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List:       linux-sh
Subject:    Re: [PATCH v4 2/4] serial: sh-sci: Fix crash in rx_timer_fn() on PIO fallback
From:       Simon Horman <horms () verge ! net ! au>
Date:       2018-12-17 14:50:44
Message-ID: 20181217145043.ygw2lwtw2v5i4lpm () verge ! net ! au
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On Mon, Dec 17, 2018 at 02:27:47PM +0100, Geert Uytterhoeven wrote:
> Hi Simon,
> 
> On Mon, Dec 17, 2018 at 2:22 PM Simon Horman <horms@verge.net.au> wrote:
> > On Thu, Dec 13, 2018 at 07:44:42PM +0100, Geert Uytterhoeven wrote:
> > > When falling back to PIO, active_rx must be set to a different value
> > > than cookie_rx[i], else sci_dma_rx_find_active() will incorrectly find a
> > > match, leading to a NULL pointer dereference in rx_timer_fn() later.
> > >
> > > Use zero instead, which is the same value as after driver
> > > initialization.
> > >
> > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> >
> > This looks good so to me long as dmaengine_submit() doesn't return 0.
> > Is that the case?
> 
> include/linux/dmaengine.h:
> 
> /**
>  * typedef dma_cookie_t - an opaque DMA cookie
>  *
>  * if dma_cookie_t is >0 it's a DMA request cookie, <0 it's an error code
>  */
> typedef s32 dma_cookie_t;
> #define DMA_MIN_COOKIE  1

In that case I have no objections.

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>

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