This is a note to let you know that I've just added the patch titled
af_packet: remove BUG statement in tpacket_destruct_skb
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
af_packet-remove-bug-statement-in-tpacket_destruct_skb.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 20897991d4bef87c60d31987ee913bd9499da04d Mon Sep 17 00:00:00 2001
From: "[email protected]" <[email protected]>
Date: Fri, 10 Aug 2012 22:48:54 +0000
Subject: af_packet: remove BUG statement in tpacket_destruct_skb
From: "[email protected]" <[email protected]>
[ Upstream commit 7f5c3e3a80e6654cf48dfba7cf94f88c6b505467 ]
Here's a quote of the comment about the BUG macro from asm-generic/bug.h:
Don't use BUG() or BUG_ON() unless there's really no way out; one
example might be detecting data structure corruption in the middle
of an operation that can't be backed out of. If the (sub)system
can somehow continue operating, perhaps with reduced functionality,
it's probably not BUG-worthy.
If you're tempted to BUG(), think again: is completely giving up
really the *only* solution? There are usually better options, where
users don't need to reboot ASAP and can mostly shut down cleanly.
In our case, the status flag of a ring buffer slot is managed from both sides,
the kernel space and the user space. This means that even though the kernel
side might work as expected, the user space screws up and changes this flag
right between the send(2) is triggered when the flag is changed to
TP_STATUS_SENDING and a given skb is destructed after some time. Then, this
will hit the BUG macro. As David suggested, the best solution is to simply
remove this statement since it cannot be used for kernel side internal
consistency checks. I've tested it and the system still behaves /stable/ in
this case, so in accordance with the above comment, we should rather remove it.
Signed-off-by: Daniel Borkmann <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
net/packet/af_packet.c | 1 -
1 file changed, 1 deletion(-)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1943,7 +1943,6 @@ static void tpacket_destruct_skb(struct
if (likely(po->tx_ring.pg_vec)) {
ph = skb_shinfo(skb)->destructor_arg;
- BUG_ON(__packet_get_status(po, ph) != TP_STATUS_SENDING);
BUG_ON(atomic_read(&po->tx_ring.pending) == 0);
atomic_dec(&po->tx_ring.pending);
__packet_set_status(po, ph, TP_STATUS_AVAILABLE);
Patches currently in stable-queue which might be from [email protected]
are
queue-3.4/af_packet-remove-bug-statement-in-tpacket_destruct_skb.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
