pinctrl: Fix two deadlocks
authorJim Lin <jilin@nvidia.com>
Thu, 8 Jan 2015 12:25:05 +0000 (20:25 +0800)
committerJiri Slaby <jslaby@suse.cz>
Thu, 29 Jan 2015 14:44:55 +0000 (15:44 +0100)
commit36b8f27a491d339ad4684c7560a398bcf6eda0d8
treea612c09b4741b41fdfc4fc82c80c262d4b354af3
parentc96807abeade37994e1105bbea59e79c3d699114
pinctrl: Fix two deadlocks

commit db93facfb0ef542aa5d8079e47580b3e669a4d82 upstream.

This patch is to fix two deadlock cases.
Deadlock 1:
CPU #1
 pinctrl_register-> pinctrl_get ->
 create_pinctrl
 (Holding lock pinctrl_maps_mutex)
 -> get_pinctrl_dev_from_devname
 (Trying to acquire lock pinctrldev_list_mutex)
CPU #0
 pinctrl_unregister
 (Holding lock pinctrldev_list_mutex)
 -> pinctrl_put ->> pinctrl_free ->
 pinctrl_dt_free_maps -> pinctrl_unregister_map
 (Trying to acquire lock pinctrl_maps_mutex)

Simply to say
CPU#1 is holding lock A and trying to acquire lock B,
CPU#0 is holding lock B and trying to acquire lock A.

Deadlock 2:
CPU #3
 pinctrl_register-> pinctrl_get ->
 create_pinctrl
 (Holding lock pinctrl_maps_mutex)
 -> get_pinctrl_dev_from_devname
 (Trying to acquire lock pinctrldev_list_mutex)
CPU #2
 pinctrl_unregister
 (Holding lock pctldev->mutex)
 -> pinctrl_put ->> pinctrl_free ->
 pinctrl_dt_free_maps -> pinctrl_unregister_map
 (Trying to acquire lock pinctrl_maps_mutex)
CPU #0
 tegra_gpio_request
 (Holding lock pinctrldev_list_mutex)
 -> pinctrl_get_device_gpio_range
 (Trying to acquire lock pctldev->mutex)

Simply to say
CPU#3 is holding lock A and trying to acquire lock D,
CPU#2 is holding lock B and trying to acquire lock A,
CPU#0 is holding lock D and trying to acquire lock B.

Signed-off-by: Jim Lin <jilin@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
drivers/pinctrl/core.c