diff options
Diffstat (limited to 'lib/lockref.c')
| -rw-r--r-- | lib/lockref.c | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/lib/lockref.c b/lib/lockref.c index 677d036cf3c7..d2b123f8456b 100644 --- a/lib/lockref.c +++ b/lib/lockref.c @@ -1,7 +1,23 @@ #include <linux/export.h> #include <linux/lockref.h> -#ifdef CONFIG_CMPXCHG_LOCKREF +#if USE_CMPXCHG_LOCKREF + +/* + * Allow weakly-ordered memory architectures to provide barrier-less + * cmpxchg semantics for lockref updates. + */ +#ifndef cmpxchg64_relaxed +# define cmpxchg64_relaxed cmpxchg64 +#endif + +/* + * Allow architectures to override the default cpu_relax() within CMPXCHG_LOOP. + * This is useful for architectures with an expensive cpu_relax(). + */ +#ifndef arch_mutex_cpu_relax +# define arch_mutex_cpu_relax() cpu_relax() +#endif /* * Note that the "cmpxchg()" reloads the "old" value for the @@ -14,12 +30,13 @@ while (likely(arch_spin_value_unlocked(old.lock.rlock.raw_lock))) { \ struct lockref new = old, prev = old; \ CODE \ - old.lock_count = cmpxchg64(&lockref->lock_count, \ - old.lock_count, new.lock_count); \ + old.lock_count = cmpxchg64_relaxed(&lockref->lock_count, \ + old.lock_count, \ + new.lock_count); \ if (likely(old.lock_count == prev.lock_count)) { \ SUCCESS; \ } \ - cpu_relax(); \ + arch_mutex_cpu_relax(); \ } \ } while (0) @@ -136,6 +153,7 @@ void lockref_mark_dead(struct lockref *lockref) assert_spin_locked(&lockref->lock); lockref->count = -128; } +EXPORT_SYMBOL(lockref_mark_dead); /** * lockref_get_not_dead - Increments count unless the ref is dead |