Input: serio - fix potential deadlock when unbinding drivers
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>
diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
index 401ac6b..d59e18b 100644
--- a/drivers/input/mouse/psmouse-base.c
+++ b/drivers/input/mouse/psmouse-base.c
@@ -1450,24 +1450,10 @@
struct serio *serio = to_serio_port(dev);
struct psmouse_attribute *attr = to_psmouse_attr(devattr);
struct psmouse *psmouse;
- int retval;
-
- retval = serio_pin_driver(serio);
- if (retval)
- return retval;
-
- if (serio->drv != &psmouse_drv) {
- retval = -ENODEV;
- goto out;
- }
psmouse = serio_get_drvdata(serio);
- retval = attr->show(psmouse, attr->data, buf);
-
-out:
- serio_unpin_driver(serio);
- return retval;
+ return attr->show(psmouse, attr->data, buf);
}
ssize_t psmouse_attr_set_helper(struct device *dev, struct device_attribute *devattr,
@@ -1478,18 +1464,9 @@
struct psmouse *psmouse, *parent = NULL;
int retval;
- retval = serio_pin_driver(serio);
- if (retval)
- return retval;
-
- if (serio->drv != &psmouse_drv) {
- retval = -ENODEV;
- goto out_unpin;
- }
-
retval = mutex_lock_interruptible(&psmouse_mutex);
if (retval)
- goto out_unpin;
+ goto out;
psmouse = serio_get_drvdata(serio);
@@ -1519,8 +1496,7 @@
out_unlock:
mutex_unlock(&psmouse_mutex);
- out_unpin:
- serio_unpin_driver(serio);
+ out:
return retval;
}
@@ -1582,9 +1558,7 @@
}
mutex_unlock(&psmouse_mutex);
- serio_unpin_driver(serio);
serio_unregister_child_port(serio);
- serio_pin_driver_uninterruptible(serio);
mutex_lock(&psmouse_mutex);
if (serio->drv != &psmouse_drv) {