Re: [PATCH net-next v2 5/7] ibmvnic: serialize access to work queue

On Tue, 12 Jan 2021 16:40:49 -0800 Sukadev Bhattiprolu wrote:

Saeed Mahameed [saeed@kernel.org] wrote:

quoted

On Tue, 2021-01-12 at 10:14 -0800, Sukadev Bhattiprolu wrote:  

<snip>

quoted

quoted

@@ -5467,7 +5472,15 @@ static int ibmvnic_remove(struct vio_dev *dev)
 		return -EBUSY;
 	}
 
+	/* If ibmvnic_reset() is scheduling a reset, wait for it to
+	 * finish. Then prevent it from scheduling any more resets
+	 * and have the reset functions ignore any resets that have
+	 * already been scheduled.
+	 */
+	spin_lock_irqsave(&adapter->remove_lock, flags);
 	adapter->state = VNIC_REMOVING;
+	spin_unlock_irqrestore(&adapter->remove_lock, flags);
+  

Why irqsave/restore variants ? are you expecting this spinlock to be
held in interruptcontext ?
  

quoted

 	spin_unlock_irqrestore(&adapter->state_lock, flags);  

Good question.

One of the callers of ibmvnic_reset() is the ->ndo_tx_timeout()
method which gets called from the watchdog timer.

watchdog is a normal timer, so it's gonna run in softirq, you don't
need to mask irqs.