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


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