linux-kernel - Re: [PATCH] Input: cyapa_gen3: use msleep() for long delay

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20170115232010.GE23285@dtor-ws>
Date:   Sun, 15 Jan 2017 15:20:10 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Nicholas Mc Guire <hofrat@...dl.org>
Cc:     Henrik Rydberg <rydberg@...math.org>, Dudley Du <dudl@...ress.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input: cyapa_gen3: use msleep() for long delay

On Sun, Jan 15, 2017 at 12:13:07PM +0100, Nicholas Mc Guire wrote:
> ulseep_range() uses hrtimers and provides no advantage over msleep()
> for larger delays. Fix up the 50ms delays here to use msleep() and
> reduce the load on the hrtimer subsystem. 
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>

Applied, thank you.

> ---
> Problem found by coccinelle script
> 
> As the needed delay is specified in the comment as being "at least 50ms"
> the msleep(50) should be fine here. 
> 
> Note that cyapa_gen3_bl_exit() is returning -EAGAIN in cases where it was
> not yet ready to process the request, but the calling side 
> cyapa_gen3_do_operational_check() does not check for -EAGAIN so in case of
> the noted increased delay "...can take up to an additional 2 seconds. If 
> the device power is running low, this may take even longer", maybe
> cyapa_gen3_do_operational_check() may need a retry loop on -EAGAIN ?
> 
> Patch was compile tested with: x86_64_defconfig + CONFIG_MOUSE_CYAPA=m
> 
> Patch is against 4.10-rc3 (localversion-next is next-20170113)
> 
>  drivers/input/mouse/cyapa_gen3.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/mouse/cyapa_gen3.c b/drivers/input/mouse/cyapa_gen3.c
> index f9600753..6e9ecb0 100644
> --- a/drivers/input/mouse/cyapa_gen3.c
> +++ b/drivers/input/mouse/cyapa_gen3.c
> @@ -562,7 +562,7 @@ static int cyapa_gen3_bl_exit(struct cyapa *cyapa)
>  	 * Wait for bootloader to exit, and operation mode to start.
>  	 * Normally, this takes at least 50 ms.
>  	 */
> -	usleep_range(50000, 100000);
> +	msleep(50);
>  	/*
>  	 * In addition, when a device boots for the first time after being
>  	 * updated to new firmware, it must first calibrate its sensors, which
> -- 
> 2.1.4
> 

-- 
Dmitry