linux-stable.git/drivers/pinctrl/core.c, branch linux-3.12.y

pinctrl: Don't just pretend to protect pinctrl_maps, do it for real

2015-05-20T09:15:42+00:00

commit c5272a28566b00cce79127ad382406e0a8650690 upstream.

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 
Signed-off-by: Linus Walleij 
Signed-off-by: Jiri Slaby

pinctrl: Fix two deadlocks

2015-01-29T14:44:55+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: Jiri Slaby

pinctrl: protect pinctrl_list add

2014-02-20T19:08:02+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

Merge tag 'v3.11-rc7' into devel

2013-08-29T07:46:30+00:00

Merged in this to avoid conflicts with the big locking fixes
from upstream.

Signed-off-by: Linus Walleij 

Conflicts:
	drivers/pinctrl/pinctrl-sunxi.c

pinctrl: core: Add proper mutex lock in pinctrl_request_gpio

2013-08-28T11:13:05+00:00

This one is missed in commit 42fed7ba "pinctrl: move subsystem mutex to
pinctrl_dev struct".

I think this fixes the race between pin_free() and pin_request() calls.
It protects accessing the members of pctldev->desc.
(e.g. update desc->mux_usecount, desc->gpio_owner, desc->mux_owner, etc)
Current code grabs pctldev->mutex before calling pinmux_free_gpio(),
but did not grab the mutex while calling pinmux_request_gpio().

Signed-off-by: Axel Lin 
Signed-off-by: Linus Walleij

pinctrl: core: Remove unnecessary test for desc->name

2013-08-23T06:56:29+00:00

The implementation in pinctrl_register_one_pin() ensures pindesc->name is always
not NULL before insert the pindesc to radix tree.
If the desc return from pin_desc_get is not NULL, desc->name is always not NULL.

Signed-off-by: Axel Lin 
Signed-off-by: Linus Walleij

pinctrl: core: Hold pctldev->mutex mutex lock while traversing gpio_ranges list

2013-08-23T06:56:28+00:00

Hold pctldev->mutex mutex_lock when traverse the list.

Signed-off-by: Axel Lin 
Signed-off-by: Linus Walleij

pinctrl: core: Hold pinctrldev_list_mutex mutex while traversing pinctrldev_list

2013-08-23T06:56:27+00:00

This one is missed in commit 44d5f7bb "pinctrl: sink pinctrldev_list_mutex".

Signed-off-by: Axel Lin 
Signed-off-by: Linus Walleij

pinctrl: fix a memleak when freeing maps

2013-07-25T15:18:36+00:00

We forgot to free the node itself when free:ing a map.

Reported-by: xulinuxkernel 
Reviewed-by: Stephen Warren 
Signed-off-by: Linus Walleij

pinctrl: Remove duplicate code in pinctrl_pm_select_state functions

2013-07-22T23:23:27+00:00

There's no need to duplicate essentially the same functions. Let's
introduce static int pinctrl_pm_select_state() and make the other
related functions call that.

This allows us to add support later on for multiple active states,
and more optimized dynamic remuxing.

Note that we still need to export the various pinctrl_pm_select
functions as we want to keep struct pinctrl_state private to the
pinctrl code, and cannot replace those with inline functions.

Cc: Felipe Balbi 
Cc: Stephen Warren 
Signed-off-by: Grygorii Strashko 
Signed-off-by: Tony Lindgren 
Signed-off-by: Linus Walleij