[patch 127/149] ucc_geth: Fix empty TX queue processing

Greg KH
2010-07-01T18:30:54Z

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

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

From: Anton Vorontsov <avorontsov@ru.mvista.com>

commit 7583605b6d29f1f7f6fc505b883328089f3485ad upstream.

Following oops was seen with the ucc_geth driver:

Unable to handle kernel paging request for data at address 0x00000058
Faulting instruction address: 0xc024f2fc
Oops: Kernel access of bad area, sig: 11 [#1]
[...]
NIP [c024f2fc] skb_recycle_check+0x14/0x100
LR [e30aa0a4] ucc_geth_poll+0xd8/0x4e0 [ucc_geth_driver]
Call Trace:
[df857d50] [c000b03c] __ipipe_grab_irq+0x3c/0xa4 (unreliable)
[df857d60] [e30aa0a4] ucc_geth_poll+0xd8/0x4e0 [ucc_geth_driver]
[df857dd0] [c0258cf8] net_rx_action+0xf8/0x1b8
[df857e10] [c0032a38] __do_softirq+0xb8/0x13c
[df857e60] [c00065cc] do_softirq+0xa0/0xac
[...]

This is because ucc_geth_tx() tries to process an empty queue when
queues are logically stopped. Stopping the queues doesn't disable
polling, and since nowadays ucc_geth_tx() is actually called from
the polling routine, the oops above might pop up.

Fix this by removing 'netif_queue_stopped() == 0' check.

Reported-by: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Tested-by: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/net/ucc_geth.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ucc_geth.c
+++ b/drivers/net/ucc_geth.c
@@ -3273,7 +3273,7 @@ static int ucc_geth_tx(struct net_device
/* Handle the transmitted buffer and release */
/* the BD to be used with the current frame */

- if ((bd == ugeth->txBd[txQ]) && (netif_queue_stopped(dev) == 0))
+ if (bd == ugeth->txBd[txQ]) /* queue empty? */
break;

dev->stats.tx_packets++;