Re: [PATCH] usb: typec: tcpci: Don't skip cleanup in .remove() on error

From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Guenter Roeck <linux@roeck-us.net>, Jun Li <jun.li@nxp.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org, kernel@pengutronix.de
Subject: Re: [PATCH] usb: typec: tcpci: Don't skip cleanup in .remove() on error
Date: Mon, 2 May 2022 15:27:17 +0300	[thread overview]
Message-ID: <Ym/OJRdZxmqDK8/3@kuha.fi.intel.com> (raw)
In-Reply-To: <20220502080456.21568-1-u.kleine-koenig@pengutronix.de>

On Mon, May 02, 2022 at 10:04:56AM +0200, Uwe Kleine-König wrote:
> Returning an error value in an i2c remove callback results in an error
> message being emitted by the i2c core, but otherwise it doesn't make a
> difference. The device goes away anyhow and the devm cleanups are
> called.
> 
> In this case the remove callback even returns early without stopping the
> tcpm worker thread and various timers. A work scheduled on the work
> queue, or a firing timer after tcpci_remove() returned probably results
> in a use-after-free situation because the regmap and driver data were
> freed. So better make sure that tcpci_unregister_port() is called even
> if disabling the irq failed.
> 
> Also emit a more specific error message instead of the i2c core's
> "remove failed (EIO), will be ignored" and return 0 to suppress the
> core's warning.
> 
> This patch is (also) a preparation for making i2c remove callbacks
> return void.
> 
> Fixes: 3ba76256fc4e ("usb: typec: tcpci: mask event interrupts when remove driver")
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
>  drivers/usb/typec/tcpm/tcpci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> index e07d26a3cd8e..f33e08eb7670 100644
> --- a/drivers/usb/typec/tcpm/tcpci.c
> +++ b/drivers/usb/typec/tcpm/tcpci.c
> @@ -877,7 +877,7 @@ static int tcpci_remove(struct i2c_client *client)
>  	/* Disable chip interrupts before unregistering port */
>  	err = tcpci_write16(chip->tcpci, TCPC_ALERT_MASK, 0);
>  	if (err < 0)
> -		return err;
> +		dev_warn(&client->dev, "Failed to disable irqs (%pe)\n", ERR_PTR(err));
>  
>  	tcpci_unregister_port(chip->tcpci);
>  
> 
> base-commit: 3123109284176b1532874591f7c81f3837bbdc17
> -- 
> 2.35.1

thanks,

-- 
heikki