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authorMagnus Karlsson <magnus.karlsson@intel.com>2019-12-19 13:39:29 +0100
committerAlexei Starovoitov <ast@kernel.org>2019-12-20 16:00:09 -0800
commitc34787fcc90f0732ff00754057f11780007002e4 (patch)
treee2b70e5a4cebd0e99f5cbbd8dfd4d5df94cb8db6
parentf8509aa078de0842ec1817e8026e58620cd05d3b (diff)
downloadlinux-stericsson-c34787fcc90f0732ff00754057f11780007002e4.tar.gz
xsk: Remove unnecessary READ_ONCE of data
There are two unnecessary READ_ONCE of descriptor data. These are not needed since the data is written by the producer before it signals that the data is available by incrementing the producer pointer. As the access to this producer pointer is serialized and the consumer always reads the descriptor after it has read and synchronized with the producer counter, the write of the descriptor will have fully completed and it does not matter if the consumer has any read tearing. Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/1576759171-28550-11-git-send-email-magnus.karlsson@intel.com
-rw-r--r--net/xdp/xsk_queue.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 6d04a96dd092..4c049cacc693 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -183,7 +183,7 @@ static inline bool xskq_cons_read_addr(struct xsk_queue *q, u64 *addr,
while (q->cached_cons != q->cached_prod) {
u32 idx = q->cached_cons & q->ring_mask;
- *addr = READ_ONCE(ring->desc[idx]) & q->chunk_mask;
+ *addr = ring->desc[idx] & q->chunk_mask;
if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
if (xskq_cons_is_valid_unaligned(q, *addr,
@@ -308,7 +308,7 @@ static inline bool xskq_cons_read_desc(struct xsk_queue *q,
struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
u32 idx = q->cached_cons & q->ring_mask;
- *desc = READ_ONCE(ring->desc[idx]);
+ *desc = ring->desc[idx];
if (xskq_cons_is_valid_desc(q, desc, umem))
return true;