linux-kernel - Re: [PATCH] clocksource/drivers/time-armada-370-xp: Fix the clock reference

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

Message-ID: <20160810140652.2d59e12b@free-electrons.com>
Date:	Wed, 10 Aug 2016 14:06:52 +0200
From:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
To:	Gregory CLEMENT <gregory.clement@...e-electrons.com>
Cc:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
	Romain Perier <romain.perier@...e-electrons.com>,
	Jason Cooper <jason@...edaemon.net>,
	Boris BREZILLON <boris.brezillon@...e-electrons.com>,
	Stefan Roese <stefan.roese@...il.com>,
	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>,
	Sebastian Careba <nitroshift@...oo.com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	linux-arm-kernel@...ts.infradead.org,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Subject: Re: [PATCH] clocksource/drivers/time-armada-370-xp: Fix the clock
 reference

Hello,

On Wed, 10 Aug 2016 10:09:08 +0200, Gregory CLEMENT wrote:
> While converting the init function to return an error, the wrong clock
> was get. This lead to wrong clock rate and slow down the kernel. For
> example, before the patch a typical boot was around 15s after it was 1
> minute slower.
> 
> Fixes: 12549e27c63c ("clocksource/drivers/time-armada-370-xp: Convert init function to return error")
> 
> Signed-off-by: Gregory CLEMENT <gregory.clement@...e-electrons.com>
> ---
>  drivers/clocksource/time-armada-370-xp.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/clocksource/time-armada-370-xp.c b/drivers/clocksource/time-armada-370-xp.c
> index 719b478d136e..3c39e6f45971 100644
> --- a/drivers/clocksource/time-armada-370-xp.c
> +++ b/drivers/clocksource/time-armada-370-xp.c
> @@ -338,7 +338,6 @@ static int __init armada_xp_timer_init(struct device_node *np)
>  	struct clk *clk = of_clk_get_by_name(np, "fixed");
>  	int ret;
>  
> -	clk = of_clk_get(np, 0);

I think to avoid this mistake, we should rewrite the code as:

	struct *clk;
	int ret;

	clk = of_clk_get_by_name(np, "fixed");
	if (IS_ERR(clk)) {
		...
	

Indeed, I find confusing a block that starts with error checking, and
it's probably what lead to this of_clk_get() being added here.

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com