linux-kernel - Re: [PATCH] spi: Avoid calling spi_slave

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Message-ID: <20191001114108.GA4786@sirena.co.uk>
Date:   Tue, 1 Oct 2019 12:41:08 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Lukasz Majewski <lukma@...x.de>,
        Colin Ian King <colin.king@...onical.com>,
        linux-spi <linux-spi@...r.kernel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        kbuild test robot <lkp@...el.com>,
        Julia Lawall <julia.lawall@...6.fr>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH] spi: Avoid calling spi_slave_abort() with kfreed spidev

On Tue, Oct 01, 2019 at 12:00:07PM +0200, Geert Uytterhoeven wrote:
> On Tue, Oct 1, 2019 at 11:34 AM Lukasz Majewski <lukma@...x.de> wrote:
> > > On Tue, Oct 1, 2019 at 11:07 AM Lukasz Majewski <lukma@...x.de> wrote:

> > The if (!dofree) prevents from calling spi_slave_abort() when
> > spidev->spi == NULL and spidev is kfree'd.

> If spidev->users != 0, the block checking spidev->spi == NULL is never
> executed, and spi_slave_abort() will be called.

> I'm wondering if spidev->spi can be NULL if spidev->users is still positive.

It *shouldn't* be.  I think we have other problems if it is.

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