[PATCH] usb: typec: tcpm: fix tcpm unregister port but leave a pending timer

[Xu Yang <xu.yang_2@xxxxxxx>]

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 for
timeout even through tcpm port is removed. Once the hrtimer timeout, many
strange kernel dumps will 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: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Xu Yang <xu.yang_2@xxxxxxx>
---
 drivers/usb/typec/tcpm/tcpm.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 7f2f3ff1b391..91136d71640f 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -6295,7 +6295,8 @@ 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->wq)
+		kthread_queue_work(port->wq, &port->state_machine);
 	return HRTIMER_NORESTART;
 }
 
@@ -6303,7 +6304,8 @@ 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->wq)
+		kthread_queue_work(port->wq, &port->vdm_state_machine);
 	return HRTIMER_NORESTART;
 }
 
@@ -6311,7 +6313,8 @@ 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->wq)
+		kthread_queue_work(port->wq, &port->enable_frs);
 	return HRTIMER_NORESTART;
 }
 
@@ -6319,7 +6322,8 @@ 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->wq)
+		kthread_queue_work(port->wq, &port->send_discover_work);
 	return HRTIMER_NORESTART;
 }
 
@@ -6428,6 +6432,9 @@ void tcpm_unregister_port(struct tcpm_port *port)
 {
 	int i;
 
+	kthread_destroy_worker(port->wq);
+	port->wq = NULL;
+
 	hrtimer_cancel(&port->send_discover_timer);
 	hrtimer_cancel(&port->enable_frs_timer);
 	hrtimer_cancel(&port->vdm_state_machine_timer);
@@ -6439,7 +6446,6 @@ 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);
 
-- 
2.25.1