linux-kernel - Re: [PATCH 2/2] bdisp: Fix a possible sleep-in-atomic bug in bdisp_hw_save

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Date:   Fri, 15 Dec 2017 14:53:27 +0000
From:   Fabien DESSENNE <fabien.dessenne@...com>
To:     Jia-Ju Bai <baijiaju1990@...il.com>,
        "mchehab@...nel.org" <mchehab@...nel.org>
CC:     "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Benjamin GAIGNARD" <benjamin.gaignard@...com>,
        Hans Verkuil <hverkuil@...all.nl>
Subject: Re: [PATCH 2/2] bdisp: Fix a possible sleep-in-atomic bug in
 bdisp_hw_save_request

Hi


Thank you for the patch.


On 12/12/17 14:47, Jia-Ju Bai wrote:
> The driver may sleep under a spinlock.
> The function call path is:
> bdisp_device_run (acquire the spinlock)
>    bdisp_hw_update
>      bdisp_hw_save_request
>        devm_kzalloc(GFP_KERNEL) --> may sleep
>
> To fix it, GFP_KERNEL is replaced with GFP_ATOMIC.
>
> This bug is found by my static analysis tool(DSAC) and checked by my code review.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
Reviewed-by: Fabien Dessenne <fabien.dessenne@...com>
> ---
>   drivers/media/platform/sti/bdisp/bdisp-hw.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/sti/bdisp/bdisp-hw.c b/drivers/media/platform/sti/bdisp/bdisp-hw.c
> index 4b62ceb..7b45b43 100644
> --- a/drivers/media/platform/sti/bdisp/bdisp-hw.c
> +++ b/drivers/media/platform/sti/bdisp/bdisp-hw.c
> @@ -1064,7 +1064,7 @@ static void bdisp_hw_save_request(struct bdisp_ctx *ctx)
>   		if (!copy_node[i]) {
>   			copy_node[i] = devm_kzalloc(ctx->bdisp_dev->dev,
>   						    sizeof(*copy_node[i]),
> -						    GFP_KERNEL);
> +						    GFP_ATOMIC);
>   			if (!copy_node[i])
>   				return;
>   		}