diff options
| -rw-r--r-- | sys/net/ifq.h | 2 | ||||
| -rw-r--r-- | sys/sys/buf_ring.h | 31 |
2 files changed, 32 insertions, 1 deletions
diff --git a/sys/net/ifq.h b/sys/net/ifq.h index 769d5a5..98a84aa 100644 --- a/sys/net/ifq.h +++ b/sys/net/ifq.h @@ -369,7 +369,7 @@ drbr_peek(struct ifnet *ifp, struct buf_ring *br) return (m); } #endif - return(buf_ring_peek(br)); + return(buf_ring_peek_clear_sc(br)); } static __inline void diff --git a/sys/sys/buf_ring.h b/sys/sys/buf_ring.h index 012aabf..6a6bfc4 100644 --- a/sys/sys/buf_ring.h +++ b/sys/sys/buf_ring.h @@ -268,6 +268,37 @@ buf_ring_peek(struct buf_ring *br) return (br->br_ring[br->br_cons_head]); } +static __inline void * +buf_ring_peek_clear_sc(struct buf_ring *br) +{ +#ifdef DEBUG_BUFRING + void *ret; + + if (!mtx_owned(br->br_lock)) + panic("lock not held on single consumer dequeue"); +#endif + /* + * I believe it is safe to not have a memory barrier + * here because we control cons and tail is worst case + * a lagging indicator so we worst case we might + * return NULL immediately after a buffer has been enqueued + */ + if (br->br_cons_head == br->br_prod_tail) + return (NULL); + +#ifdef DEBUG_BUFRING + /* + * Single consumer, i.e. cons_head will not move while we are + * running, so atomic_swap_ptr() is not necessary here. + */ + ret = br->br_ring[br->br_cons_head]; + br->br_ring[br->br_cons_head] = NULL; + return (ret); +#else + return (br->br_ring[br->br_cons_head]); +#endif +} + static __inline int buf_ring_full(struct buf_ring *br) { |
