net: arcnet: Fix RESET flag handling

The main arcnet interrupt handler calls arcnet_close() then
arcnet_open(), if the RESET status flag is encountered.

This is invalid:

1) In general, interrupt handlers should never call ->ndo_stop() and
->ndo_open() functions. They are usually full of blocking calls and
other methods that are expected to be called only from drivers
init and exit code paths.

2) arcnet_close() contains a del_timer_sync(). If the irq handler
interrupts the to-be-deleted timer, del_timer_sync() will just loop
forever.

3) arcnet_close() also calls tasklet_kill(), which has a warning if
called from irq context.

4) For device reset, the sequence "arcnet_close(); arcnet_open();" is
not complete. Some children arcnet drivers have special init/exit
code sequences, which then embed a call to arcnet_open() and
arcnet_close() accordingly. Check drivers/net/arcnet/com20020.c.

Run the device RESET sequence from a scheduled workqueue instead.

Signed-off-by: Ahmed S. Darwish <[e-mail]>
Signed-off-by: Sebastian Andrzej Siewior <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/arcnet/arc-rimi.c

···
 		dev->irq = 9;
 
 	if (arcrimi_probe(dev)) {
-		free_netdev(dev);
+		free_arcdev(dev);
 		return -EIO;
 	}
 
···
 	iounmap(lp->mem_start);
 	release_mem_region(dev->mem_start, dev->mem_end - dev->mem_start + 1);
 	free_irq(dev->irq, dev);
-	free_netdev(dev);
+	free_arcdev(dev);
 }
 
 #ifndef MODULE

drivers/net/arcnet/arcdevice.h

···
 
 	int excnak_pending;    /* We just got an excesive nak interrupt */
 
+	/* RESET flag handling */
+	int reset_in_progress;
+	struct work_struct reset_work;
+
 	struct {
 		uint16_t sequence;	/* sequence number (incs with each packet) */
 		__be16 aborted_seq;
···
 
 void arcnet_unregister_proto(struct ArcProto *proto);
 irqreturn_t arcnet_interrupt(int irq, void *dev_id);
+
 struct net_device *alloc_arcdev(const char *name);
+void free_arcdev(struct net_device *dev);
 
 int arcnet_open(struct net_device *dev);
 int arcnet_close(struct net_device *dev);

drivers/net/arcnet/arcnet.c

···
 	struct arcnet_local *lp = from_timer(lp, t, timer);
 	struct net_device *dev = lp->dev;
 
-	if (!netif_carrier_ok(dev)) {
+	spin_lock_irq(&lp->lock);
+
+	if (!lp->reset_in_progress && !netif_carrier_ok(dev)) {
 		netif_carrier_on(dev);
 		netdev_info(dev, "link up\n");
 	}
+
+	spin_unlock_irq(&lp->lock);
+}
+
+static void reset_device_work(struct work_struct *work)
+{
+	struct arcnet_local *lp;
+	struct net_device *dev;
+
+	lp = container_of(work, struct arcnet_local, reset_work);
+	dev = lp->dev;
+
+	/* Do not bring the network interface back up if an ifdown
+	 * was already done.
+	 */
+	if (!netif_running(dev) || !lp->reset_in_progress)
+		return;
+
+	rtnl_lock();
+
+	/* Do another check, in case of an ifdown that was triggered in
+	 * the small race window between the exit condition above and
+	 * acquiring RTNL.
+	 */
+	if (!netif_running(dev) || !lp->reset_in_progress)
+		goto out;
+
+	dev_close(dev);
+	dev_open(dev, NULL);
+
+out:
+	rtnl_unlock();
 }
 
 static void arcnet_reply_tasklet(unsigned long data)
···
 		lp->dev = dev;
 		spin_lock_init(&lp->lock);
 		timer_setup(&lp->timer, arcnet_timer, 0);
+		INIT_WORK(&lp->reset_work, reset_device_work);
 	}
 
 	return dev;
 }
 EXPORT_SYMBOL(alloc_arcdev);
+
+void free_arcdev(struct net_device *dev)
+{
+	struct arcnet_local *lp = netdev_priv(dev);
+
+	/* Do not cancel this at ->ndo_close(), as the workqueue itself
+	 * indirectly calls the ifdown path through dev_close().
+	 */
+	cancel_work_sync(&lp->reset_work);
+	free_netdev(dev);
+}
+EXPORT_SYMBOL(free_arcdev);
 
 /* Open/initialize the board.  This is called sometime after booting when
  * the 'ifconfig' program is run.
···
 
 	/* shut down the card */
 	lp->hw.close(dev);
+
+	/* reset counters */
+	lp->reset_in_progress = 0;
+
 	module_put(lp->hw.owner);
 	return 0;
 }
···
 
 	spin_lock_irqsave(&lp->lock, flags);
 
+	if (lp->reset_in_progress)
+		goto out;
+
 	/* RESET flag was enabled - if device is not running, we must
 	 * clear it right away (but nothing else).
 	 */
···
 		if (status & RESETflag) {
 			arc_printk(D_NORMAL, dev, "spurious reset (status=%Xh)\n",
 				   status);
-			arcnet_close(dev);
-			arcnet_open(dev);
+
+			lp->reset_in_progress = 1;
+			netif_stop_queue(dev);
+			netif_carrier_off(dev);
+			schedule_work(&lp->reset_work);
 
 			/* get out of the interrupt handler! */
-			break;
+			goto out;
 		}
 		/* RX is inhibited - we must have received something.
 		 * Prepare to receive into the next buffer.
···
 	udelay(1);
 	lp->hw.intmask(dev, lp->intmask);
 
+out:
 	spin_unlock_irqrestore(&lp->lock, flags);
 	return retval;
 }

drivers/net/arcnet/com20020-isa.c

···
 		dev->irq = 9;
 
 	if (com20020isa_probe(dev)) {
-		free_netdev(dev);
+		free_arcdev(dev);
 		return -EIO;
 	}
 
···
 	unregister_netdev(my_dev);
 	free_irq(my_dev->irq, my_dev);
 	release_region(my_dev->base_addr, ARCNET_TOTAL_SIZE);
-	free_netdev(my_dev);
+	free_arcdev(my_dev);
 }
 
 #ifndef MODULE

drivers/net/arcnet/com20020-pci.c

···
 
 		unregister_netdev(dev);
 		free_irq(dev->irq, dev);
-		free_netdev(dev);
+		free_arcdev(dev);
 	}
 }
 

drivers/net/arcnet/com20020_cs.c

···
 		dev = info->dev;
 		if (dev) {
 			dev_dbg(&link->dev, "kfree...\n");
-			free_netdev(dev);
+			free_arcdev(dev);
 		}
 		dev_dbg(&link->dev, "kfree2...\n");
 		kfree(info);

drivers/net/arcnet/com90io.c

···
 	err = com90io_probe(dev);
 
 	if (err) {
-		free_netdev(dev);
+		free_arcdev(dev);
 		return err;
 	}
 
···
 
 	free_irq(dev->irq, dev);
 	release_region(dev->base_addr, ARCNET_TOTAL_SIZE);
-	free_netdev(dev);
+	free_arcdev(dev);
 }
 
 module_init(com90io_init)

drivers/net/arcnet/com90xx.c

···
 err_release_mem:
 	release_mem_region(dev->mem_start, dev->mem_end - dev->mem_start + 1);
 err_free_dev:
-	free_netdev(dev);
+	free_arcdev(dev);
 	return -EIO;
 }
 
···
 		release_region(dev->base_addr, ARCNET_TOTAL_SIZE);
 		release_mem_region(dev->mem_start,
 				   dev->mem_end - dev->mem_start + 1);
-		free_netdev(dev);
+		free_arcdev(dev);
 	}
 }