[patch 049/149] virtio_net: Make delayed refill more reliable
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From: Greg KH on 1 Jul 2010 14:30 2.6.32-stable review patch. If anyone has any objections, please let us know. ------------------ From: Herbert Xu <herbert(a)gondor.apana.org.au> commit 39d321577405e8e269fd238b278aaf2425fa788a upstream. I have seen RX stalls on a machine that experienced a suspected OOM. After the stall, the RX buffer is empty on the guest side and there are exactly 16 entries available on the host side. As the number of entries is less than that required by a maximal skb, the host cannot proceed. The guest did not have a refill job scheduled. My diagnosis is that an OOM had occured, with the delayed refill job scheduled. The job was able to allocate at least one skb, but not enough to overcome the minimum required by the host to proceed. As the refill job would only reschedule itself if it failed completely to allocate any skbs, this would lead to an RX stall. The following patch removes this stall possibility by always rescheduling the refill job until the ring is totally refilled. Testing has shown that the RX stall no longer occurs whereas previously it would occur within a day. Signed-off-by: Herbert Xu <herbert(a)gondor.apana.org.au> Acked-by: Rusty Russell <rusty(a)rustcorp.com.au> Signed-off-by: David S. Miller <davem(a)davemloft.net> Cc: Bruce Rogers <brogers(a)novell.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de> --- drivers/net/virtio_net.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -398,8 +398,7 @@ static void refill_work(struct work_stru vi = container_of(work, struct virtnet_info, refill.work); napi_disable(&vi->napi); - try_fill_recv(vi, GFP_KERNEL); - still_empty = (vi->num == 0); + still_empty = !try_fill_recv(vi, GFP_KERNEL); napi_enable(&vi->napi); /* In theory, this can happen: if we don't get any buffers in -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |