[PATCH V4 net] net: mana: Fix MANA VF unload when host is unresponsive

souradeep chakrabarti
2023-07-03T08:50:07Z

From: Souradeep Chakrabarti <schakrabarti@linux.microsoft.com>

When unloading the MANA driver, mana_dealloc_queues() waits for the MANA
hardware to complete any inflight packets and set the pending send count
to zero. But if the hardware has failed, mana_dealloc_queues()
could wait forever.

Fix this by adding a timeout to the wait. Set the timeout to 120 seconds,
which is a somewhat arbitrary value that is more than long enough for
functional hardware to complete any sends.

Signed-off-by: Souradeep Chakrabarti <schakrabarti@linux.microsoft.com>
---
V3 -> V4:
* Fixed the commit message to describe the context.
* Removed the vf_unload_timeout, as it is not required.
---
drivers/net/ethernet/microsoft/mana/mana_en.c | 26 ++++++++++++++++---
1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index a499e460594b..d26f1da70411 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -2346,7 +2346,10 @@ static int mana_dealloc_queues(struct net_device *ndev)
{
struct mana_port_context *apc = netdev_priv(ndev);
struct gdma_dev *gd = apc->ac->gdma_dev;
+ unsigned long timeout;
struct mana_txq *txq;
+ struct sk_buff *skb;
+ struct mana_cq *cq;
int i, err;

if (apc->port_is_up)
@@ -2363,15 +2366,32 @@ static int mana_dealloc_queues(struct net_device *ndev)
* to false, but it doesn't matter since mana_start_xmit() drops any
* new packets due to apc->port_is_up being false.
*
- * Drain all the in-flight TX packets
+ * Drain all the in-flight TX packets.
+ * A timeout of 120 seconds for all the queues is used.
+ * This will break the while loop when h/w is not responding.
+ * This value of 120 has been decided here considering max
+ * number of queues.
*/
+
+ timeout = jiffies + 120 * HZ;
for (i = 0; i < apc->num_queues; i++) {
txq = &apc->tx_qp[i].txq;
-
- while (atomic_read(&txq->pending_sends) > 0)
+ while (atomic_read(&txq->pending_sends) > 0 &&
+ time_before(jiffies, timeout)) {
usleep_range(1000, 2000);
+ }
}

+ for (i = 0; i < apc->num_queues; i++) {
+ txq = &apc->tx_qp[i].txq;
+ cq = &apc->tx_qp[i].tx_cq;
+ while (atomic_read(&txq->pending_sends)) {
+ skb = skb_dequeue(&txq->pending_skbs);
+ mana_unmap_skb(skb, apc);
+ napi_consume_skb(skb, cq->budget);
+ atomic_sub(1, &txq->pending_sends);
+ }
+ }
/* We're 100% sure the queues can no longer be woken up, because
* we're sure now mana_poll_tx_cq() can't be running.
*/
--
2.34.1