This is a note to let you know that I've just added the patch titled
pinctrl: Fix two deadlocks
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pinctrl-fix-two-deadlocks.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From db93facfb0ef542aa5d8079e47580b3e669a4d82 Mon Sep 17 00:00:00 2001
From: Jim Lin <jilin@xxxxxxxxxx>
Date: Thu, 8 Jan 2015 20:25:05 +0800
Subject: pinctrl: Fix two deadlocks
From: Jim Lin <jilin@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pinctrl/core.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -1801,14 +1801,15 @@ void pinctrl_unregister(struct pinctrl_d
if (pctldev == NULL)
return;
- mutex_lock(&pinctrldev_list_mutex);
mutex_lock(&pctldev->mutex);
-
pinctrl_remove_device_debugfs(pctldev);
+ mutex_unlock(&pctldev->mutex);
if (!IS_ERR(pctldev->p))
pinctrl_put(pctldev->p);
+ mutex_lock(&pinctrldev_list_mutex);
+ mutex_lock(&pctldev->mutex);
/* TODO: check that no pinmuxes are still active? */
list_del(&pctldev->node);
/* Destroy descriptor tree */
Patches currently in stable-queue which might be from jilin@xxxxxxxxxx are
queue-3.18/pinctrl-fix-two-deadlocks.patch
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