2012-03-23 10:29:46 -06:00
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2013-02-16 10:25:07 +01:00
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2012-03-23 10:29:46 -06:00
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pinctrl: Don't just pretend to protect pinctrl_maps, do it for real
Way back, when the world was a simpler place and there was no war, no
evil, and no kernel bugs, there was just a single pinctrl lock. That
was how the world was when (57291ce pinctrl: core device tree mapping
table parsing support) was written. In that case, there were
instances where the pinctrl mutex was already held when
pinctrl_register_map() was called, hence a "locked" parameter was
passed to the function to indicate that the mutex was already locked
(so we shouldn't lock it again).
A few years ago in (42fed7b pinctrl: move subsystem mutex to
pinctrl_dev struct), we switched to a separate pinctrl_maps_mutex.
...but (oops) we forgot to re-think about the whole "locked" parameter
for pinctrl_register_map(). Basically the "locked" parameter appears
to still refer to whether the bigger pinctrl_dev mutex is locked, but
we're using it to skip locks of our (now separate) pinctrl_maps_mutex.
That's kind of a bad thing(TM). Probably nobody noticed because most
of the calls to pinctrl_register_map happen at boot time and we've got
synchronous device probing. ...and even cases where we're
asynchronous don't end up actually hitting the race too often. ...but
after banging my head against the wall for a bug that reproduced 1 out
of 1000 reboots and lots of looking through kgdb, I finally noticed
this.
Anyway, we can now safely remove the "locked" parameter and go back to
a war-free, evil-free, and kernel-bug-free world.
Fixes: 42fed7ba44e4 ("pinctrl: move subsystem mutex to pinctrl_dev struct")
Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2015-05-01 09:01:27 -07:00
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2012-03-23 10:29:46 -06:00
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2012-11-06 16:03:35 +01:00
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2012-10-27 15:21:36 +05:30
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2015-06-18 14:42:45 +09:00
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2012-10-27 15:21:36 +05:30
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2012-03-23 10:29:46 -06:00
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2013-02-16 10:25:07 +01:00
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2012-03-23 10:29:46 -06:00
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2012-04-10 10:00:38 +02:00
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2012-03-23 10:29:46 -06:00
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2012-04-10 10:00:38 +02:00
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2012-03-23 10:29:46 -06:00
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pinctrl: move subsystem mutex to pinctrl_dev struct
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 <seraphin.bonnaffe@stericsson.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2013-04-11 11:01:27 +02:00
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2012-03-23 10:29:46 -06:00
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2013-01-11 21:22:36 +01:00
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2012-03-23 10:29:46 -06:00
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2014-01-30 18:57:20 +00:00
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2012-03-23 10:29:46 -06:00
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2016-06-16 16:27:41 +01:00
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2012-03-23 10:29:46 -06:00
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2016-06-16 16:27:41 +01:00
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2012-03-23 10:29:46 -06:00
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