[B,01/10] OMAP2/3 clock: combine clkdm, clkdm_name into union in struct clk

Commit Message

Paul Walmsley Feb. 4, 2009, 10:47 p.m. UTC

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 <[e-mail]>
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 <[e-mail]>.

Tested on BeagleBoard ES2.1.

Signed-off-by: Paul Walmsley <[e-mail]>
Cc: Russell King <[e-mail]>.
---
 arch/arm/mach-omap2/clock.c |   21 ++++++++++-----------
 1 files changed, 10 insertions(+), 11 deletions(-)

Patch

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);
 }