lkml.org 
[lkml]   [2017]   [Dec]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH] ptr_ring: add barriers
From
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.

\
 
 \ /
  Last update: 2017-12-11 16:54    [W:0.042 / U:0.160 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site