[PATCH AUTOSEL 6.3 34/44] media: cros-ec-cec: Don't exit early in .remove() callback

[PATCH AUTOSEL 6.3 34/44] media: cros-ec-cec: Don't exit early in .remove() callback

[Sasha Levin]

From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

[ Upstream commit 0ff7aee24e47beb4306ce050824b54147f2fabfa ]

Exiting early in remove without releasing all acquired resources yields
leaks. Note that e.g. memory allocated with devm_zalloc() is freed after
.remove() returns, even if the return code was negative.

While blocking_notifier_chain_unregister() won't fail and so the
change is somewhat cosmetic, platform driver's .remove callbacks are
about to be converted to return void. To prepare that, keep the error
message but don't return early.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/media/cec/platform/cros-ec/cros-ec-cec.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/media/cec/platform/cros-ec/cros-ec-cec.c b/drivers/media/cec/platform/cros-ec/cros-ec-cec.c
index 6ebedc71d67d4..960432230bbf1 100644
--- a/drivers/media/cec/platform/cros-ec/cros-ec-cec.c
+++ b/drivers/media/cec/platform/cros-ec/cros-ec-cec.c
@@ -332,14 +332,16 @@ static int cros_ec_cec_remove(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	int ret;
 
+	/*
+	 * blocking_notifier_chain_unregister() only fails if the notifier isn't
+	 * in the list. We know it was added to it by .probe(), so there should
+	 * be no need for error checking. Be cautious and still check.
+	 */
 	ret = blocking_notifier_chain_unregister(
 			&cros_ec_cec->cros_ec->event_notifier,
 			&cros_ec_cec->notifier);
-
-	if (ret) {
+	if (ret)
 		dev_err(dev, "failed to unregister notifier\n");
-		return ret;
-	}
 
 	cec_notifier_cec_adap_unregister(cros_ec_cec->notify,
 					 cros_ec_cec->adap);
-- 
2.39.2

Re: [PATCH AUTOSEL 6.3 34/44] media: cros-ec-cec: Don't exit early in .remove() callback

[Uwe Kleine-König]

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Hello,

On Sun, Apr 30, 2023 at 10:56:22PM -0400, Sasha Levin wrote:
> From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> 
> [ Upstream commit 0ff7aee24e47beb4306ce050824b54147f2fabfa ]
> 
> Exiting early in remove without releasing all acquired resources yields
> leaks. Note that e.g. memory allocated with devm_zalloc() is freed after
> .remove() returns, even if the return code was negative.
> 
> While blocking_notifier_chain_unregister() won't fail and so the
> change is somewhat cosmetic, platform driver's .remove callbacks are
> about to be converted to return void. To prepare that, keep the error
> message but don't return early.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> Signed-off-by: Sasha Levin <sashal@kernel.org>

While I'm positive this change doesn't break anything, it also doesn't
fix anything and is only cosmetic (+ preparing a later change).

Unless you need it as a dependency I'd say, don't backport it for
stable.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH AUTOSEL 6.3 34/44] media: cros-ec-cec: Don't exit early in .remove() callback

[Sasha Levin]

On Mon, May 01, 2023 at 05:26:32PM +0200, Uwe Kleine-König wrote:
>Hello,
>
>On Sun, Apr 30, 2023 at 10:56:22PM -0400, Sasha Levin wrote:
>> From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
>>
>> [ Upstream commit 0ff7aee24e47beb4306ce050824b54147f2fabfa ]
>>
>> Exiting early in remove without releasing all acquired resources yields
>> leaks. Note that e.g. memory allocated with devm_zalloc() is freed after
>> .remove() returns, even if the return code was negative.
>>
>> While blocking_notifier_chain_unregister() won't fail and so the
>> change is somewhat cosmetic, platform driver's .remove callbacks are
>> about to be converted to return void. To prepare that, keep the error
>> message but don't return early.
>>
>> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
>> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
>> Signed-off-by: Sasha Levin <sashal@kernel.org>
>
>While I'm positive this change doesn't break anything, it also doesn't
>fix anything and is only cosmetic (+ preparing a later change).
>
>Unless you need it as a dependency I'd say, don't backport it for
>stable.

Ack, dropped. Thanks!

-- 
Thanks,
Sasha