From: Eric Dumazet <edumazet@google.com>
Date: Mon, 10 Dec 2012 12:32:03 +0000 (+0000)
Subject: net: fix a race in gro_cell_poll()
X-Git-Tag: omap-for-v3.8/fixes-for-merge-window-v4-signed~45^2~24
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f8e8f97c11d5ff3cc47d85b97c7c35e443dcf490;p=pandora-kernel.git

net: fix a race in gro_cell_poll()

Dmitry Kravkov reported packet drops for GRE packets since GRO support
was added.

There is a race in gro_cell_poll() because we call napi_complete()
without any synchronization with a concurrent gro_cells_receive()

Once bug was triggered, we queued packets but did not schedule NAPI
poll.

We can fix this issue using the spinlock protected the napi_skbs queue,
as we have to hold it to perform skb dequeue anyway.

As we open-code skb_dequeue(), we no longer need to mask IRQS, as both
producer and consumer run under BH context.

Bug added in commit c9e6bc644e (net: add gro_cells infrastructure)

Reported-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

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