linux-kernel - Re: [PATCH 6/11] drivers/dma: Correct NULL test

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Date:	Mon, 8 Feb 2010 14:07:52 -0700
From:	Dan Williams <dan.j.williams@...el.com>
To:	Julia Lawall <julia@...u.dk>,
	Linus Walleij <linus.walleij@...ricsson.com>
Cc:	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 6/11] drivers/dma: Correct NULL test

[ adding Linus in case this BUG_ON had a different intent, or can be deleted ]

On Sat, Feb 6, 2010 at 1:43 AM, Julia Lawall <julia@...u.dk> wrote:
> From: Julia Lawall <julia@...u.dk>
>
> cohd_fin has already been verified not to be NULL, so the argument to
> BUG_ON cannot be true.
>
> A simplified version of the semantic match that finds this problem is as
> follows: (http://coccinelle.lip6.fr/)
>
> // <smpl>
> @r@
> expression *x;
> expression e;
> identifier l;
> @@
>
> if (x == NULL || ...) {
>    ... when forall
>    return ...; }
> ... when != goto l;
>    when != x = e
>    when != &x
> *x == NULL
> // </smpl>
>
> Signed-off-by: Julia Lawall <julia@...u.dk>
>
> ---
>  drivers/dma/coh901318.c             |    2 --
>  1 files changed, 0 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/coh901318.c b/drivers/dma/coh901318.c
> index b5f2ee0..64a9372 100644
> --- a/drivers/dma/coh901318.c
> +++ b/drivers/dma/coh901318.c
> @@ -613,8 +613,6 @@ static void dma_tasklet(unsigned long data)
>        cohd_fin->pending_irqs--;
>        cohc->completed = cohd_fin->desc.cookie;
>
> -       BUG_ON(cohc->nbr_active_done && cohd_fin == NULL);
> -
>        if (cohc->nbr_active_done == 0)
>                return;
>
> --
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