[PATCH net-next 08/12] ptr_ring: prevent queue load/store tearing
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2018-01-25 23:38:04
Also in:
lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
In theory compiler could tear queue loads or stores in two. It does not seem to be happening in practice but it seems easier to convert the cases where this would be a problem to READ/WRITE_ONCE than worry about it. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- include/linux/ptr_ring.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index 3a19ebd..1883d61 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h@@ -114,7 +114,7 @@ static inline int __ptr_ring_produce(struct ptr_ring *r, void *ptr) /* Pairs with smp_read_barrier_depends in __ptr_ring_consume. */ smp_wmb(); - r->queue[r->producer++] = ptr; + WRITE_ONCE(r->queue[r->producer++], ptr); if (unlikely(r->producer >= r->size)) r->producer = 0; return 0;
@@ -173,7 +173,7 @@ static inline int ptr_ring_produce_bh(struct ptr_ring *r, void *ptr) static inline void *__ptr_ring_peek(struct ptr_ring *r) { if (likely(r->size)) - return r->queue[r->consumer_head]; + return READ_ONCE(r->queue[r->consumer_head]); return NULL; }
--
MST