linux-stable.git/drivers/pinctrl/core.c, branch v3.10.78

pinctrl: Fix two deadlocks

2015-01-30T01:40:55+00:00

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 
Signed-off-by: Linus Walleij 
Signed-off-by: Greg Kroah-Hartman

pinctrl: protect pinctrl_list add

2014-02-20T19:06:11+00:00

commit 7b320cb1ed2dbd2c5f2a778197baf76fd6bf545a upstream.

We have few fedora bug reports about list corruption on pinctrl,
for example:
https://bugzilla.redhat.com/show_bug.cgi?id=1051918

Most likely corruption happen due lack of protection of pinctrl_list
when adding new nodes to it. Patch corrects that.

Fixes: 42fed7ba44e ("pinctrl: move subsystem mutex to pinctrl_dev struct")
Signed-off-by: Stanislaw Gruszka 
Acked-by: Stephen Warren 
Signed-off-by: Linus Walleij 
Signed-off-by: Greg Kroah-Hartman

pinctrl: fix mutex deadlock in get_pinctrl_dev_from_of_node()

2013-04-30T11:02:04+00:00

This obvious bug was introduced by d755910b7 ("pinctrl: move subsystem
mutex to pinctrl_dev struct").

Signed-off-by: Daniel Mack 
Signed-off-by: Linus Walleij

pinctrl: move subsystem mutex to pinctrl_dev struct

2013-04-26T15:01:35+00:00

This mutex avoids deadlock in case of use of multiple pin
controllers. Before this modification, by using a global
mutex, deadlock appeared when, for example, a call to
pinctrl_pins_show() locked the pinctrl_mutex, called the
ops->pin_dbg_show of a particular pin controller. If this
pin controller needs I2C access to retrieve configuration
information and I2C driver is using pinctrl to drive its
pins, a call to pinctrl_select_state() try to lock again
pinctrl_mutex which leads to a deadlock.

Notice that the mutex grab from the two direction functions
was moved into pinctrl_gpio_direction().

For several cases, we can't replace pinctrl_mutex by
pctldev->mutex, because at this stage, pctldev is
not accessible :
	- pinctrl_get()/pinctrl_put()
	- pinctrl_register_maps()

So add respectively pinctrl_list_mutex and
pinctrl_maps_mutex in order to protect
pinctrl_list and pinctrl_maps list instead.

Reintroduce pinctrldev_list_mutex in
find_pinctrl_by_of_node(),
pinctrl_find_and_add_gpio_range()
pinctrl_request_gpio(), pinctrl_free_gpio(),
pinctrl_gpio_direction(), pinctrl_devices_show(),
pinctrl_register() and pinctrl_unregister() to
protect pinctrldev_list.

Changes v2->v3:
- Fix a missing EXPORT_SYMBOL_GPL() for pinctrl_select_state().

Changes v1->v2:
- pinctrl_select_state_locked() is removed, all lock mechanism
  is located inside pinctrl_select_state(). When parsing
  the state->setting list, take the per-pin-controller driver
  lock. (Patrice).
- Introduce pinctrldev_list_mutex to protect pinctrldev_list
  in all functions which parse or modify pictrldev_list.
  (Patrice).
- move find_pinctrl_by_of_node() from pinctrl/devicetree.c to
  pinctrl/core.c in order to protect pinctrldev_list.
  (Patrice).
- Sink mutex:es into some functions and remove some _locked
  variants down to where the lists are actually accessed to
  make things simpler. (Linus)
- Drop *all* mutexes completely from pinctrl_lookup_state()
  and pinctrl_select_state() - no relevant mutex was taken
  and it was unclear what this was protecting against. (Linus)

Reported by : Seraphin Bonnaffe 
Signed-off-by: Patrice Chotard 
Signed-off-by: Linus Walleij

pinctrl: simplify the re-enable old state code in pinctrl_select_state

2013-04-03T12:38:27+00:00

Instead of just enabling the settings that were disabled in the 1st
loop, it's simpler to recall pinctrl_select_state with the old state.

Signed-off-by: Richard Genoud 
Reviewed-by: Stephen Warren 
Signed-off-by: Linus Walleij

pinctrl: select_state: don't call pinctrl_free_setting on error

2013-04-03T12:36:43+00:00

As Stephen Warren pointed out, pinctrl_free_setting() was called instead
of pinmux_disable_setting() on error.
In this error code, we want to call pinmux_disable_setting() where
pinmux_enable_setting() was called.
And when pinconf_apply_setting() was called, we can't do much to undo
the pin muxing (the closest thing I can think about for "unmuxing" a pin
is muxing it as GPIO input).

Signed-off-by: Richard Genoud 
Reviewed-by: Stephen Warren 
Signed-off-by: Linus Walleij

pinctrl: pinctrl_select_state: set the old_state back on error

2013-04-03T12:27:31+00:00

In unapply_new_state, the old state is re-applied, but p->state is not
set back as it should.

Signed-off-by: Richard Genoud 
Reviewed-by: Stephen Warren 
Signed-off-by: Linus Walleij

pinctrl: remove superfluous optimization in pinctrl_select_state_locked

2013-04-03T12:22:39+00:00

As Stephen Warren suggested, checking first if the setting->node entry
is the first in the list or not is superfluous, as it is checked again
in the list_for_each_entry bellow.
So, remove it, the code will be simpler and lighter !

Signed-off-by: Richard Genoud 
Reviewed-by: Stephen Warren 
Signed-off-by: Linus Walleij

pinctrl: use dev_info instead of pr_info in pinctrl_select_state_locked

2013-04-03T12:20:37+00:00

And remove superfluous brackets.

Signed-off-by: Richard Genoud 
Reviewed-by: Stephen Warren 
Signed-off-by: Linus Walleij

pinctrl: core: add dependence of GPIOLIB

2013-04-03T11:48:33+00:00

In file included from drivers/pinctrl/core.c:30:0:
include/asm-generic/gpio.h: In function 'gpio_get_value_cansleep':
include/asm-generic/gpio.h:270:2: error: implicit declaration of
function '__gpio_get_value' [-Werror=implicit-function-declaration]
include/asm-generic/gpio.h: In function 'gpio_set_value_cansleep':
include/asm-generic/gpio.h:276:2: error: implicit declaration of
function '__gpio_set_value' [-Werror=implicit-function-declaration]
drivers/pinctrl/core.c: In function 'pinctrl_ready_for_gpio_range':
drivers/pinctrl/core.c:297:9: error: implicit declaration of function
'gpio_to_chip' [-Werror=implicit-function-declaration]
drivers/pinctrl/core.c:297:27: warning: initialization makes pointer
from integer without a cast [enabled by default]
drivers/pinctrl/core.c:304:45: error: dereferencing pointer to
incomplete type
drivers/pinctrl/core.c:305:26: error: dereferencing pointer to
incomplete type
drivers/pinctrl/core.c:305:39: error: dereferencing pointer to
incomplete type
cc1: some warnings being treated as errors
make[2]: *** [drivers/pinctrl/core.o] Error 1
make[1]: *** [drivers/pinctrl] Error 2
make[1]: *** Waiting for unfinished jobs....

It's caused by CONFIG_GPIOLIB isn't enabled for some platform. So
add the dependence on pinctrl_ready_for_gpio_range().

Signed-off-by: Haojian Zhuang 
Signed-off-by: Linus Walleij