[PATCH net-next 5/6] net/ncsi: Reset channel state in ncsi_start_dev()

[Samuel Mendoza-Jonas]

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 <sam at mendozajonas.com>
---
 net/ncsi/internal.h     |  2 ++
 net/ncsi/ncsi-manage.c  | 59 +++++++++++++++++++++++++++++++++++++----
 net/ncsi/ncsi-netlink.c | 10 +++----
 3 files changed, 60 insertions(+), 11 deletions(-)

diff --git a/net/ncsi/internal.h b/net/ncsi/internal.h
index 592e3cd40728..ed68ca677e41 100644
--- a/net/ncsi/internal.h
+++ b/net/ncsi/internal.h
@@ -279,6 +279,7 @@ struct ncsi_dev_priv {
 #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          */
 	spinlock_t          lock;            /* Protect the NCSI device    */
 #if IS_ENABLED(CONFIG_IPV6)
 	unsigned int        inet6_addr_num;  /* Number of IPv6 addresses   */
@@ -333,6 +334,7 @@ extern spinlock_t ncsi_dev_lock;
 	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,
diff --git a/net/ncsi/ncsi-manage.c b/net/ncsi/ncsi-manage.c
index 632caeea672f..af23e2cc6c1d 100644
--- a/net/ncsi/ncsi-manage.c
+++ b/net/ncsi/ncsi-manage.c
@@ -550,8 +550,10 @@ static void ncsi_suspend_channel(struct ncsi_dev_priv *ndp)
 		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",
@@ -1472,7 +1474,7 @@ int ncsi_start_dev(struct ncsi_dev *nd)
 		return 0;
 	}
 
-	return ncsi_choose_active_channel(nd);
+	return ncsi_reset_dev(nd);
 }
 EXPORT_SYMBOL_GPL(ncsi_start_dev);
 
@@ -1485,7 +1487,10 @@ void ncsi_stop_dev(struct ncsi_dev *nd)
 	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);
@@ -1493,7 +1498,6 @@ void ncsi_stop_dev(struct ncsi_dev *nd)
 			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 ||
@@ -1506,6 +1510,51 @@ void ncsi_stop_dev(struct ncsi_dev *nd)
 }
 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;
+	struct ncsi_package *np;
+	unsigned long flags;
+	bool enabled;
+	int state;
+
+	active = NULL;
+	NCSI_FOR_EACH_PACKAGE(ndp, np) {
+		NCSI_FOR_EACH_CHANNEL(np, nc) {
+			spin_lock_irqsave(&nc->lock, flags);
+			enabled = nc->monitor.enabled;
+			state = nc->state;
+			spin_unlock_irqrestore(&nc->lock, flags);
+
+			if (enabled)
+				ncsi_stop_channel_monitor(nc);
+			if (state == NCSI_CHANNEL_ACTIVE) {
+				active = nc;
+				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)
 {
 	struct ncsi_dev_priv *ndp = TO_NCSI_DEV_PRIV(nd);
diff --git a/net/ncsi/ncsi-netlink.c b/net/ncsi/ncsi-netlink.c
index 33314381b4f5..06bb8bc2c798 100644
--- a/net/ncsi/ncsi-netlink.c
+++ b/net/ncsi/ncsi-netlink.c
@@ -330,9 +330,8 @@ static int ncsi_set_interface_nl(struct sk_buff *msg, struct genl_info *info)
 		    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 */
+	ncsi_reset_dev(&ndp->ndev);
 
 	return 0;
 }
@@ -360,9 +359,8 @@ static int ncsi_clear_interface_nl(struct sk_buff *msg, struct genl_info *info)
 	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 */
+	ncsi_reset_dev(&ndp->ndev);
 
 	return 0;
 }
-- 
2.19.1