[PATCH 5.15 556/917] ibmvnic: dont stop queue in xmit

Greg Kroah-Hartman
2021-11-15T23:51:20Z

From: Sukadev Bhattiprolu <sukadev@linux.ibm.com>

[ Upstream commit 8878e46fcfd46b19964bd90e13b25dd94cbfc9be ]

If adapter's resetting bit is on, discard the packet but don't stop the
transmit queue - instead leave that to the reset code. With this change,
it is possible that we may get several calls to ibmvnic_xmit() that simply
discard packets and return.

But if we stop the queue here, we might end up doing so just after
__ibmvnic_open() started the queues (during a hard/soft reset) and before
the ->resetting bit was cleared. If that happens, there will be no one to
restart queue and transmissions will be blocked indefinitely.

This can cause a TIMEOUT reset and with auto priority failover enabled,
an unnecessary FAILOVER reset to less favored backing device and then a
FAILOVER back to the most favored backing device. If we hit the window
repeatedly, we can get stuck in a loop of TIMEOUT, FAILOVER, FAILOVER
resets leaving the adapter unusable for extended periods of time.

Fixes: 7f5b030830fe ("ibmvnic: Free skb's in cases of failure in transmit")
Reported-by: Abdul Haleem <abdhalee@in.ibm.com>
Reported-by: Vaishnavi Bhat <vaish123@in.ibm.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
Reviewed-by: Dany Madden <drt@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/ibm/ibmvnic.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 6aa6ff89a7651..7438138c3766a 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -1724,8 +1724,6 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev)
ind_bufp = &tx_scrq->ind_buf;

if (test_bit(0, &adapter->resetting)) {
- if (!netif_subqueue_stopped(netdev, skb))
- netif_stop_subqueue(netdev, queue_num);
dev_kfree_skb_any(skb);

tx_send_failed++;
--
2.33.0