| Message ID | 1420719905-15994-1-git-send-email-jilin@nvidia.com |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jan 8, 2015 at 1:25 PM, Jim Lin <jilin@nvidia.com> wrote: > 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@nvidia.com> Impressive and good catch. Applied to fixes and tagged for stable! Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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 */
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@nvidia.com> --- drivers/pinctrl/core.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-)