linux-kernel - Re: [PATCH] staging: fix ignoring return value warning

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Date:   Mon, 8 Feb 2021 16:06:18 +0100
From:   Sascha Hauer <sha@...gutronix.de>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Youling Tang <tangyouling@...ngson.cn>, devel@...verdev.osuosl.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] staging: fix ignoring return value warning

Hi Dan,

On Mon, Feb 08, 2021 at 04:45:17PM +0300, Dan Carpenter wrote:
> On Sun, Feb 07, 2021 at 05:23:28PM +0800, Youling Tang wrote:
> > Fix the below ignoring return value warning for device_reset.
> > 
> > drivers/staging/mt7621-dma/mtk-hsdma.c:685:2: warning: ignoring return value
> > of function declared with 'warn_unused_result' attribute [-Wunused-result]
> >         device_reset(&pdev->dev);
> >         ^~~~~~~~~~~~ ~~~~~~~~~~
> > drivers/staging/ralink-gdma/ralink-gdma.c:836:2: warning: ignoring return value
> > of function declared with 'warn_unused_result' attribute [-Wunused-result]
> >         device_reset(&pdev->dev);
> >         ^~~~~~~~~~~~ ~~~~~~~~~~
> > 
> 
> We can't really do this sort of fix without the hardware to test it.
> This could be the correct fix or perhaps switching to device_reset_optional()
> is the correct fix.  We can't know unless we have the hardware to test.

When device_reset() is the wrong function then adding a return value
check will turn this into a runtime error for those who have the
hardware which will hopefully trigger them to tell us why reset_device
is wrong for them.
At least for a staging driver I find this procedure opportune.

Sascha

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