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

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: ca9c54d2d6a5 ("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>

diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index a499e46..c2ad092 100644 (file)
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/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>
@@ -2345,9 +2346,12 @@ 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;
@@ -2363,15 +2367,40 @@ 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.
         */