[PATCH] thermal: int340x: processor_thermal: Fix deadlock

[PATCH] thermal: int340x: processor_thermal: Fix deadlock

[Srinivas Pandruvada]

From: Srinivas Pandruvada <srinivas.pandruvada@intel.com>

When user space updates the trip point there is a deadlock, which results
in caller gets blocked forever.

Commit 05eeee2b51b4 ("thermal/core: Protect sysfs accesses to thermal
operations with thermal zone mutex"), added a mutex for tz->lock in the
function trip_point_temp_store(). Hence, trip set callback() can't
call any thermal zone API as they are protected with the same mutex lock.

The callback here calling thermal_zone_device_enable(), which will result
in deadlock.

Move the thermal_zone_device_enable() to proc_thermal_pci_probe() to
avoid this deadlock.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@intel.com>
Cc: stable@vger.kernel.org
---
The commit which caused this issue was added during v6.2 cycle.

 .../intel/int340x_thermal/processor_thermal_device_pci.c     | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c b/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c
index bf1b1cdfade4..acc11ad56975 100644
--- a/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c
+++ b/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c
@@ -194,7 +194,6 @@ static int sys_set_trip_temp(struct thermal_zone_device *tzd, int trip, int temp
 	proc_thermal_mmio_write(pci_info, PROC_THERMAL_MMIO_THRES_0, _temp);
 	proc_thermal_mmio_write(pci_info, PROC_THERMAL_MMIO_INT_ENABLE_0, 1);
 
-	thermal_zone_device_enable(tzd);
 	pci_info->stored_thres = temp;
 
 	return 0;
@@ -277,6 +276,10 @@ static int proc_thermal_pci_probe(struct pci_dev *pdev, const struct pci_device_
 		goto err_free_vectors;
 	}
 
+	ret = thermal_zone_device_enable(pci_info->tzone);
+	if (ret)
+		goto err_free_vectors;
+
 	return 0;
 
 err_free_vectors:
-- 
2.34.1

Re: [PATCH] thermal: int340x: processor_thermal: Fix deadlock

[Greg KH]

On Fri, Mar 03, 2023 at 08:19:09AM -0800, Srinivas Pandruvada wrote:
> From: Srinivas Pandruvada <srinivas.pandruvada@intel.com>
> 
> When user space updates the trip point there is a deadlock, which results
> in caller gets blocked forever.
> 
> Commit 05eeee2b51b4 ("thermal/core: Protect sysfs accesses to thermal
> operations with thermal zone mutex"), added a mutex for tz->lock in the
> function trip_point_temp_store(). Hence, trip set callback() can't
> call any thermal zone API as they are protected with the same mutex lock.
> 
> The callback here calling thermal_zone_device_enable(), which will result
> in deadlock.
> 
> Move the thermal_zone_device_enable() to proc_thermal_pci_probe() to
> avoid this deadlock.
> 
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@intel.com>
> Cc: stable@vger.kernel.org
> ---
> The commit which caused this issue was added during v6.2 cycle.

What commit exactly?  Always list that as a Fixes: tag if you know this.

thanks,

greg k-h

Re: [PATCH] thermal: int340x: processor_thermal: Fix deadlock

[Rafael J. Wysocki]

On Fri, Mar 3, 2023 at 7:52 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Fri, Mar 03, 2023 at 08:19:09AM -0800, Srinivas Pandruvada wrote:
> > From: Srinivas Pandruvada <srinivas.pandruvada@intel.com>
> >
> > When user space updates the trip point there is a deadlock, which results
> > in caller gets blocked forever.
> >
> > Commit 05eeee2b51b4 ("thermal/core: Protect sysfs accesses to thermal
> > operations with thermal zone mutex"), added a mutex for tz->lock in the
> > function trip_point_temp_store(). Hence, trip set callback() can't
> > call any thermal zone API as they are protected with the same mutex lock.
> >
> > The callback here calling thermal_zone_device_enable(), which will result
> > in deadlock.
> >
> > Move the thermal_zone_device_enable() to proc_thermal_pci_probe() to
> > avoid this deadlock.
> >
> > Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@intel.com>
> > Cc: stable@vger.kernel.org
> > ---
> > The commit which caused this issue was added during v6.2 cycle.
>
> What commit exactly?  Always list that as a Fixes: tag if you know this.

It's there in the changelog above.

I'll add a Fixes: tag to this one when applying it.

Cheers!

Re: [PATCH] thermal: int340x: processor_thermal: Fix deadlock

[Rafael J. Wysocki]

On Fri, Mar 3, 2023 at 5:19 PM Srinivas Pandruvada
<srinivas.pandruvada@linux.intel.com> wrote:
>
> From: Srinivas Pandruvada <srinivas.pandruvada@intel.com>
>
> When user space updates the trip point there is a deadlock, which results
> in caller gets blocked forever.
>
> Commit 05eeee2b51b4 ("thermal/core: Protect sysfs accesses to thermal
> operations with thermal zone mutex"), added a mutex for tz->lock in the
> function trip_point_temp_store(). Hence, trip set callback() can't
> call any thermal zone API as they are protected with the same mutex lock.
>
> The callback here calling thermal_zone_device_enable(), which will result
> in deadlock.
>
> Move the thermal_zone_device_enable() to proc_thermal_pci_probe() to
> avoid this deadlock.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@intel.com>
> Cc: stable@vger.kernel.org
> ---
> The commit which caused this issue was added during v6.2 cycle.
>
>  .../intel/int340x_thermal/processor_thermal_device_pci.c     | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c b/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c
> index bf1b1cdfade4..acc11ad56975 100644
> --- a/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c
> +++ b/drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci.c
> @@ -194,7 +194,6 @@ static int sys_set_trip_temp(struct thermal_zone_device *tzd, int trip, int temp
>         proc_thermal_mmio_write(pci_info, PROC_THERMAL_MMIO_THRES_0, _temp);
>         proc_thermal_mmio_write(pci_info, PROC_THERMAL_MMIO_INT_ENABLE_0, 1);
>
> -       thermal_zone_device_enable(tzd);
>         pci_info->stored_thres = temp;
>
>         return 0;
> @@ -277,6 +276,10 @@ static int proc_thermal_pci_probe(struct pci_dev *pdev, const struct pci_device_
>                 goto err_free_vectors;
>         }
>
> +       ret = thermal_zone_device_enable(pci_info->tzone);
> +       if (ret)
> +               goto err_free_vectors;
> +
>         return 0;
>
>  err_free_vectors:
> --

Now queued up for 6.3-rc with a Fixes: tag added, thanks!