diff options
| -rw-r--r-- | sys/sys/buf_ring.h | 49 |
1 files changed, 16 insertions, 33 deletions
diff --git a/sys/sys/buf_ring.h b/sys/sys/buf_ring.h index b1ccaec..d36c607 100644 --- a/sys/sys/buf_ring.h +++ b/sys/sys/buf_ring.h @@ -64,8 +64,7 @@ struct buf_ring { static __inline int buf_ring_enqueue(struct buf_ring *br, void *buf) { - uint32_t prod_head, prod_next; - uint32_t cons_tail; + uint32_t prod_head, prod_next, cons_tail; #ifdef DEBUG_BUFRING int i; for (i = br->br_cons_head; i != br->br_prod_head; @@ -77,16 +76,20 @@ buf_ring_enqueue(struct buf_ring *br, void *buf) critical_enter(); do { prod_head = br->br_prod_head; + prod_next = (prod_head + 1) & br->br_prod_mask; cons_tail = br->br_cons_tail; - prod_next = (prod_head + 1) & br->br_prod_mask; - if (prod_next == cons_tail) { - br->br_drops++; - critical_exit(); - return (ENOBUFS); + rmb(); + if (prod_head == br->br_prod_head && + cons_tail == br->br_cons_tail) { + br->br_drops++; + critical_exit(); + return (ENOBUFS); + } + continue; } - } while (!atomic_cmpset_int(&br->br_prod_head, prod_head, prod_next)); + } while (!atomic_cmpset_acq_int(&br->br_prod_head, prod_head, prod_next)); #ifdef DEBUG_BUFRING if (br->br_ring[prod_head] != NULL) panic("dangling value in enqueue"); @@ -94,19 +97,13 @@ buf_ring_enqueue(struct buf_ring *br, void *buf) br->br_ring[prod_head] = buf; /* - * The full memory barrier also avoids that br_prod_tail store - * is reordered before the br_ring[prod_head] is full setup. - */ - mb(); - - /* * If there are other enqueues in progress * that preceeded us, we need to wait for them * to complete */ while (br->br_prod_tail != prod_head) cpu_spinwait(); - br->br_prod_tail = prod_next; + atomic_store_rel_int(&br->br_prod_tail, prod_next); critical_exit(); return (0); } @@ -119,37 +116,23 @@ static __inline void * buf_ring_dequeue_mc(struct buf_ring *br) { uint32_t cons_head, cons_next; - uint32_t prod_tail; void *buf; - int success; critical_enter(); do { cons_head = br->br_cons_head; - prod_tail = br->br_prod_tail; - cons_next = (cons_head + 1) & br->br_cons_mask; - - if (cons_head == prod_tail) { + + if (cons_head == br->br_prod_tail) { critical_exit(); return (NULL); } - - success = atomic_cmpset_int(&br->br_cons_head, cons_head, - cons_next); - } while (success == 0); + } while (!atomic_cmpset_acq_int(&br->br_cons_head, cons_head, cons_next)); buf = br->br_ring[cons_head]; #ifdef DEBUG_BUFRING br->br_ring[cons_head] = NULL; #endif - - /* - * The full memory barrier also avoids that br_ring[cons_read] - * load is reordered after br_cons_tail is set. - */ - mb(); - /* * If there are other dequeues in progress * that preceeded us, we need to wait for them @@ -158,7 +141,7 @@ buf_ring_dequeue_mc(struct buf_ring *br) while (br->br_cons_tail != cons_head) cpu_spinwait(); - br->br_cons_tail = cons_next; + atomic_store_rel_int(&br->br_cons_tail, cons_next); critical_exit(); return (buf); |
