Messages in this thread | | | Date | Mon, 11 Dec 2017 10:53:08 -0500 (EST) | Subject | Re: [PATCH] ptr_ring: add barriers | From | David Miller <> |
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From: "Michael S. Tsirkin" <mst@redhat.com> Date: Tue, 5 Dec 2017 21:29:37 +0200
> 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>
I'm asked for asking for testing feedback and did not get it in a reasonable amount of time.
So I'm applying this as-is, and queueing it up for -stable.
Thank you.
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