net: mana: Fix MANA VF unload when hardware is unresponsive

commit a7dfeda upstream.

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.

Cc: stable@vger.kernel.org
Fixes: ca9c54d ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)")
Signed-off-by: Souradeep Chakrabarti <schakrabarti@linux.microsoft.com>
Link: https://lore.kernel.org/r/1691576525-24271-1-git-send-email-schakrabarti@linux.microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/microsoft/mana/mana_en.c

@@ -8,6 +8,7 @@
 #include <linux/ethtool.h>
 #include <linux/filter.h>
 #include <linux/mm.h>
+#include <linux/pci.h>
 
 #include <net/checksum.h>
 #include <net/ip6_checksum.h>
@@ -2328,9 +2329,12 @@ int mana_attach(struct net_device *ndev)
 static int mana_dealloc_queues(struct net_device *ndev)
 {
 	struct mana_port_context *apc = netdev_priv(ndev);
+	unsigned long timeout = jiffies + 120 * HZ;
 	struct gdma_dev *gd = apc->ac->gdma_dev;
 	struct mana_txq *txq;
+	struct sk_buff *skb;
 	int i, err;
+	u32 tsleep;
 
 	if (apc->port_is_up)
 		return -EINVAL;
@@ -2346,15 +2350,40 @@ 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.
 	 */
+
 	for (i = 0; i < apc->num_queues; i++) {
 		txq = &apc->tx_qp[i].txq;
-
-		while (atomic_read(&txq->pending_sends) > 0)
-			usleep_range(1000, 2000);
+		tsleep = 1000;
+		while (atomic_read(&txq->pending_sends) > 0 &&
+		       time_before(jiffies, timeout)) {
+			usleep_range(tsleep, tsleep + 1000);
+			tsleep <<= 1;
+		}
+		if (atomic_read(&txq->pending_sends)) {
+			err = pcie_flr(to_pci_dev(gd->gdma_context->dev));
+			if (err) {
+				netdev_err(ndev, "flr failed %d with %d pkts pending in txq %u\n",
+					   err, atomic_read(&txq->pending_sends),
+					   txq->gdma_txq_id);
+			}
+			break;
+		}
 	}
 
+	for (i = 0; i < apc->num_queues; i++) {
+		txq = &apc->tx_qp[i].txq;
+		while ((skb = skb_dequeue(&txq->pending_skbs))) {
+			mana_unmap_skb(skb, apc);
+			dev_kfree_skb_any(skb);
+		}
+		atomic_set(&txq->pending_sends, 0);
+	}
 	/* 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.
 	 */