linux-kernel - Re: [PATCH] fbdev/hpfb: Fix an error handling path in hpfb_dio

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Message-ID: <698958fb-4fc8-4288-b067-5843c651b093@gmx.de>
Date: Mon, 29 Jul 2024 10:13:17 +0200
From: Helge Deller <deller@....de>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
 linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] fbdev/hpfb: Fix an error handling path in
 hpfb_dio_probe()

On 7/28/24 20:29, Christophe JAILLET wrote:
> If an error occurs after request_mem_region(), a corresponding
> release_mem_region() should be called, as already done in the remove
> function.

True.

> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")

I think we can drop this "Fixes" tag, as it gives no real info.

> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> *Not* even compile tested only.

Ok.

> I don't know on what architecture it relies on.

HP300 are old HP machines with an m68k CPU.
Not sure if someone still has such a machine :-)

> So it is provided as-is
> ---
>   drivers/video/fbdev/hpfb.c | 15 ++++++++++-----
>   1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/video/fbdev/hpfb.c b/drivers/video/fbdev/hpfb.c
> index 66fac8e5393e..87b8dcdc1cf3 100644
> --- a/drivers/video/fbdev/hpfb.c
> +++ b/drivers/video/fbdev/hpfb.c
> @@ -342,12 +342,17 @@ static int hpfb_dio_probe(struct dio_dev *d, const struct dio_device_id *ent)
>   	}
>   	printk(KERN_INFO "Topcat found at DIO select code %d "
>   	       "(secondary id %02x)\n", d->scode, (d->id >> 8) & 0xff);
> -	if (hpfb_init_one(paddr, vaddr)) {
> -		if (d->scode >= DIOII_SCBASE)
> -			iounmap((void *)vaddr);

This driver hasn't changed in years, and I don't expect we will
have many other changes, so in this case I think simply adding the one line:
+	release_mem_region(d->resource.start, resource_size(&d->resource));
here is sufficient without adding additional jump targets.

I can fix it up here, or please send a new patch.

Helge


> -		return -ENOMEM;
> -	}
> +	if (hpfb_init_one(paddr, vaddr))
> +		goto err_unmap;
> +
>   	return 0;
> +
> +err_unmap:
> +	if (d->scode >= DIOII_SCBASE)
> +		iounmap((void *)vaddr);
> +	release_mem_region(d->resource.start, resource_size(&d->resource));
> +
> +	return -ENOMEM;
>   }
>
>   static void hpfb_remove_one(struct dio_dev *d)