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Input: serio - fix potential deadlock when unbinding drivers

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sysfs_remove_group() waits for sysfs attributes to be removed, therefore
we do not need to worry about driver-specific attributes being accessed
after driver has been detached from the device. In fact, attempts to take
serio->drv_mutex in attribute methods may lead to the following deadlock:

                                          sysfs_read_file()
                                            fill_read_buffer()
                                              sysfs_get_active_two()
                                                psmouse_attr_show_helper()
                                                  serio_pin_driver()
serio_disconnect_driver()
  mutex_lock(&serio->drv_mutex);
                                <-------->        mutex_lock(&serio_drv_mutex);
    psmouse_disconnect()
      sysfs_remove_group(... psmouse_attr_group);
        ....
        sysfs_deactivate();
          wait_for_completion();

Fix this by removing calls to serio_[un]pin_driver() and functions themselves
and using driver-private mutexes to serialize access to attribute's set()
methods that may change device state.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Eric W. Biederman 2010-01-05 17:56:02 -08:00 • committed by Dmitry Torokhov
parent abf2a117c6
commit 59b015133c
3 changed files with 28 additions and 82 deletions
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19
include/linux/serio.h
View file

@ -136,25 +136,6 @@ static inline void serio_continue_rx(struct serio *serio)
spin_unlock_irq(&serio->lock);
}
/*
* Use the following functions to pin serio's driver in process context
*/
static inline int serio_pin_driver(struct serio *serio)
{
return mutex_lock_interruptible(&serio->drv_mutex);
}
static inline void serio_pin_driver_uninterruptible(struct serio *serio)
{
mutex_lock(&serio->drv_mutex);
}
static inline void serio_unpin_driver(struct serio *serio)
{
mutex_unlock(&serio->drv_mutex);
}
#endif
/*