linux-kernel - Re: [PATCH] media: isif: reset global state

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Date:   Fri, 17 Jul 2020 10:55:13 +0100
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Evgeny Novikov <novikov@...ras.ru>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media <linux-media@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, ldv-project@...uxtesting.org
Subject: Re: [PATCH] media: isif: reset global state

HI Evgeny,

Thank you for the patch.

On Tue, Jul 14, 2020 at 6:20 PM Evgeny Novikov <novikov@...ras.ru> wrote:
>
> isif_probe() invokes iounmap() on error handling paths, but it does not
> reset the global state. So, later it can invoke iounmap() even when
> ioremap() fails. This is the case also for isif_remove(). The patch
> resets the global state after invoking iounmap() to avoid this.
>
> Found by Linux Driver Verification project (linuxtesting.org).
>
> Signed-off-by: Evgeny Novikov <novikov@...ras.ru>
> ---
>  drivers/media/platform/davinci/isif.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/platform/davinci/isif.c b/drivers/media/platform/davinci/isif.c
> index c98edb67cfb2..c53cecd072b1 100644
> --- a/drivers/media/platform/davinci/isif.c
> +++ b/drivers/media/platform/davinci/isif.c
> @@ -1075,10 +1075,14 @@ static int isif_probe(struct platform_device *pdev)
>         release_mem_region(res->start, resource_size(res));
>         i--;
>  fail_nobase_res:
> -       if (isif_cfg.base_addr)
> +       if (isif_cfg.base_addr) {
>                 iounmap(isif_cfg.base_addr);
> -       if (isif_cfg.linear_tbl0_addr)
> +               isif_cfg.base_addr = NULL;
> +       }
> +       if (isif_cfg.linear_tbl0_addr) {
>                 iounmap(isif_cfg.linear_tbl0_addr);
> +               isif_cfg.linear_tbl0_addr = NULL;
> +       }
>
As the probe itself is failing I don't see a benefit in setting the
pointers to NULL. Unless I'm missing something.

Cheers,
--Prabhakar

>         while (i >= 0) {
>                 res = platform_get_resource(pdev, IORESOURCE_MEM, i);
> @@ -1096,8 +1100,11 @@ static int isif_remove(struct platform_device *pdev)
>         int i = 0;
>
>         iounmap(isif_cfg.base_addr);
> +       isif_cfg.base_addr = NULL;
>         iounmap(isif_cfg.linear_tbl0_addr);
> +       isif_cfg.linear_tbl0_addr = NULL;
>         iounmap(isif_cfg.linear_tbl1_addr);
> +       isif_cfg.linear_tbl1_addr = NULL;
>         while (i < 3) {
>                 res = platform_get_resource(pdev, IORESOURCE_MEM, i);
>                 if (res)
> --
> 2.16.4
>