linux-kernel - Re: [PATCH v3] video: fbdev: arcfb: add missed free_irq and fix the order of request

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Date:   Fri, 20 Mar 2020 12:48:54 +0100
From:   Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:     Chuhong Yuan <hslester96@...il.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] video: fbdev: arcfb: add missed free_irq and fix the
 order of request_irq


On 3/10/20 3:30 PM, Chuhong Yuan wrote:
> The driver forgets to free irq in remove which is requested in
> probe.
> Add the missed call to fix it.
> Also, the position of request_irq() in probe should be put before
> register_framebuffer().
> 
> Signed-off-by: Chuhong Yuan <hslester96@...il.com>
> ---
> Changes in v3:
>   - Add missed variable par in remove.
> 
>  drivers/video/fbdev/arcfb.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/video/fbdev/arcfb.c b/drivers/video/fbdev/arcfb.c
> index 314ab82e01c0..9a720c14056c 100644
> --- a/drivers/video/fbdev/arcfb.c
> +++ b/drivers/video/fbdev/arcfb.c
> @@ -544,10 +544,6 @@ static int arcfb_probe(struct platform_device *dev)
>  	par->cslut[1] = 0x06;
>  	info->flags = FBINFO_FLAG_DEFAULT;
>  	spin_lock_init(&par->lock);
> -	retval = register_framebuffer(info);
> -	if (retval < 0)
> -		goto err1;
> -	platform_set_drvdata(dev, info);
>  	if (irq) {
>  		par->irq = irq;
>  		if (request_irq(par->irq, &arcfb_interrupt, IRQF_SHARED,
> @@ -558,6 +554,10 @@ static int arcfb_probe(struct platform_device *dev)
>  			goto err1;
>  		}
>  	}
> +	retval = register_framebuffer(info);
> +	if (retval < 0)
> +		goto err1;
> +	platform_set_drvdata(dev, info);
>  	fb_info(info, "Arc frame buffer device, using %dK of video memory\n",
>  		videomemorysize >> 10);
>  
> @@ -590,9 +590,12 @@ static int arcfb_probe(struct platform_device *dev)
>  static int arcfb_remove(struct platform_device *dev)
>  {
>  	struct fb_info *info = platform_get_drvdata(dev);
> +	struct arcfb_par *par = info->par;

Please look at the line below, 'info' is checked for being NULL so
either 'par = info->par' can dereference NULL pointer or the check is
superfluous and should be removed.

Also there is no need for 'par' variable (it is used only once),
why not simply use info->par->irq in free_irq() call below?

>  	if (info) {
>  		unregister_framebuffer(info);
> +		if (irq)
> +			free_irq(par->irq, info);
>  		vfree((void __force *)info->screen_base);
>  		framebuffer_release(info);
>  	}

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics