FAILED: patch "[PATCH] iavf: Fix deadlock occurrence during resetting VF interface" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0cc318d2e8408bc0ffb4662a0c3e5e57005ac6ff Mon Sep 17 00:00:00 2001
From: Jedrzej Jagielski <[email protected]>
Date: Tue, 7 Sep 2021 09:25:40 +0000
Subject: [PATCH] iavf: Fix deadlock occurrence during resetting VF interface

System hangs if close the interface is called from the kernel during the interface is in resetting state.
During resetting operation the link is closing but kernel didn't know it and it tried to close this interface again what sometimes led to deadlock.
Inform kernel about current state of interface
and turn off the flag IFF_UP when interface is closing until reset is finished.
Previously it was most likely to hang the system when kernel (network manager) tried to close the interface in the same time when interface was in resetting state because of deadlock.

index 336e6bf95e48..84680777ac12 100644
@@ -2254,6 +2254,7 @@ static void iavf_reset_task(struct work_struct *work)
 		   (adapter->state == __IAVF_RESETTING));
 
 	if (running) {
+		netdev->flags &= ~IFF_UP;
 		netif_carrier_off(netdev);
 		netif_tx_stop_all_queues(netdev);
 		adapter->link_up = false;

@@ -2365,7 +2366,7 @@ static void iavf_reset_task(struct work_struct *work)
 		 * to __IAVF_RUNNING
 		 */
 		iavf_up_complete(adapter);
-
+		netdev->flags |= IFF_UP;
 		iavf_irq_enable(adapter, true);
 	} else {
 		iavf_change_state(adapter, __IAVF_DOWN);

@@ -2378,8 +2379,10 @@ static void iavf_reset_task(struct work_struct *work)
 reset_err:
 	mutex_unlock(&adapter->client_lock);
 	mutex_unlock(&adapter->crit_lock);
-	if (running)
+	if (running) {
 		iavf_change_state(adapter, __IAVF_RUNNING);
+		netdev->flags |= IFF_UP;
+	}
 	dev_err(&adapter->pdev->dev, "failed to allocate resources during reinit\n");
 	iavf_close(netdev);
 }