wireless: fix premature removal of hotplug devices due to down state

When a device is added that isn't up, status toggles can sometimes lead to a
DEV_EVENT_REMOVE event, which causes the device to be removed from an interface
or a bridge.
Fix this by toggling the dev->disabled status instead based on IFF_UP, and
adding a check to bridge/interface code to only permanently remove devices that
are actually gone.

Fixes: 516ab774cc16 ("system-linux: fix race condition on bringing up wireless devices")
Signed-off-by: Felix Fietkau <nbd@nbd.name>

5 files changed, 12 insertions, 11 deletions

diff --git a/bonding.c b/bonding.c
index 1f13148..532308c 100644
--- a/bonding.c
+++ b/bonding.c
@@ -303,7 +303,7 @@ bonding_port_cb(struct device_user *dep, enum device_event ev)
 		bonding_disable_port(bp, true);
 		break;
 	case DEV_EVENT_REMOVE:
-		if (dep->hotplug) {
+		if (dep->hotplug && !dev->sys_present) {
 			vlist_delete(&bdev->ports, &bp->node);
 			return;
 		}
diff --git a/bridge.c b/bridge.c
index 7a633ab..dd4d2c1 100644
--- a/bridge.c
+++ b/bridge.c
@@ -794,7 +794,7 @@ bridge_member_cb(struct device_user *dep, enum device_event ev)
 		bridge_disable_member(bm, true);
 		break;
 	case DEV_EVENT_REMOVE:
-		if (dep->hotplug) {
+		if (dep->hotplug && !dev->sys_present) {
 			vlist_delete(&bst->members, &bm->node);
 			return;
 		}
diff --git a/device.c b/device.c
index e26edbb..1370335 100644
--- a/device.c
+++ b/device.c
@@ -880,9 +880,9 @@ void device_cleanup(struct device *dev)
 	device_delete(dev);
 }
 
-static void __device_set_present(struct device *dev, bool state)
+static void __device_set_present(struct device *dev, bool state, bool force)
 {
-	if (dev->present == state)
+	if (dev->present == state && !force)
 		return;
 
 	dev->present = state;
@@ -897,7 +897,7 @@ device_refresh_present(struct device *dev)
 	if (dev->disabled || dev->deferred)
 		state = false;
 
-	__device_set_present(dev, state);
+	__device_set_present(dev, state, false);
 }
 
 void
@@ -937,7 +937,10 @@ void device_set_present(struct device *dev, bool state)
 
 	D(DEVICE, "%s '%s' %s present\n", dev->type->name, dev->ifname, state ? "is now" : "is no longer" );
 	dev->sys_present = state;
-	device_refresh_present(dev);
+	if (!state)
+		__device_set_present(dev, state, true);
+	else
+		device_refresh_present(dev);
 	if (!state)
 		safe_list_for_each(&dev->users, device_release_cb, NULL);
 }
diff --git a/interface.c b/interface.c
index b2c1230..03c781b 100644
--- a/interface.c
+++ b/interface.c
@@ -437,7 +437,7 @@ interface_main_dev_cb(struct device_user *dep, enum device_event ev)
 		break;
 	case DEV_EVENT_REMOVE:
 		interface_set_available(iface, false);
-		if (dep->dev && dep->dev->external)
+		if (dep->dev && dep->dev->external && !dep->dev->sys_present)
 			interface_set_main_dev(iface, NULL);
 		break;
 	case DEV_EVENT_UP:
diff --git a/system-linux.c b/system-linux.c
index 8efb020..21110c5 100644
--- a/system-linux.c
+++ b/system-linux.c
@@ -700,12 +700,10 @@ static void
 system_device_update_state(struct device *dev, unsigned int flags, unsigned int ifindex)
 {
 	if (dev->type == &simple_device_type) {
-		bool present = ifindex > 0;
-
 		if (dev->external)
-			present = present && (flags & IFF_UP);
+			device_set_disabled(dev, !(flags & IFF_UP));
 
-		device_set_present(dev, present);
+		device_set_present(dev, ifindex > 0);
 	}
 	device_set_link(dev, flags & IFF_LOWER_UP ? true : false);
 }