linux-kernel - [PATCH v4 03/13] extcon: arizona: Fix various races on driver unbind

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Message-Id: <20210123121313.79530-4-hdegoede@redhat.com>
Date:   Sat, 23 Jan 2021 13:13:03 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Lee Jones <lee.jones@...aro.org>,
        Cezary Rojewski <cezary.rojewski@...el.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Liam Girdwood <liam.r.girdwood@...ux.intel.com>,
        Jie Yang <yang.jie@...ux.intel.com>,
        Mark Brown <broonie@...nel.org>
Cc:     Hans de Goede <hdegoede@...hat.com>, patches@...nsource.cirrus.com,
        linux-kernel@...r.kernel.org,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        alsa-devel@...a-project.org
Subject: [PATCH v4 03/13] extcon: arizona: Fix various races on driver unbind

We must free/disable all interrupts and cancel all pending works
before doing further cleanup.

Before this commit arizona_extcon_remove() was doing several
register writes to shut things down before disabling the IRQs
and it was cancelling only 1 of the 3 different works used.

Move all the register-writes shutting things down to after
the disabling of the IRQs and add the 2 missing
cancel_delayed_work_sync() calls.

This fixes various possible races on driver unbind. One of which
would always trigger on devices using the mic-clamp feature for
jack detection. The ARIZONA_MICD_CLAMP_MODE_MASK update was
done before disabling the IRQs, causing:
1. arizona_jackdet() to run
2. detect a jack being inserted (clamp disabled means jack inserted)
3. call arizona_start_mic() which:
3.1 Enables the MICVDD regulator
3.2 takes a pm_runtime_reference

And this was all happening after the ARIZONA_MICD_ENA bit clearing,
which would undo 3.1 and 3.2 because the ARIZONA_MICD_CLAMP_MODE_MASK
update was being done after the ARIZONA_MICD_ENA bit clearing.

So this means that arizona_extcon_remove() would exit with
1. MICVDD enabled and 2. The pm_runtime_reference being unbalanced.

MICVDD still being enabled caused the following oops when the
regulator is released by the devm framework:

[ 2850.745757] ------------[ cut here ]------------
[ 2850.745827] WARNING: CPU: 2 PID: 2098 at drivers/regulator/core.c:2123 _regulator_put.part.0+0x19f/0x1b0
[ 2850.745835] Modules linked in: extcon_arizona ...
...
[ 2850.746909] Call Trace:
[ 2850.746932]  regulator_put+0x2d/0x40
[ 2850.746946]  release_nodes+0x22a/0x260
[ 2850.746984]  __device_release_driver+0x190/0x240
[ 2850.747002]  driver_detach+0xd4/0x120
...
[ 2850.747337] ---[ end trace f455dfd7abd9781f ]---

Note this oops is just one of various theoretically possible races caused
by the wrong ordering inside arizona_extcon_remove(), this fixes the
ordering fixing all possible races, including the reported oops.

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
Acked-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
Signed-off-by: Hans de Goede <hdegoede@...hat.com>
---
 drivers/extcon/extcon-arizona.c | 40 +++++++++++++++++----------------
 1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/drivers/extcon/extcon-arizona.c b/drivers/extcon/extcon-arizona.c
index f7ef247de46a..76aacbac5869 100644
--- a/drivers/extcon/extcon-arizona.c
+++ b/drivers/extcon/extcon-arizona.c
@@ -1760,25 +1760,6 @@ static int arizona_extcon_remove(struct platform_device *pdev)
 	bool change;
 	int ret;
 
-	ret = regmap_update_bits_check(arizona->regmap, ARIZONA_MIC_DETECT_1,
-				       ARIZONA_MICD_ENA, 0,
-				       &change);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "Failed to disable micd on remove: %d\n",
-			ret);
-	} else if (change) {
-		regulator_disable(info->micvdd);
-		pm_runtime_put(info->dev);
-	}
-
-	gpiod_put(info->micd_pol_gpio);
-
-	pm_runtime_disable(&pdev->dev);
-
-	regmap_update_bits(arizona->regmap,
-			   ARIZONA_MICD_CLAMP_CONTROL,
-			   ARIZONA_MICD_CLAMP_MODE_MASK, 0);
-
 	if (info->micd_clamp) {
 		jack_irq_rise = ARIZONA_IRQ_MICD_CLAMP_RISE;
 		jack_irq_fall = ARIZONA_IRQ_MICD_CLAMP_FALL;
@@ -1794,10 +1775,31 @@ static int arizona_extcon_remove(struct platform_device *pdev)
 	arizona_free_irq(arizona, jack_irq_rise, info);
 	arizona_free_irq(arizona, jack_irq_fall, info);
 	cancel_delayed_work_sync(&info->hpdet_work);
+	cancel_delayed_work_sync(&info->micd_detect_work);
+	cancel_delayed_work_sync(&info->micd_timeout_work);
+
+	ret = regmap_update_bits_check(arizona->regmap, ARIZONA_MIC_DETECT_1,
+				       ARIZONA_MICD_ENA, 0,
+				       &change);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to disable micd on remove: %d\n",
+			ret);
+	} else if (change) {
+		regulator_disable(info->micvdd);
+		pm_runtime_put(info->dev);
+	}
+
+	regmap_update_bits(arizona->regmap,
+			   ARIZONA_MICD_CLAMP_CONTROL,
+			   ARIZONA_MICD_CLAMP_MODE_MASK, 0);
 	regmap_update_bits(arizona->regmap, ARIZONA_JACK_DETECT_ANALOGUE,
 			   ARIZONA_JD1_ENA, 0);
 	arizona_clk32k_disable(arizona);
 
+	gpiod_put(info->micd_pol_gpio);
+
+	pm_runtime_disable(&pdev->dev);
+
 	return 0;
 }
 
-- 
2.29.2