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ptr_ring: support zero length ring 

Sometimes, we need zero length ring. But current code will crash since
we don't do any check before accessing the ring. This patch fixes this.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2016-06-30 14:45:31 +08:00 committed by David S. Miller
parent 8dc7243abb
commit 982fb490c2
1 changed files with 4 additions and 2 deletions
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6
include/linux/ptr_ring.h
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@ -102,7 +102,7 @@ static inline bool ptr_ring_full_bh(struct ptr_ring *r)
*/ */
static inline int __ptr_ring_produce(struct ptr_ring *r, void *ptr) static inline int __ptr_ring_produce(struct ptr_ring *r, void *ptr)
{ {
if (r->queue[r->producer]) if (unlikely(!r->size) || r->queue[r->producer])
return -ENOSPC; return -ENOSPC;
r->queue[r->producer++] = ptr; r->queue[r->producer++] = ptr;
@ -164,7 +164,9 @@ static inline int ptr_ring_produce_bh(struct ptr_ring *r, void *ptr)
*/ */
static inline void *__ptr_ring_peek(struct ptr_ring *r) static inline void *__ptr_ring_peek(struct ptr_ring *r)
{ {
return r->queue[r->consumer]; if (likely(r->size))
return r->queue[r->consumer];
return NULL;
} }
/* Note: callers invoking this in a loop must use a compiler barrier, /* Note: callers invoking this in a loop must use a compiler barrier,