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 <ji...@nvidia.com>
---
drivers/pinctrl/core.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index e4f65510c87e..89dca77ca038 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -1801,14 +1801,15 @@ void pinctrl_unregister(struct pinctrl_dev *pctldev)
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 */
--
1.7.7
--
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