From: "Michael S. Tsirkin" <m...@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.cher...@cavium.com> > Suggested-by: Jason Wang <jasow...@redhat.com> > Signed-off-by: Michael S. Tsirkin <m...@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.
