Re: [PATCH v4 2/4] serial: sh-sci: Fix crash in rx_timer_fn() on PIO fallback

[Geert Uytterhoeven <geert@linux-m68k.org>]

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

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds