[3.5.y.z extended stable] Patch "tg3: Fix deadlock in tg3_change_mtu()" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    tg3: Fix deadlock in tg3_change_mtu()

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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>From 3c2746b50446bc2d4170e6f08a4706e5300fefad Mon Sep 17 00:00:00 2001
From: Nithin Sujir <nsujir at broadcom.com>
Date: Thu, 6 Feb 2014 14:13:05 -0800
Subject: tg3: Fix deadlock in tg3_change_mtu()

commit c6993dfd7db9b0c6b7ca7503a56fda9236a4710f upstream.

Quoting David Vrabel -
"5780 cards cannot have jumbo frames and TSO enabled together.  When
jumbo frames are enabled by setting the MTU, the TSO feature must be
cleared.  This is done indirectly by calling netdev_update_features()
which will call tg3_fix_features() to actually clear the flags.

netdev_update_features() will also trigger a new netlink message for the
feature change event which will result in a call to tg3_get_stats64()
which deadlocks on the tg3 lock."

tg3_set_mtu() does not need to be under the tg3 lock since converting
the flags to use set_bit(). Move it out to after tg3_netif_stop().

Reported-by: David Vrabel <david.vrabel at citrix.com>
Tested-by: David Vrabel <david.vrabel at citrix.com>
Signed-off-by: Michael Chan <mchan at broadcom.com>
Signed-off-by: Nithin Nayak Sujir <nsujir at broadcom.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/ethernet/broadcom/tg3.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index 3390b69..6dcd72a 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -12485,12 +12485,12 @@ static int tg3_change_mtu(struct net_device *dev, int new_mtu)

 	tg3_netif_stop(tp);

+	tg3_set_mtu(dev, tp, new_mtu);
+
 	tg3_full_lock(tp, 1);

 	tg3_halt(tp, RESET_KIND_SHUTDOWN, 1);

-	tg3_set_mtu(dev, tp, new_mtu);
-
 	/* Reset PHY, otherwise the read DMA engine will be in a mode that
 	 * breaks all requests to 256 bytes.
 	 */
--
1.9.0