linux-kernel - Re: [PATCH v2] p54: Fix an error handling path in p54spi

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Date:   Thu, 16 Jun 2022 13:36:40 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Christian Lamparter <chunkeey@...il.com>
Cc:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Kalle Valo <kvalo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "John W. Linville" <linville@...driver.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        Christian Lamparter <chunkeey@....de>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH v2] p54: Fix an error handling path in p54spi_probe()

On Wed, Jun 15, 2022 at 11:03:34PM +0200, Christian Lamparter wrote:
> On 13/06/2022 22:57, Christophe JAILLET wrote:
> > Le 13/06/2022 à 22:02, Christian Lamparter a écrit :
> > > On Sun, Jun 12, 2022 at 11:12 PM Christophe JAILLET
> > > <christophe.jaillet@...adoo.fr> wrote:
> > > > 
> > > > If an error occurs after a successful call to p54spi_request_firmware(), it
> > > > must be undone by a corresponding release_firmware() as already done in
> > > > the error handling path of p54spi_request_firmware() and in the .remove()
> > > > function.
> > > > 
> > > > Add the missing call in the error handling path and remove it from
> > > > p54spi_request_firmware() now that it is the responsibility of the caller
> > > > to release the firmawre
> > > 
> > > that last word hast a typo:  firmware. (maybe Kalle can fix this in post).
> > 
> > More or less the same typo twice in a row... _Embarrassed_
> > 
> > > 
> > > > Fixes: cd8d3d321285 ("p54spi: p54spi driver")
> > > > Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> > > Acked-by: Christian Lamparter <chunkeey@...il.com>
> > > (Though, v1 was fine too.)
> > > > ---
> > > > v2: reduce diffstat and take advantage on the fact that release_firmware()
> > > > checks for NULL
> > > 
> > > Heh, ok ;) . Now that I see it,  the "ret = p54_parse_firmware(...); ... "
> > > could have been replaced with "return p54_parse_firmware(dev, priv->firmware);"
> > > so the p54spi.c could shrink another 5-6 lines.
> > > 
> > > I think leaving p54spi_request_firmware() callee to deal with
> > > releasing the firmware
> > > in the error case as well is nicer because it gets rid of a "but in
> > > this case" complexity.
> > 
> > 
> > Take the one you consider being the best one.
> 
> well said!
> 
> > 
> > If it deserves a v3 to axe some lines of code, I can do it but, as said
> > previously,
> > v1 is for me the cleaner and more future proof.
> 
> Gee, that last sentence about "future proof" is daring.

The future is vast and unknowable but one thing which is pretty likely
is that Christophe's patch will introduce a static checker warning.  We
really would have expected a to find a release_firmware() in the place
where it was in the original code.  There is a comment there now so no
one is going to re-add the release_firmware() but that's been an issue
in the past.

I'm sort of surprised that it wasn't a static checker warning already.
Anyway, I'll add this to Smatch check_unwind.c

+         { "request_firmware", ALLOC, 0, "*$", &int_zero, &int_zero},
+         { "release_firmware", RELEASE, 0, "$"},

regards,
dan carpenter