diff options
Diffstat (limited to 'src/mpmc_ptr_ring.h')
| -rw-r--r-- | src/mpmc_ptr_ring.h | 22 |
1 files changed, 10 insertions, 12 deletions
diff --git a/src/mpmc_ptr_ring.h b/src/mpmc_ptr_ring.h index a09e165..f68d709 100644 --- a/src/mpmc_ptr_ring.h +++ b/src/mpmc_ptr_ring.h @@ -78,7 +78,7 @@ static inline bool mpmc_ptr_ring_empty(struct mpmc_ptr_ring *r) static inline int mpmc_ptr_ring_produce(struct mpmc_ptr_ring *r, void *ptr) { - unsigned int p, c; + int p, c; unsigned int mask = r->mask; p = atomic_read(&r->producer_head); @@ -88,10 +88,10 @@ static inline int mpmc_ptr_ring_produce(struct mpmc_ptr_ring *r, void *ptr) c = atomic_read(&r->consumer_head); if ((p - c) < mask) { /* fast path */ - if (atomic_cmpxchg(&r->producer_head, p, p + 1) == p) + if (atomic_try_cmpxchg_relaxed(&r->producer_head, &p, p + 1)) break; } else { - unsigned int new_p; + int new_p; smp_rmb(); new_p = atomic_read(&r->producer_head); @@ -121,11 +121,11 @@ static inline int mpmc_ptr_ring_produce(struct mpmc_ptr_ring *r, void *ptr) static inline void *mpmc_ptr_ring_consume(struct mpmc_ptr_ring *r) { - unsigned int c, p, old_c; + int c, p; unsigned int mask = r->mask; void *element; - for (;;) { + do { c = atomic_read(&r->consumer_head); /* Fetch consumer_head first. */ @@ -139,13 +139,11 @@ static inline void *mpmc_ptr_ring_consume(struct mpmc_ptr_ring *r) element = READ_ONCE(r->queue[c & mask]); - /* TODO: Why? */ - smp_rmb(); - - old_c = atomic_cmpxchg(&r->consumer_head, c, c + 1); - if (old_c == c) - break; - } + /* + * Stores to consumer_head must be completed before we update + * the head, so we use *_release. + */ + } while (!atomic_try_cmpxchg_release(&r->consumer_head, &c, c + 1)); return element; } |