2023-10-03 07:56:13

by Marvin Lin

Subject: [PATCH] media: nuvoton: npcm-video: Fix sleeping in atomic context

Fix sleeping in atomic context warnings reported by the Smatch static
analysis tool. Use GFP_ATOMIC instead of GFP_KERNEL in atomic context.

Fixes: 70721089985c ("media: nuvoton: Add driver for NPCM video capture and encoding engine")
Reported-by: Dan Carpenter <[email protected]>
Signed-off-by: Marvin Lin <[email protected]>
---
drivers/media/platform/nuvoton/npcm-video.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/nuvoton/npcm-video.c b/drivers/media/platform/nuvoton/npcm-video.c
index ac8d73b794d3..5d160978f7b3 100644
--- a/drivers/media/platform/nuvoton/npcm-video.c
+++ b/drivers/media/platform/nuvoton/npcm-video.c
@@ -412,7 +412,7 @@ static unsigned int npcm_video_add_rect(struct npcm_video *video,
struct rect_list *list = NULL;
struct v4l2_rect *r;

- list = kzalloc(sizeof(*list), GFP_KERNEL);
+ list = kzalloc(sizeof(*list), GFP_ATOMIC);
if (!list)
return 0;

@@ -467,7 +467,7 @@ static struct rect_list *npcm_video_new_rect(struct npcm_video *video,
struct rect_list *list = NULL;
struct v4l2_rect *r;

- list = kzalloc(sizeof(*list), GFP_KERNEL);
+ list = kzalloc(sizeof(*list), GFP_ATOMIC);
if (!list)
return NULL;

--
2.34.1

2023-10-03 13:23:33

by Hans Verkuil

Subject: Re: [PATCH] media: nuvoton: npcm-video: Fix sleeping in atomic context

On 10/3/23 09:55, Marvin Lin wrote:
> Fix sleeping in atomic context warnings reported by the Smatch static
> analysis tool. Use GFP_ATOMIC instead of GFP_KERNEL in atomic context.
>
> Fixes: 70721089985c ("media: nuvoton: Add driver for NPCM video capture and encoding engine")
> Reported-by: Dan Carpenter <[email protected]>
> Signed-off-by: Marvin Lin <[email protected]>
> ---
> drivers/media/platform/nuvoton/npcm-video.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/platform/nuvoton/npcm-video.c b/drivers/media/platform/nuvoton/npcm-video.c
> index ac8d73b794d3..5d160978f7b3 100644
> --- a/drivers/media/platform/nuvoton/npcm-video.c
> +++ b/drivers/media/platform/nuvoton/npcm-video.c
> @@ -412,7 +412,7 @@ static unsigned int npcm_video_add_rect(struct npcm_video *video,
> struct rect_list *list = NULL;
> struct v4l2_rect *r;
>
> - list = kzalloc(sizeof(*list), GFP_KERNEL);
> + list = kzalloc(sizeof(*list), GFP_ATOMIC);
> if (!list)
> return 0;
>
> @@ -467,7 +467,7 @@ static struct rect_list *npcm_video_new_rect(struct npcm_video *video,
> struct rect_list *list = NULL;
> struct v4l2_rect *r;
>
> - list = kzalloc(sizeof(*list), GFP_KERNEL);
> + list = kzalloc(sizeof(*list), GFP_ATOMIC);
> if (!list)
> return NULL;
>

I'm not really sure this is the right approach.

Looking closer at the code I notice that npcm_video_irq is a threaded
interrupt handler, so wouldn't it be easier to change the video->lock
spinlock to a mutex?

Regards,

Hans

2023-10-10 12:31:34

by Marvin Lin

Subject: Re: [PATCH] media: nuvoton: npcm-video: Fix sleeping in atomic context

Hi Hans,

Thanks for the review.

> > - list = kzalloc(sizeof(*list), GFP_KERNEL);
> > + list = kzalloc(sizeof(*list), GFP_ATOMIC);
> > if (!list)
> > return NULL;
> >
>
> I'm not really sure this is the right approach.
>
> Looking closer at the code I notice that npcm_video_irq is a threaded
> interrupt handler, so wouldn't it be easier to change the video->lock
> spinlock to a mutex?
>

Agree it's better to use mutex. Will send v2 for this.

Regards,
Marvin