linux-kernel - Re: [PATCH v7 2/4] media: pisp_be: Remove config validation from schedule()

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Message-ID: <CAEmqJPod6cKh2z1f4qFatcAdQ7m1GoBNQrYVESHb1UehNv1c6A@mail.gmail.com>
Date: Fri, 13 Jun 2025 09:31:56 +0100
From: Naushir Patuck <naush@...pberrypi.com>
To: Jacopo Mondi <jacopo.mondi@...asonboard.com>
Cc: Nick Hollinghurst <nick.hollinghurst@...pberrypi.com>, 
	David Plowman <david.plowman@...pberrypi.com>, 
	Dave Stevenson <dave.stevenson@...pberrypi.com>, 
	Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
	Raspberry Pi Kernel Maintenance <kernel-list@...pberrypi.com>, Mauro Carvalho Chehab <mchehab@...nel.org>, 
	Florian Fainelli <florian.fainelli@...adcom.com>, 
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, 
	Sakari Ailus <sakari.ailus@...ux.intel.com>, Hans Verkuil <hverkuil@...all.nl>, 
	linux-media@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/4] media: pisp_be: Remove config validation from schedule()

Hi Jacopo,

Thank you for this patch.

On Fri, 6 Jun 2025 at 11:29, Jacopo Mondi <jacopo.mondi@...asonboard.com> wrote:
>
> The config parameters buffer is already validated in
> pisp_be_validate_config() at .buf_prepare() time.
>
> However some of the same validations are also performed at
> pispbe_schedule() time. In particular the function checks that:
>
> 1) config.num_tiles is valid
> 2) At least one of the BAYER or RGB input is enabled
>
> The input config validation is already performed in
> pisp_be_validate_config() and while job.hw_enables is modified by
> pispbe_xlate_addrs(), the function only resets the input masks if
>
> - there is no input buffer available, but pispbe_prepare_job() fails
>   before calling pispbe_xlate_addrs() in this case
> - bayer_enable is 0, but in this case rgb_enable is valid as guaranteed
>   by pisp_be_validate_config()
> - only outputs are reset in rgb_enable
>
> For this reasons there is no need to repeat the check at
> pispbe_schedule() time.
>
> The num_tiles validation can be moved to pisp_be_validate_config() as
> well. As num_tiles is a u32 it can'be be < 0, so change the sanity
> check accordingly.
>
> Signed-off-by: Jacopo Mondi <jacopo.mondi@...asonboard.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

Reviewed-by: Naushir Patuck <naush@...pberrypi.com>

> ---
>  .../media/platform/raspberrypi/pisp_be/pisp_be.c   | 25 ++++++----------------
>  1 file changed, 7 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/media/platform/raspberrypi/pisp_be/pisp_be.c b/drivers/media/platform/raspberrypi/pisp_be/pisp_be.c
> index b1449245f394..92c452891d6c 100644
> --- a/drivers/media/platform/raspberrypi/pisp_be/pisp_be.c
> +++ b/drivers/media/platform/raspberrypi/pisp_be/pisp_be.c
> @@ -588,24 +588,6 @@ static void pispbe_schedule(struct pispbe_dev *pispbe, bool clear_hw_busy)
>         pispbe->hw_busy = true;
>         spin_unlock_irqrestore(&pispbe->hw_lock, flags);
>
> -       if (job.config->num_tiles <= 0 ||
> -           job.config->num_tiles > PISP_BACK_END_NUM_TILES ||
> -           !((job.hw_enables.bayer_enables | job.hw_enables.rgb_enables) &
> -             PISP_BE_BAYER_ENABLE_INPUT)) {
> -               /*
> -                * Bad job. We can't let it proceed as it could lock up
> -                * the hardware, or worse!
> -                *
> -                * For now, just force num_tiles to 0, which causes the
> -                * H/W to do something bizarre but survivable. It
> -                * increments (started,done) counters by more than 1,
> -                * but we seem to survive...
> -                */
> -               dev_dbg(pispbe->dev, "Bad job: invalid number of tiles: %u\n",
> -                       job.config->num_tiles);
> -               job.config->num_tiles = 0;
> -       }
> -
>         pispbe_queue_job(pispbe, &job);
>
>         return;
> @@ -703,6 +685,13 @@ static int pisp_be_validate_config(struct pispbe_dev *pispbe,
>                 return -EIO;
>         }
>
> +       if (config->num_tiles == 0 ||
> +           config->num_tiles > PISP_BACK_END_NUM_TILES) {
> +               dev_dbg(dev, "%s: Invalid number of tiles: %d\n", __func__,
> +                       config->num_tiles);
> +               return -EINVAL;
> +       }
> +
>         /* Ensure output config strides and buffer sizes match the V4L2 formats. */
>         fmt = &pispbe->node[TDN_OUTPUT_NODE].format;
>         if (bayer_enables & PISP_BE_BAYER_ENABLE_TDN_OUTPUT) {
>
> --
> 2.49.0
>