From: "Michael S. Tsirkin" <[email protected]> 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 <[email protected]> > Suggested-by: Jason Wang <[email protected]> > Signed-off-by: Michael S. Tsirkin <[email protected]> > --- > > George, could you pls report whether this patch fixes > the issue for you? > > This seems to be needed in stable as well. I really need some testing feedback for this before I apply it and queue it up for -stable. George?
