linux-kernel - [PATCH AUTOSEL 5.4 9/9] media: cros-ec-cec: Don't exit early in .remove() callback

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Message-Id: <20230501030611.3255082-9-sashal@kernel.org>
Date:   Sun, 30 Apr 2023 23:06:09 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Sasha Levin <sashal@...nel.org>, mchehab@...nel.org,
        bleung@...omium.org, linux-media@...r.kernel.org,
        chrome-platform@...ts.linux.dev
Subject: [PATCH AUTOSEL 5.4 9/9] media: cros-ec-cec: Don't exit early in .remove() callback

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

diff --git a/drivers/media/platform/cros-ec-cec/cros-ec-cec.c b/drivers/media/platform/cros-ec-cec/cros-ec-cec.c
index ae274a7aa3a94..dbdb57aea7457 100644
--- a/drivers/media/platform/cros-ec-cec/cros-ec-cec.c
+++ b/drivers/media/platform/cros-ec-cec/cros-ec-cec.c
@@ -324,14 +324,16 @@ 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);
 	cec_unregister_adapter(cros_ec_cec->adap);
-- 
2.39.2