wifi: iwl3945: Add missing check for create_singlethread_workqueue

Add the check for the return value of the create_singlethread_workqueue
in order to avoid NULL pointer dereference.

Fixes: b481de9c ("[IWLWIFI]: add iwlwifi wireless drivers")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230208063032.42763-2-jiasheng@iscas.ac.cn

drivers/net/wireless/intel/iwlegacy/3945-mac.c

@@ -3372,10 +3372,12 @@ static DEVICE_ATTR(dump_errors, 0200, NULL, il3945_dump_error_log);
  *
  *****************************************************************************/
 
-static void
+static int
 il3945_setup_deferred_work(struct il_priv *il)
 {
 	il->workqueue = create_singlethread_workqueue(DRV_NAME);
+	if (!il->workqueue)
+		return -ENOMEM;
 
 	init_waitqueue_head(&il->wait_command_queue);
 
@@ -3392,6 +3394,8 @@ il3945_setup_deferred_work(struct il_priv *il)
 	timer_setup(&il->watchdog, il_bg_watchdog, 0);
 
 	tasklet_setup(&il->irq_tasklet, il3945_irq_tasklet);
+
+	return 0;
 }
 
 static void
@@ -3712,7 +3716,10 @@ il3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	}
 
 	il_set_rxon_channel(il, &il->bands[NL80211_BAND_2GHZ].channels[5]);
-	il3945_setup_deferred_work(il);
+	err = il3945_setup_deferred_work(il);
+	if (err)
+		goto out_remove_sysfs;
+
 	il3945_setup_handlers(il);
 	il_power_initialize(il);
 
@@ -3724,7 +3731,7 @@ il3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	err = il3945_setup_mac(il);
 	if (err)
-		goto out_remove_sysfs;
+		goto out_destroy_workqueue;
 
 	il_dbgfs_register(il, DRV_NAME);
 
@@ -3733,9 +3740,10 @@ il3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	return 0;
 
-out_remove_sysfs:
+out_destroy_workqueue:
 	destroy_workqueue(il->workqueue);
 	il->workqueue = NULL;
+out_remove_sysfs:
 	sysfs_remove_group(&pdev->dev.kobj, &il3945_attribute_group);
 out_release_irq:
 	free_irq(il->pci_dev->irq, il);