net/ncsi: Reset channel state in ncsi_start_dev()

When the NCSI driver is stopped with ncsi_stop_dev() the channel
monitors are stopped and the state set to "inactive". However the
channels are still configured and active from the perspective of the
network controller. We should suspend each active channel but in the
context of ncsi_stop_dev() the transmit queue has been or is about to be
stopped so we won't have time to do so.

Instead when ncsi_start_dev() is called if the NCSI topology has already
been probed then call ncsi_reset_dev() to suspend any channels that were
previously active. This resets the network controller to a known state,
provides an up to date view of channel link state, and makes sure that
mode flags such as NCSI_MODE_TX_ENABLE are properly reset.

In addition to ncsi_start_dev() use ncsi_reset_dev() in ncsi-netlink.c
to update the channel configuration more cleanly.

Signed-off-by: Samuel Mendoza-Jonas <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ncsi/internal.h

···
 #define NCSI_DEV_PROBED		1            /* Finalized NCSI topology    */
 #define NCSI_DEV_HWA		2            /* Enabled HW arbitration     */
 #define NCSI_DEV_RESHUFFLE	4
+#define NCSI_DEV_RESET		8            /* Reset state of NC          */
 	unsigned int        gma_flag;        /* OEM GMA flag               */
 	spinlock_t          lock;            /* Protect the NCSI device    */
 #if IS_ENABLED(CONFIG_IPV6)
···
 	list_for_each_entry_rcu(nc, &np->channels, node)
 
 /* Resources */
+int ncsi_reset_dev(struct ncsi_dev *nd);
 void ncsi_start_channel_monitor(struct ncsi_channel *nc);
 void ncsi_stop_channel_monitor(struct ncsi_channel *nc);
 struct ncsi_channel *ncsi_find_channel(struct ncsi_package *np,

net/ncsi/ncsi-manage.c

···
 		spin_lock_irqsave(&nc->lock, flags);
 		nc->state = NCSI_CHANNEL_INACTIVE;
 		spin_unlock_irqrestore(&nc->lock, flags);
-		ncsi_process_next_channel(ndp);
-
+		if (ndp->flags & NCSI_DEV_RESET)
+			ncsi_reset_dev(nd);
+		else
+			ncsi_process_next_channel(ndp);
 		break;
 	default:
 		netdev_warn(nd->dev, "Wrong NCSI state 0x%x in suspend\n",
···
 		netdev_dbg(ndp->ndev.dev, "NCSI: channel %u config done\n",
 			   nc->id);
 		spin_lock_irqsave(&nc->lock, flags);
+		nc->state = NCSI_CHANNEL_ACTIVE;
+
+		if (ndp->flags & NCSI_DEV_RESET) {
+			/* A reset event happened during config, start it now */
+			nc->reconfigure_needed = false;
+			spin_unlock_irqrestore(&nc->lock, flags);
+			ncsi_reset_dev(nd);
+			break;
+		}
+
 		if (nc->reconfigure_needed) {
 			/* This channel's configuration has been updated
 			 * part-way during the config state - start the
···
 			break;
 		}
 
-		nc->state = NCSI_CHANNEL_ACTIVE;
 		if (nc->modes[NCSI_MODE_LINK].data[2] & 0x1) {
 			hot_nc = nc;
 		} else {
···
 		return 0;
 	}
 
-	return ncsi_choose_active_channel(ndp);
+	return ncsi_reset_dev(nd);
 }
 EXPORT_SYMBOL_GPL(ncsi_start_dev);
 
···
 	int old_state;
 	unsigned long flags;
 
-	/* Stop the channel monitor and reset channel's state */
+	/* Stop the channel monitor on any active channels. Don't reset the
+	 * channel state so we know which were active when ncsi_start_dev()
+	 * is next called.
+	 */
 	NCSI_FOR_EACH_PACKAGE(ndp, np) {
 		NCSI_FOR_EACH_CHANNEL(np, nc) {
 			ncsi_stop_channel_monitor(nc);
···
 			spin_lock_irqsave(&nc->lock, flags);
 			chained = !list_empty(&nc->link);
 			old_state = nc->state;
-			nc->state = NCSI_CHANNEL_INACTIVE;
 			spin_unlock_irqrestore(&nc->lock, flags);
 
 			WARN_ON_ONCE(chained ||
···
 	ncsi_report_link(ndp, true);
 }
 EXPORT_SYMBOL_GPL(ncsi_stop_dev);
+
+int ncsi_reset_dev(struct ncsi_dev *nd)
+{
+	struct ncsi_dev_priv *ndp = TO_NCSI_DEV_PRIV(nd);
+	struct ncsi_channel *nc, *active, *tmp;
+	struct ncsi_package *np;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ndp->lock, flags);
+
+	if (!(ndp->flags & NCSI_DEV_RESET)) {
+		/* Haven't been called yet, check states */
+		switch (nd->state & ncsi_dev_state_major) {
+		case ncsi_dev_state_registered:
+		case ncsi_dev_state_probe:
+			/* Not even probed yet - do nothing */
+			spin_unlock_irqrestore(&ndp->lock, flags);
+			return 0;
+		case ncsi_dev_state_suspend:
+		case ncsi_dev_state_config:
+			/* Wait for the channel to finish its suspend/config
+			 * operation; once it finishes it will check for
+			 * NCSI_DEV_RESET and reset the state.
+			 */
+			ndp->flags |= NCSI_DEV_RESET;
+			spin_unlock_irqrestore(&ndp->lock, flags);
+			return 0;
+		}
+	} else {
+		switch (nd->state) {
+		case ncsi_dev_state_suspend_done:
+		case ncsi_dev_state_config_done:
+		case ncsi_dev_state_functional:
+			/* Ok */
+			break;
+		default:
+			/* Current reset operation happening */
+			spin_unlock_irqrestore(&ndp->lock, flags);
+			return 0;
+		}
+	}
+
+	if (!list_empty(&ndp->channel_queue)) {
+		/* Clear any channel queue we may have interrupted */
+		list_for_each_entry_safe(nc, tmp, &ndp->channel_queue, link)
+			list_del_init(&nc->link);
+	}
+	spin_unlock_irqrestore(&ndp->lock, flags);
+
+	active = NULL;
+	NCSI_FOR_EACH_PACKAGE(ndp, np) {
+		NCSI_FOR_EACH_CHANNEL(np, nc) {
+			spin_lock_irqsave(&nc->lock, flags);
+
+			if (nc->state == NCSI_CHANNEL_ACTIVE) {
+				active = nc;
+				nc->state = NCSI_CHANNEL_INVISIBLE;
+				spin_unlock_irqrestore(&nc->lock, flags);
+				ncsi_stop_channel_monitor(nc);
+				break;
+			}
+
+			spin_unlock_irqrestore(&nc->lock, flags);
+		}
+		if (active)
+			break;
+	}
+
+	if (!active) {
+		/* Done */
+		spin_lock_irqsave(&ndp->lock, flags);
+		ndp->flags &= ~NCSI_DEV_RESET;
+		spin_unlock_irqrestore(&ndp->lock, flags);
+		return ncsi_choose_active_channel(ndp);
+	}
+
+	spin_lock_irqsave(&ndp->lock, flags);
+	ndp->flags |= NCSI_DEV_RESET;
+	ndp->active_channel = active;
+	ndp->active_package = active->package;
+	spin_unlock_irqrestore(&ndp->lock, flags);
+
+	nd->state = ncsi_dev_state_suspend;
+	schedule_work(&ndp->work);
+	return 0;
+}
 
 void ncsi_unregister_dev(struct ncsi_dev *nd)
 {

net/ncsi/ncsi-netlink.c

···
 		    package_id, channel_id,
 		    channel_id == NCSI_RESERVED_CHANNEL ? " (any)" : "");
 
-	/* Bounce the NCSI channel to set changes */
-	ncsi_stop_dev(&ndp->ndev);
-	ncsi_start_dev(&ndp->ndev);
+	/* Update channel configuration */
+	if (!(ndp->flags & NCSI_DEV_RESET))
+		ncsi_reset_dev(&ndp->ndev);
 
 	return 0;
 }
···
 	spin_unlock_irqrestore(&ndp->lock, flags);
 	netdev_info(ndp->ndev.dev, "NCSI: Cleared preferred package/channel\n");
 
-	/* Bounce the NCSI channel to set changes */
-	ncsi_stop_dev(&ndp->ndev);
-	ncsi_start_dev(&ndp->ndev);
+	/* Update channel configuration */
+	if (!(ndp->flags & NCSI_DEV_RESET))
+		ncsi_reset_dev(&ndp->ndev);
 
 	return 0;
 }