[PATCH V2] usb: typec: tcpm: fix tcpm unregister port but leave a pending timer
From: Xu Yang <xu.yang_2@nxp.com>
Date: 2021-12-09 10:16:23
Subsystem:
the rest, usb subsystem, usb typec class, usb typec port controller drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Heikki Krogerus, Badhri Jagan Sridharan
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: <redacted>
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
---
Changes in V2:
-Introduced a flag "port->registered" to avoid race.
---
drivers/usb/typec/tcpm/tcpm.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 6010b9901126..59d4fa2443f2 100644
--- 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_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);
--
2.25.1