linux-kernel - Re: [PATCH] drm/radeon/r100: enhance error handling in r100_cp_init

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Date: Mon, 27 May 2024 09:58:11 +0200
From: Christian König <christian.koenig@....com>
To: Zhouyi Zhou <zhouzhouyi@...il.com>, alexander.deucher@....com,
 Xinhui.Pan@....com, airlied@...il.com, daniel@...ll.ch,
 chris@...isdown.name, amd-gfx@...ts.freedesktop.org,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 rcu@...r.kernel.org, lance@...osl.org
Subject: Re: [PATCH] drm/radeon/r100: enhance error handling in
 r100_cp_init_microcode

Am 27.05.24 um 03:20 schrieb Zhouyi Zhou:
> In r100_cp_init_microcode, if rdev->family don't match any of
> if statement,  fw_name will be NULL, which will cause
> gcc (11.4.0 powerpc64le-linux-gnu) complain:
>
> In function ‘r100_cp_init_microcode’,
>      inlined from ‘r100_cp_init’ at drivers/gpu/drm/radeon/r100.c:1136:7:
> ./include/linux/printk.h:457:44: warning: ‘%s’ directive argument is null [-Wformat-overflow=]
>    457 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
>
> Above warning is emitted during the rcutorture test in
> in PPC VM of Opensource Lab of Oregon State Univerisity.
>
> Enhance error handling in r100_cp_init_microcode, let r100_cp_init_microcode
> return with -EINVAL when none of chip families is matched.
>
> Signed-off-by: Zhouyi Zhou <zhouzhouyi@...il.com>

> ---
>   drivers/gpu/drm/radeon/r100.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
> index 0b1e19345f43..4f8a1bdd9365 100644
> --- a/drivers/gpu/drm/radeon/r100.c
> +++ b/drivers/gpu/drm/radeon/r100.c
> @@ -1055,6 +1055,11 @@ static int r100_cp_init_microcode(struct radeon_device *rdev)
>   		   (rdev->family == CHIP_RV570)) {
>   		DRM_INFO("Loading R500 Microcode\n");
>   		fw_name = FIRMWARE_R520;
> +	} else {
> +		pr_err("radeon_cp: Failed to load firmware \"%d\"\n",
> +			rdev->family);
> +		err = -EINVAL;
> +		goto out;
>   	}
>   
>   	err = request_firmware(&rdev->me_fw, fw_name, rdev->dev);
> @@ -1067,6 +1072,8 @@ static int r100_cp_init_microcode(struct radeon_device *rdev)
>   		release_firmware(rdev->me_fw);
>   		rdev->me_fw = NULL;
>   	}
> +
> +out:

That looks superfluous, just return -EINVAL directly in the else case above.

Apart from that this is for ~15year old hardware. I'm a bit reluctant 
adding code for something that old even when this change here looks 
harmless.

Is there a plan to complain about that in an automated checker? If yes 
then the change is probably justified, if no then I would rather not do it.

Regards,
Christian.

>   	return err;
>   }
>