linux-kernel - Re: [PATCH] clk: Fix CLK_SET_RATE_GATE flag validation in clk_set

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: <258a747f-c7d8-4f15-8446-2c18fe21ccf3@email.android.com>
Date:	Wed, 16 May 2012 06:31:23 +0800
From:	Richard Zhao <richard.zhao@...aro.org>
To:	Saravana Kannan <skannan@...eaurora.org>,
	linux-arm-kernel@...ts.infradead.org,
	Mike Turquette <mturquette@...aro.org>,
	Paul Walmsley <paul@...an.com>,
	Shawn Guo <shawn.guo@...escale.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Rob Herring <rob.herring@...xeda.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Russell King <linux@....linux.org.uk>
CC:	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	Andrew Lunn <andrew@...n.ch>,
	Jeremy Kerr <jeremy.kerr@...onical.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Arnd Bergman <arnd.bergmann@...aro.org>,
	Jamie Iles <jamie@...ieiles.com>,
	Magnus Damm <magnus.damm@...il.com>,
	Linus Walleij <linus.walleij@...ricsson.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Amit Kucheria <amit.kucheria@...aro.org>,
	Deepak Saxena <dsaxena@...aro.org>,
	Grant Likely <grant.likely@...retlab.ca>
Subject: Re: [PATCH] clk: Fix CLK_SET_RATE_GATE flag validation in clk_set_rate().



Saravana Kannan <skannan@...eaurora.org> wrote:

>The clk_set_rate() code shouldn't check the clock's enable count when
>validating CLK_SET_RATE_GATE flag since the enable count could change
>after
>the validation. Similar to clk_set_parent(), it should instead check
>the
>prepare count. The prepare count should go to zero only when the end
>user
>expects the clock to not be enabled in the future. Since the code
>already
>grabs the prepare count before validation, it's not possible for
>prepare
>count to change after validation and by association not possible for a
>well
>behaving end user to enable the clock while the set rate is in
>progress.
>
>Signed-off-by: Saravana Kannan <skannan@...eaurora.org>
>---
>Please let me know if you don't want me to directly email or CC you in
>my
>clock related patches. I don't want to spam anyone. Also, let me know
>if
>you want me add you to my standard list of people to cc in my clock
>patches.
>
> drivers/clk/clk.c |    2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
>diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>index 09b9112..f5b9d3c 100644
>--- a/drivers/clk/clk.c
>+++ b/drivers/clk/clk.c
>@@ -903,7 +903,7 @@ int clk_set_rate(struct clk *clk, unsigned long
>rate)
> 	if (rate == clk->rate)
> 		goto out;
> 
>-	if ((clk->flags & CLK_SET_RATE_GATE) && __clk_is_enabled(clk)) {
>+	if ((clk->flags & CLK_SET_RATE_GATE) && clk->prepare_count) {
The condition becomes more strict. Looks good.

> 		ret = -EBUSY;
> 		goto out;
> 	}
>-- 
>1.7.8.3
>
>Sent by an employee of the Qualcomm Innovation Center, Inc.
>The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
>Forum.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/