Messages in this thread | | | Subject | Re: [PATCH] ptr_ring: add barriers | From | George Cherian <> | Date | Tue, 12 Dec 2017 11:58:52 +0530 |
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Hi David,
On 12/11/2017 09:23 PM, David Miller wrote: > 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. > The tests have completed more than 48 hours without any failures. I won't interrupt the same and run for longer time. In case of any issue I will report the same. > So I'm applying this as-is, and queueing it up for -stable. > > Thank you.
Regards, -George >
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