ptr_ring: prevent queue load/store tearing (a07d29c6) · Commits · 戴 / test

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> Signed-off-by:

David S. Miller <davem@davemloft.net>

include/linux/ptr_ring.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}

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