[PATCH 5.15 127/177] usb: typec: tcpm: fix tcpm unregister port but leave a pending timer

Greg Kroah-Hartman
2021-12-20T15:15:08Z

From: Xu Yang <xu.yang_2@nxp.com>

commit ca4d8344a72b91fb9d4c8bfbc22204b4c09c5d8f upstream.

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: <stable@vger.kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Link: https://lore.kernel.org/r/20211209101507.499096-1-xu.yang_2@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/typec/tcpm/tcpm.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -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_machin
{
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_ma
{
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_t
{
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_discove
{
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(str
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_po
{
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_po
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);