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FAILED: patch "[PATCH] usb: typec: tcpm: fix tcpm unregister port but leave a" failed to apply to 5.10-stable tree

PATCH [email protected] 1 participant 1 message Dec 20, 2021

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Stable branch USB USB Type-C class USB Type-C port controller drivers
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The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ca4d8344a72b91fb9d4c8bfbc22204b4c09c5d8f Mon Sep 17 00:00:00 2001
From: Xu Yang <[email protected]>
Date: Thu, 9 Dec 2021 18:15:07 +0800
Subject: [PATCH] usb: typec: tcpm: fix tcpm unregister port but leave a
pending timer

In current design, when the tcpm port is unregisterd, the kthread_worker will be destroyed in the last step. Inside the kthread_destroy_worker(), the worker will flush all the works and wait for them to end. However, if one of the works calls hrtimer_start(), this hrtimer will be pending until timeout even though tcpm port is removed. Once the hrtimer timeout, many strange kernel dumps appear.

Thus, we can first complete kthread_destroy_worker(), then cancel all the hrtimers. This will guarantee that no hrtimer is pending at the end.

Fixes 3ed8e1c2ac99 ("usb: typec: tcpm: Migrate workqueue to RT priority for processing events")
cc <[email protected]>
Reviewed-by Guenter Roeck <[email protected]>
Acked-by Heikki Krogerus <[email protected]>
Signed-off-by Xu Yang <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Greg Kroah-Hartman <[email protected]>
drivers/usb/typec/tcpm/tcpm.c +13 -5
index 6010b9901126..59d4fa2443f2 100644
@@ -324,6 +324,7 @@ struct tcpm_port {
 
 	bool attached;
 	bool connected;
+	bool registered;
 	bool pd_supported;
 	enum typec_port_type port_type;
 

@@ -6291,7 +6292,8 @@ static enum hrtimer_restart state_machine_timer_handler(struct hrtimer *timer)
 {
 	struct tcpm_port *port = container_of(timer, struct tcpm_port, state_machine_timer);
 
-	kthread_queue_work(port->wq, &port->state_machine);
+	if (port->registered)
+		kthread_queue_work(port->wq, &port->state_machine);
 	return HRTIMER_NORESTART;
 }
 

@@ -6299,7 +6301,8 @@ static enum hrtimer_restart vdm_state_machine_timer_handler(struct hrtimer *time
 {
 	struct tcpm_port *port = container_of(timer, struct tcpm_port, vdm_state_machine_timer);
 
-	kthread_queue_work(port->wq, &port->vdm_state_machine);
+	if (port->registered)
+		kthread_queue_work(port->wq, &port->vdm_state_machine);
 	return HRTIMER_NORESTART;
 }
 

@@ -6307,7 +6310,8 @@ static enum hrtimer_restart enable_frs_timer_handler(struct hrtimer *timer)
 {
 	struct tcpm_port *port = container_of(timer, struct tcpm_port, enable_frs_timer);
 
-	kthread_queue_work(port->wq, &port->enable_frs);
+	if (port->registered)
+		kthread_queue_work(port->wq, &port->enable_frs);
 	return HRTIMER_NORESTART;
 }
 

@@ -6315,7 +6319,8 @@ static enum hrtimer_restart send_discover_timer_handler(struct hrtimer *timer)
 {
 	struct tcpm_port *port = container_of(timer, struct tcpm_port, send_discover_timer);
 
-	kthread_queue_work(port->wq, &port->send_discover_work);
+	if (port->registered)
+		kthread_queue_work(port->wq, &port->send_discover_work);
 	return HRTIMER_NORESTART;
 }
 

@@ -6403,6 +6408,7 @@ struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc)
 	typec_port_register_altmodes(port->typec_port,
 				     &tcpm_altmode_ops, port,
 				     port->port_altmode, ALTMODE_DISCOVERY_MAX);
+	port->registered = true;
 
 	mutex_lock(&port->lock);
 	tcpm_init(port);

@@ -6424,6 +6430,9 @@ void tcpm_unregister_port(struct tcpm_port *port)
 {
 	int i;
 
+	port->registered = false;
+	kthread_destroy_worker(port->wq);
+
 	hrtimer_cancel(&port->send_discover_timer);
 	hrtimer_cancel(&port->enable_frs_timer);
 	hrtimer_cancel(&port->vdm_state_machine_timer);

@@ -6435,7 +6444,6 @@ void tcpm_unregister_port(struct tcpm_port *port)
 	typec_unregister_port(port->typec_port);
 	usb_role_switch_put(port->role_sw);
 	tcpm_debugfs_exit(port);
-	kthread_destroy_worker(port->wq);
 }
 EXPORT_SYMBOL_GPL(tcpm_unregister_port);