linux-kernel - Re: [PATCH] thermal: int340x: processor

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Date:   Fri, 3 Mar 2023 20:36:23 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     rafael@...nel.org, rui.zhang@...el.com, daniel.lezcano@...aro.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Srinivas Pandruvada <srinivas.pandruvada@...el.com>,
        stable@...r.kernel.org
Subject: Re: [PATCH] thermal: int340x: processor_thermal: Fix deadlock

On Fri, Mar 3, 2023 at 5:19 PM Srinivas Pandruvada
<srinivas.pandruvada@...ux.intel.com> wrote:
>
> From: Srinivas Pandruvada <srinivas.pandruvada@...el.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@...el.com>
> Cc: stable@...r.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!