extcon: extcon-max14577: Fix potential work-queue cancellation race

The extcon IRQ schedules a work item. IRQ is requested using devm while
WQ is cancelld at remove(). This mixing of devm and manual unwinding has
potential case where the WQ has been emptied (.remove() was ran) but
devm unwinding of IRQ was not yet done. It is possible the IRQ is triggered
at this point scheduling new work item to the already flushed queue.

Use new devm_work_autocancel() to remove the remove() and to kill the bug.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Link: https://lore.kernel.org/r/ee8545f59ae3a93f0a70f640ecbd7e31cfadbcb9.1623146580.git.matti.vaittinen@fi.rohmeurope.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

diff --git a/drivers/extcon/extcon-max14577.c b/drivers/extcon/extcon-max14577.c
index ace5239..5476f48 100644 (file)
--- a/drivers/extcon/extcon-max14577.c
+++ b/drivers/extcon/extcon-max14577.c
@@ -6,6 +6,7 @@
 // Chanwoo Choi <cw00.choi@samsung.com>
 // Krzysztof Kozlowski <krzk@kernel.org>
 
+#include <linux/devm-helpers.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/i2c.h>
@@ -673,7 +674,10 @@ static int max14577_muic_probe(struct platform_device *pdev)
        platform_set_drvdata(pdev, info);
        mutex_init(&info->mutex);
 
-       INIT_WORK(&info->irq_work, max14577_muic_irq_work);
+       ret = devm_work_autocancel(&pdev->dev, &info->irq_work,
+                                  max14577_muic_irq_work);
+       if (ret)
+               return ret;
 
        switch (max14577->dev_type) {
        case MAXIM_DEVICE_TYPE_MAX77836:
@@ -766,15 +770,6 @@ static int max14577_muic_probe(struct platform_device *pdev)
        return ret;
 }
 
-static int max14577_muic_remove(struct platform_device *pdev)
-{
-       struct max14577_muic_info *info = platform_get_drvdata(pdev);
-
-       cancel_work_sync(&info->irq_work);
-
-       return 0;
-}
-
 static const struct platform_device_id max14577_muic_id[] = {
        { "max14577-muic", MAXIM_DEVICE_TYPE_MAX14577, },
        { "max77836-muic", MAXIM_DEVICE_TYPE_MAX77836, },
@@ -797,7 +792,6 @@ static struct platform_driver max14577_muic_driver = {
                .of_match_table = of_max14577_muic_dt_match,
        },
        .probe          = max14577_muic_probe,
-       .remove         = max14577_muic_remove,
        .id_table       = max14577_muic_id,
 };