Subject: [PATCH net] iavf: initialize waitqueues before starting watchdog_task

From: Michal Schmidt <[email-masked]>
Date: Thu, 19 Oct 2023 09:13:46 +0200

It is not safe to initialize the waitqueues after queueing the
watchdog_task. It will be using them.

The chance of this causing a real problem is very small, because
there will be some sleeping before any of the waitqueues get used.
I got a crash only after inserting an artificial sleep in iavf_probe.

Queue the watchdog_task as the last step in iavf_probe. Add a comment to
prevent repeating the mistake.

Fixes: fe2647ab0c99 ("i40evf: prevent VF close returning before state transitions to DOWN")
Signed-off-by: Michal Schmidt <[email-masked]>
---
 drivers/net/ethernet/intel/iavf/iavf_main.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
index 6a2e6d64bc3a..5b5c0525aa13 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_main.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
@@ -4982,8 +4982,6 @@ static int iavf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	INIT_WORK(&adapter->finish_config, iavf_finish_config);
 	INIT_DELAYED_WORK(&adapter->watchdog_task, iavf_watchdog_task);
 	INIT_DELAYED_WORK(&adapter->client_task, iavf_client_task);
-	queue_delayed_work(adapter->wq, &adapter->watchdog_task,
-			   msecs_to_jiffies(5 * (pdev->devfn & 0x07)));
 
 	/* Setup the wait queue for indicating transition to down status */
 	init_waitqueue_head(&adapter->down_waitqueue);
@@ -4994,6 +4992,9 @@ static int iavf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	/* Setup the wait queue for indicating virtchannel events */
 	init_waitqueue_head(&adapter->vc_waitqueue);
 
+	queue_delayed_work(adapter->wq, &adapter->watchdog_task,
+			   msecs_to_jiffies(5 * (pdev->devfn & 0x07)));
+	/* Initialization goes on in the work. Do not add more of it below. */
 	return 0;
 
 err_ioremap:
-- 
2.41.0