smp_wmb(); s->sequence++; } @@ -188,7 +253,7 @@ typedef struct { */ #define __SEQLOCK_UNLOCKED(lockname) \ { \ - .seqcount = SEQCNT_ZERO, \ + .seqcount = SEQCNT_ZERO(lockname), \ .lock = __SPIN_LOCK_UNLOCKED(lockname) \ } |