linux-kernel - Re: [PATCH B 01/10] OMAP2/3 clock: combine clkdm, clkdm

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Date:	Wed, 4 Feb 2009 15:47:23 -0700 (MST)
From:	Paul Walmsley <paul@...an.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
cc:	linux-arm-kernel@...ts.arm.linux.org.uk,
	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
	Tony Lindgren <tony@...mide.com>
Subject: Re: [PATCH B 01/10] OMAP2/3 clock: combine clkdm, clkdm_name into
 union in struct clk

Hi Russell,

On Tue, 3 Feb 2009, Paul Walmsley wrote:

> On Sat, 31 Jan 2009, Russell King - ARM Linux wrote:
> 
> > On Tue, Jan 27, 2009 at 07:44:08PM -0700, Paul Walmsley wrote:
> > > diff --git a/arch/arm/mach-omap2/clock.c b/arch/arm/mach-omap2/clock.c
> > > index 55c5d67..7aa09f5 100644
> > > --- a/arch/arm/mach-omap2/clock.c
> > > +++ b/arch/arm/mach-omap2/clock.c
> > > @@ -77,17 +77,17 @@ void omap2_init_clk_clkdm(struct clk *clk)

...

> > This is unsafe - if the clock domain can not be found, you leave the
> > union pointing at the string, and there's no way for this to prevent
> > the clock from being registered.
> 
> Agreed.  Now that omap2_init_clk_clkdm() is called by the 
> OMAP arch-specific clk_register(), this should be pretty easy to 
> implement.  Will send a patch that applies on top of F 06.

The following patch prevents a clock with a bad or missing clockdomain 
from registering.  It applies after F 06.


- Paul


From: Paul Walmsley <paul@...an.com>
Date: Wed, 4 Feb 2009 15:11:20 -0700

OMAP2/3 clock: prevent clock registration with bad or missing clockdomain

If clk_register() is called on a struct clk without a clockdomain
name, or a struct clk which contains an invalid clockdomain name, fail
the clock registration.  This prevents later code from inadvertently
dereferencing the clockdomain name string as a struct clockdomain
pointer.

Problem reported by Russell King <linux@....linux.org.uk>.

Tested on BeagleBoard ES2.1.

Signed-off-by: Paul Walmsley <paul@...an.com>
Cc: Russell King <linux@....linux.org.uk>.
---
 arch/arm/mach-omap2/clock.c |   21 ++++++++++-----------
 1 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/arch/arm/mach-omap2/clock.c b/arch/arm/mach-omap2/clock.c
index 600b2f4..53069cd 100644
--- a/arch/arm/mach-omap2/clock.c
+++ b/arch/arm/mach-omap2/clock.c
@@ -188,26 +188,32 @@ static int _dpll_test_fint(struct clk *clk, u8 n)
 }
 
 /**
- * omap2_init_clk_clkdm - look up a clockdomain name, store pointer in clk
+ * _omap2_init_clk_clkdm - look up a clockdomain name, store pointer in clk
  * @clk: OMAP clock struct ptr to use
  *
  * Convert a clockdomain name stored in a struct clk 'clk' into a
  * clockdomain pointer, and save it into the struct clk.  Intended to be
- * called during clk_register().  No return value.
+ * called during clk_register().  Returns 0 on success or -ENOENT if the
+ * clockdomain is not found.
  */
-void omap2_init_clk_clkdm(struct clk *clk)
+static int _omap2_init_clk_clkdm(struct clk *clk)
 {
 	struct clockdomain *clkdm;
+	int ret;
 
 	clkdm = clkdm_lookup(clk->clkdm.name);
 	if (clkdm) {
 		pr_debug("clock: associated clk %s to clkdm %s\n",
 			 clk->name, clk->clkdm.name);
 		clk->clkdm.ptr = clkdm;
+		ret = 0;
 	} else {
 		pr_err("clock: %s: could not associate to clkdm %s\n",
 		       clk->name, clk->clkdm.name);
+		ret = -ENOENT;
 	}
+
+	return ret;
 }
 
 /**
@@ -1082,12 +1088,5 @@ void omap2_clk_disable_unused(struct clk *clk)
 
 int omap2_clk_register(struct clk *clk)
 {
-	if (!clk->clkdm.name) {
-		pr_debug("clock: %s: missing clockdomain", clk->name);
-		WARN_ON(1);
-		return -EINVAL;
-	}
-
-	omap2_init_clk_clkdm(clk);
-	return 0;
+	return _omap2_init_clk_clkdm(clk);
 }
-- 
1.6.0.2.GIT

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