[PATCH net-next v11 3/7] netconsole: add STATE_DEACTIVATED to track targets disabled by low level

[Andre Carvalho <asantostc@gmail.com>]

From: Breno Leitao <leitao@debian.org>

When the low level interface brings a netconsole target down, record this
using a new STATE_DEACTIVATED state. This allows netconsole to distinguish
between targets explicitly disabled by users and those deactivated due to
interface state changes.

It also enables automatic recovery and re-enabling of targets if the
underlying low-level interfaces come back online.

From a code perspective, anything that is not STATE_ENABLED is disabled.

Devices (de)enslaving are marked STATE_DISABLED to prevent automatically
resuming as enslaved interfaces cannot have netconsole enabled.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Andre Carvalho <asantostc@gmail.com>
---
 drivers/net/netconsole.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index b21ecea60d52..7a1e5559fc0d 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -122,6 +122,7 @@ enum sysdata_feature {
 enum target_state {
 	STATE_DISABLED,
 	STATE_ENABLED,
+	STATE_DEACTIVATED,
 };
 
 /**
@@ -580,6 +581,14 @@ static ssize_t enabled_store(struct config_item *item,
 	if (ret)
 		goto out_unlock;
 
+	/* When the user explicitly enables or disables a target that is
+	 * currently deactivated, reset its state to disabled. The DEACTIVATED
+	 * state only tracks interface-driven deactivation and should _not_
+	 * persist when the user manually changes the target's enabled state.
+	 */
+	if (nt->state == STATE_DEACTIVATED)
+		nt->state = STATE_DISABLED;
+
 	ret = -EINVAL;
 	current_enabled = nt->state == STATE_ENABLED;
 	if (enabled == current_enabled) {
@@ -1445,10 +1454,19 @@ static int netconsole_netdev_event(struct notifier_block *this,
 				break;
 			case NETDEV_RELEASE:
 			case NETDEV_JOIN:
-			case NETDEV_UNREGISTER:
+				/* transition target to DISABLED instead of
+				 * DEACTIVATED when (de)enslaving devices as
+				 * their targets should not be automatically
+				 * resumed when the interface is brought up.
+				 */
 				nt->state = STATE_DISABLED;
 				list_move(&nt->list, &target_cleanup_list);
 				stopped = true;
+				break;
+			case NETDEV_UNREGISTER:
+				nt->state = STATE_DEACTIVATED;
+				list_move(&nt->list, &target_cleanup_list);
+				stopped = true;
 			}
 		}
 		netconsole_target_put(nt);

-- 
2.52.0