linux-kernel - [003/205] virtio_net: do not reschedule rx refill forever

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Message-Id: <20100730175133.867454088@clark.site>
Date:	Fri, 30 Jul 2010 10:50:20 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	"David S. Miller" <davem@...emloft.net>
Subject: [003/205] virtio_net: do not reschedule rx refill forever

2.6.34-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Michael S. Tsirkin <mst@...hat.com>

commit 1788f49548860fa1c861ee3454d47b466c877e43 upstream.

We currently fill all of RX ring, then add_buf
returns ENOSPC, which gets mis-detected as an out of
memory condition and causes us to reschedule the work,
and so on forever. Fix this by oom = err == -ENOMEM;

Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/net/virtio_net.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -417,7 +417,7 @@ static int add_recvbuf_mergeable(struct
 static bool try_fill_recv(struct virtnet_info *vi, gfp_t gfp)
 {
 	int err;
-	bool oom = false;
+	bool oom;
 
 	do {
 		if (vi->mergeable_rx_bufs)
@@ -427,10 +427,9 @@ static bool try_fill_recv(struct virtnet
 		else
 			err = add_recvbuf_small(vi, gfp);
 
-		if (err < 0) {
-			oom = true;
+		oom = err == -ENOMEM;
+		if (err < 0)
 			break;
-		}
 		++vi->num;
 	} while (err > 0);
 	if (unlikely(vi->num > vi->max))


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