thermal/drivers/broadcom: Fix race between removal and clock disable

During the probe, driver enables clocks necessary to access registers
(in get_temp()) and then registers thermal zone with managed-resources
(devm) interface.  Removal of device is not done in reversed order,
because:
1. Clock will be disabled in driver remove() callback - thermal zone is
   still registered and accessible to users,
2. devm interface will unregister thermal zone.

This leaves short window between (1) and (2) for accessing the
get_temp() callback with disabled clock.

Fix this by enabling clock also via devm-interface, so entire cleanup
path will be in proper, reversed order.

Fixes: 8454c8c09c77 ("thermal/drivers/bcm2835: Remove buggy call to thermal_of_zone_unregister")
Cc: stable@vger.kernel.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240709-thermal-probe-v1-1-241644e2b6e0@linaro.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

diff --git a/drivers/thermal/broadcom/bcm2835_thermal.c b/drivers/thermal/broadcom/bcm2835_thermal.c
index 5c1cebe07580113b1ba42a36e985fe6c1874820f..3b1030fc4fbfe0658afbb45b42fa4a0b40fc48e7 100644 (file)
--- a/drivers/thermal/broadcom/bcm2835_thermal.c
+++ b/drivers/thermal/broadcom/bcm2835_thermal.c
@@ -185,7 +185,7 @@ static int bcm2835_thermal_probe(struct platform_device *pdev)
                return err;
        }
 
-       data->clk = devm_clk_get(&pdev->dev, NULL);
+       data->clk = devm_clk_get_enabled(&pdev->dev, NULL);
        if (IS_ERR(data->clk)) {
                err = PTR_ERR(data->clk);
                if (err != -EPROBE_DEFER)
@@ -193,10 +193,6 @@ static int bcm2835_thermal_probe(struct platform_device *pdev)
                return err;
        }
 
-       err = clk_prepare_enable(data->clk);
-       if (err)
-               return err;
-
        rate = clk_get_rate(data->clk);
        if ((rate < 1920000) || (rate > 5000000))
                dev_warn(&pdev->dev,
@@ -211,7 +207,7 @@ static int bcm2835_thermal_probe(struct platform_device *pdev)
                dev_err(&pdev->dev,
                        "Failed to register the thermal device: %d\n",
                        err);
-               goto err_clk;
+               return err;
        }
 
        /*
@@ -236,7 +232,7 @@ static int bcm2835_thermal_probe(struct platform_device *pdev)
                        dev_err(&pdev->dev,
                                "Not able to read trip_temp: %d\n",
                                err);
-                       goto err_tz;
+                       return err;
                }
 
                /* set bandgap reference voltage and enable voltage regulator */
@@ -269,17 +265,11 @@ static int bcm2835_thermal_probe(struct platform_device *pdev)
         */
        err = thermal_add_hwmon_sysfs(tz);
        if (err)
-               goto err_tz;
+               return err;
 
        bcm2835_thermal_debugfs(pdev);
 
        return 0;
-err_tz:
-       devm_thermal_of_zone_unregister(&pdev->dev, tz);
-err_clk:
-       clk_disable_unprepare(data->clk);
-
-       return err;
 }
 
 static void bcm2835_thermal_remove(struct platform_device *pdev)
@@ -287,7 +277,6 @@ static void bcm2835_thermal_remove(struct platform_device *pdev)
        struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
 
        debugfs_remove_recursive(data->debugfsdir);
-       clk_disable_unprepare(data->clk);
 }
 
 static struct platform_driver bcm2835_thermal_driver = {