diff options
| author | Mateusz Guzik <mjg@FreeBSD.org> | 2017-02-05 04:53:13 +0000 |
|---|---|---|
| committer | Mateusz Guzik <mjg@FreeBSD.org> | 2017-02-05 04:53:13 +0000 |
| commit | c84f3479856571c4f6505b23768324258cdf8a1c (patch) | |
| tree | f6d9162058d94ea4850dc1bd6a31ba7131bfc3d1 /sys/kern | |
| parent | 90836c3270786135dcae04c9eff80cdef9fe602c (diff) | |
| download | src-c84f3479856571c4f6505b23768324258cdf8a1c.tar.gz src-c84f3479856571c4f6505b23768324258cdf8a1c.zip | |
rwlock: switch to fcmpset
Discussed with: jhb
Tested by: pho
Notes
Notes:
svn path=/head/; revision=313270
Diffstat (limited to 'sys/kern')
| -rw-r--r-- | sys/kern/kern_rwlock.c | 19 |
1 files changed, 7 insertions, 12 deletions
diff --git a/sys/kern/kern_rwlock.c b/sys/kern/kern_rwlock.c index 99df700c8836..435caa2fa17d 100644 --- a/sys/kern/kern_rwlock.c +++ b/sys/kern/kern_rwlock.c @@ -440,7 +440,7 @@ __rw_rlock(volatile uintptr_t *c, const char *file, int line) * if the lock has been unlocked and write waiters * were present. */ - if (atomic_cmpset_acq_ptr(&rw->rw_lock, v, + if (atomic_fcmpset_acq_ptr(&rw->rw_lock, &v, v + RW_ONE_READER)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR4(KTR_LOCK, @@ -449,7 +449,6 @@ __rw_rlock(volatile uintptr_t *c, const char *file, int line) (void *)(v + RW_ONE_READER)); break; } - v = RW_READ_VALUE(rw); continue; } #ifdef KDTRACE_HOOKS @@ -675,7 +674,7 @@ _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line) * just drop one and return. */ if (RW_READERS(x) > 1) { - if (atomic_cmpset_rel_ptr(&rw->rw_lock, x, + if (atomic_fcmpset_rel_ptr(&rw->rw_lock, &x, x - RW_ONE_READER)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR4(KTR_LOCK, @@ -684,7 +683,6 @@ _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line) (void *)(x - RW_ONE_READER)); break; } - x = RW_READ_VALUE(rw); continue; } /* @@ -694,14 +692,13 @@ _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line) if (!(x & RW_LOCK_WAITERS)) { MPASS((x & ~RW_LOCK_WRITE_SPINNER) == RW_READERS_LOCK(1)); - if (atomic_cmpset_rel_ptr(&rw->rw_lock, x, + if (atomic_fcmpset_rel_ptr(&rw->rw_lock, &x, RW_UNLOCKED)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p last succeeded", __func__, rw); break; } - x = RW_READ_VALUE(rw); continue; } /* @@ -769,8 +766,8 @@ _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line) * read or write lock. */ void -__rw_wlock_hard(volatile uintptr_t *c, uintptr_t tid, const char *file, - int line) +__rw_wlock_hard(volatile uintptr_t *c, uintptr_t v, uintptr_t tid, + const char *file, int line) { struct rwlock *rw; struct turnstile *ts; @@ -779,7 +776,7 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t tid, const char *file, int spintries = 0; int i; #endif - uintptr_t v, x; + uintptr_t x; #ifdef LOCK_PROFILING uint64_t waittime = 0; int contested = 0; @@ -803,7 +800,6 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t tid, const char *file, lock_delay_arg_init(&lda, NULL); #endif rw = rwlock2rw(c); - v = RW_READ_VALUE(rw); if (__predict_false(lv_rw_wowner(v) == (struct thread *)tid)) { KASSERT(rw->lock_object.lo_flags & LO_RECURSABLE, @@ -825,9 +821,8 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t tid, const char *file, #endif for (;;) { if (v == RW_UNLOCKED) { - if (_rw_write_lock(rw, tid)) + if (_rw_write_lock_fetch(rw, &v, tid)) break; - v = RW_READ_VALUE(rw); continue; } #ifdef KDTRACE_HOOKS |