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

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Date:   Fri,  3 Mar 2023 08:19:09 -0800
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     rafael@...nel.org, rui.zhang@...el.com, daniel.lezcano@...aro.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Srinivas Pandruvada <srinivas.pandruvada@...el.com>,
        stable@...r.kernel.org
Subject: [PATCH] thermal: int340x: processor_thermal: Fix deadlock

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:
-- 
2.34.1