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23 October 2021, 00:29:24 UTC
Revision a8ceb5dbfde1092b466936bca0ff3be127ecf38e authored by Michael S. Tsirkin on 05 December 2017, 19:29:37 UTC, committed by David S. Miller on 11 December 2017, 15:52:23 UTC 
ptr_ring: add barriers
 
Users of ptr_ring expect that it's safe to give the
data structure a pointer and have it be available
to consumers, but that actually requires an smb_wmb
or a stronger barrier.

In absence of such barriers and on architectures that reorder writes,
consumer might read an un=initialized value from an skb pointer stored
in the skb array.  This was observed causing crashes.

To fix, add memory barriers.  The barrier we use is a wmb, the
assumption being that producers do not need to read the value so we do
not need to order these reads.

Reported-by: George Cherian <george.cherian@cavium.com>
Suggested-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent f0f1d01
History
Tip revision: a8ceb5dbfde1092b466936bca0ff3be127ecf38e authored by Michael S. Tsirkin on 05 December 2017, 19:29:37 UTC
ptr_ring: add barriers
Tip revision: a8ceb5d
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