linux-kernel - Re: [PATCH 2/5] video: Add missing annotation for cyber2000fb_enable_ddc() and cyber2000fb_disable_ddc()

Open Source and information security mailing list archives

Date:   Tue, 7 Apr 2020 21:48:24 +0200
From:   Sam Ravnborg <sam@...nborg.org>
To:     Jules Irenge <jbi.octave@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        "open list:FRAMEBUFFER LAYER" <linux-fbdev@...r.kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        boqun.feng@...il.com, Russell King <linux@...linux.org.uk>,
        "open list:FRAMEBUFFER LAYER" <dri-devel@...ts.freedesktop.org>,
        "moderated list:CYBERPRO FB DRIVER" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/5] video: Add missing annotation for
 cyber2000fb_enable_ddc() and cyber2000fb_disable_ddc()

Hi Jules.

On Fri, Apr 03, 2020 at 05:05:02PM +0100, Jules Irenge wrote:
> Sparse reports warnings at cyber2000fb_enable_ddc()
> 	and cyber2000fb_disable_ddc()
> 
> warning: context imbalance in cyber2000fb_enable_ddc()
> 	- wrong count at exit
> 
> warning: context imbalance in cyber2000fb_disable_ddc()
> 	- unexpected unlock
> 
> The root cause is the missing annotation at cyber2000fb_enable_ddc()
> 	and cyber2000fb_disable_ddc()
> 
> Add the missing __acquires(&cfb->reg_b0_lock) annotation
> Add the missing __releases(&cfb->reg_b0_lock) annotation
> 
> Signed-off-by: Jules Irenge <jbi.octave@...il.com>

Thanks, added to drm-misc-next, so the patch will hit the kernel
when the merge windows opens the next time.

Was this the only locking relevant warning in fbdev?
I would expect a few more.

	Sam

> ---
>  drivers/video/fbdev/cyber2000fb.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/video/fbdev/cyber2000fb.c b/drivers/video/fbdev/cyber2000fb.c
> index 460826a7ad55..513f58f28b0f 100644
> --- a/drivers/video/fbdev/cyber2000fb.c
> +++ b/drivers/video/fbdev/cyber2000fb.c
> @@ -1160,12 +1160,14 @@ EXPORT_SYMBOL(cyber2000fb_detach);
>  #define DDC_SDA_IN	(1 << 6)
>  
>  static void cyber2000fb_enable_ddc(struct cfb_info *cfb)
> +	__acquires(&cfb->reg_b0_lock)
>  {
>  	spin_lock(&cfb->reg_b0_lock);
>  	cyber2000fb_writew(0x1bf, 0x3ce, cfb);
>  }
>  
>  static void cyber2000fb_disable_ddc(struct cfb_info *cfb)
> +	__releases(&cfb->reg_b0_lock)
>  {
>  	cyber2000fb_writew(0x0bf, 0x3ce, cfb);
>  	spin_unlock(&cfb->reg_b0_lock);
> -- 
> 2.24.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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