linux-kernel - Re: [PATCH -next] staging: r8188eu: fix missing unlock in rtw

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Date:   Thu, 28 Oct 2021 12:40:14 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     linux-kernel@...r.kernel.org, linux-staging@...ts.linux.dev,
        Yang Yingliang <yangyingliang@...wei.com>
Cc:     Larry.Finger@...inger.net, phil@...lpotter.co.uk,
        gregkh@...uxfoundation.org
Subject: Re: [PATCH -next] staging: r8188eu: fix missing unlock in rtw_resume()

On Thursday, October 28, 2021 11:40:38 AM CEST Yang Yingliang wrote:
> Add the missing unlock before return from rtw_resume().
> 
> Reported-by: Hulk Robot <hulkci@...wei.com>
> Fixes: 2b42bd58b321 ("staging: r8188eu: introduce new os_dep dir for 
RTL8188eu driver")
> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
> ---
>  drivers/staging/r8188eu/os_dep/usb_intf.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/r8188eu/os_dep/usb_intf.c b/drivers/staging/
r8188eu/os_dep/usb_intf.c
> index 6b93830130e7..5a35d9fe3fc9 100644
> --- a/drivers/staging/r8188eu/os_dep/usb_intf.c
> +++ b/drivers/staging/r8188eu/os_dep/usb_intf.c
> @@ -298,8 +298,10 @@ static int rtw_resume(struct usb_interface *pusb_intf)
>  		pwrpriv->bkeepfwalive = false;
>  
>  	DBG_88E("bkeepfwalive(%x)\n", pwrpriv->bkeepfwalive);
> -	if (pm_netdev_open(pnetdev, true) != 0)
> +	if (pm_netdev_open(pnetdev, true) != 0) {
> +		mutex_unlock(&pwrpriv->lock);
>  		goto exit;
> +	}
>  
>  	netif_device_attach(pnetdev);
>  	netif_carrier_on(pnetdev);
> -- 
> 2.25.1
> 
Good catch, well done!

I recently replaced semaphores with mutexes in this and other r8188eu driver
functions (commit 7e4c7947b42c "staging: r8188eu: Use a Mutex instead of a
binary semaphore") but, while making those changes, I didn't notice that the
'if' in rtw_resume () can lead to a jump to the "exit" label without properly
unlocking the "pwrpriv-> lock" mutex.

Acked-by: Fabio M. De Francesco <fmdefrancesco@...il.com>

Thank you,

Fabio