linux-kernel - Re: [PATCH 4.14 04/33] Input: stmfts - fix reference leak in stmfts_input

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Message-ID: <Yo5vmwfaJKhg9fzF@google.com>
Date:   Wed, 25 May 2022 11:04:11 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Pavel Machek <pavel@...x.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Zheng Yongjun <zhengyongjun3@...wei.com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.14 04/33] Input: stmfts - fix reference leak in
 stmfts_input_open

On Wed, May 25, 2022 at 12:52:48PM +0200, Pavel Machek wrote:
> Hi!
> 
> > From: Zheng Yongjun <zhengyongjun3@...wei.com>
> > 
> > [ Upstream commit 26623eea0da3476446909af96c980768df07bbd9 ]
> > 
> > pm_runtime_get_sync() will increment pm usage counter even it
> > failed. Forgetting to call pm_runtime_put_noidle will result
> > in reference leak in stmfts_input_open, so we should fix it.
> 
> This is wrong, AFAICT.

Yes, I think you are right. How about below?

Thanks.

-- 
Dmitry


Input: stmfts - do not leave device disabled in stmfts_input_open

From: Dmitry Torokhov <dmitry.torokhov@...il.com>

The commit 26623eea0da3 attempted to deal with potential leak of runtime
PM counter when opening the touchscreen device, however it ended up
erroneously dropping the counter in the case of successfully enabling the
device.

Let's address this by using pm_runtime_resume_and_get() and then executing
pm_runtime_put_sync() only when we fail to send "sense on" command to the
device.

Fixes: 26623eea0da3 ("Input: stmfts - fix reference leak in stmfts_input_open")
Reported-by: Pavel Machek <pavel@...x.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
 drivers/input/touchscreen/stmfts.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/input/touchscreen/stmfts.c b/drivers/input/touchscreen/stmfts.c
index 72e0b767e1ba..c175d44c52f3 100644
--- a/drivers/input/touchscreen/stmfts.c
+++ b/drivers/input/touchscreen/stmfts.c
@@ -337,13 +337,15 @@ static int stmfts_input_open(struct input_dev *dev)
 	struct stmfts_data *sdata = input_get_drvdata(dev);
 	int err;
 
-	err = pm_runtime_get_sync(&sdata->client->dev);
-	if (err < 0)
-		goto out;
+	err = pm_runtime_resume_and_get(&sdata->client->dev);
+	if (err)
+		return err;
 
 	err = i2c_smbus_write_byte(sdata->client, STMFTS_MS_MT_SENSE_ON);
-	if (err)
-		goto out;
+	if (err) {
+		pm_runtime_put_sync(&sdata->client->dev);
+		return err;
+	}
 
 	mutex_lock(&sdata->mutex);
 	sdata->running = true;
@@ -366,9 +368,7 @@ static int stmfts_input_open(struct input_dev *dev)
 				 "failed to enable touchkey\n");
 	}
 
-out:
-	pm_runtime_put_noidle(&sdata->client->dev);
-	return err;
+	return 0;
 }
 
 static void stmfts_input_close(struct input_dev *dev)