[PATCH for-2.6.35] tun: avoid BUG, dump packet on GSO errors

[PATCH for-2.6.35] tun: avoid BUG, dump packet on GSO errors

[Michael S. Tsirkin]

There are still some LRO cards that cause GSO errors in tun,
and BUG on this is an unfriendly way to tell the admin
to disable LRO.

Further, experience shows we might have more GSO bugs lurking.
See https://bugzilla.kernel.org/show_bug.cgi?id=16413
as a recent example.
dumping a packet will make it easier to figure it out.

Replace BUG with warning+dump+drop the packet to make
GSO errors in tun less critical and easier to debug.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Alex Unigovsky <unik@compot.ru>

---

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 6ad6fe7..6304259 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -736,8 +736,18 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
 				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 			else if (sinfo->gso_type & SKB_GSO_UDP)
 				gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
-			else
-				BUG();
+			else {
+				printk(KERN_ERR "tun: unexpected GSO type: "
+				       "0x%x, gso_size %d, hdr_len %d\n",
+				       sinfo->gso_type, gso.gso_size,
+				       gso.hdr_len);
+				print_hex_dump(KERN_ERR, "tun: ",
+					       DUMP_PREFIX_NONE,
+					       16, 1, skb->head,
+					       min((int)gso.hdr_len, 64), true);
+				WARN_ON_ONCE(1);
+				return -EINVAL;
+			}
 			if (sinfo->gso_type & SKB_GSO_TCP_ECN)
 				gso.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
 		} else

Re: [PATCH for-2.6.35] tun: avoid BUG, dump packet on GSO errors

[Herbert Xu]

Michael S. Tsirkin <mst@redhat.com> wrote:
> There are still some LRO cards that cause GSO errors in tun,
> and BUG on this is an unfriendly way to tell the admin
> to disable LRO.
> 
> Further, experience shows we might have more GSO bugs lurking.
> See https://bugzilla.kernel.org/show_bug.cgi?id=16413
> as a recent example.
> dumping a packet will make it easier to figure it out.
> 
> Replace BUG with warning+dump+drop the packet to make
> GSO errors in tun less critical and easier to debug.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Tested-by: Alex Unigovsky <unik@compot.ru>

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH for-2.6.35] tun: avoid BUG, dump packet on GSO errors

[David Miller]

From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Thu, 22 Jul 2010 21:05:12 +0800

> Michael S. Tsirkin <mst@redhat.com> wrote:
>> There are still some LRO cards that cause GSO errors in tun,
>> and BUG on this is an unfriendly way to tell the admin
>> to disable LRO.
>> 
>> Further, experience shows we might have more GSO bugs lurking.
>> See https://bugzilla.kernel.org/show_bug.cgi?id=16413
>> as a recent example.
>> dumping a packet will make it easier to figure it out.
>> 
>> Replace BUG with warning+dump+drop the packet to make
>> GSO errors in tun less critical and easier to debug.
>> 
>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>> Tested-by: Alex Unigovsky <unik@compot.ru>
> 
> Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

Applied, thanks everyone.