[PATCH 1/1] arm: mxc: utilise usecount field in clock operations
Amit Kucheria
amit.kucheria at verdurent.com
Fri May 28 04:29:09 EDT 2010
On 10 Apr 22, Tim Gardner wrote:
> On 04/22/2010 02:30 PM, Amit Kucheria wrote:
> >From: Amit Kucheria<amit.kucheria at canonical.com>
> >
> >This patch fixes the clock refcounting when reparenting is used.
> >
> >Sascha just pointed out a good explanation of refcounting here:
> >http://www.spinics.net/lists/arm-kernel/msg85879.html
> >
> >Signed-off-by: Amit Kucheria<amit.kucheria at canonical.com>
> >---
> > arch/arm/plat-mxc/clock.c | 34 ++++++++++++++++++++++------------
> > 1 files changed, 22 insertions(+), 12 deletions(-)
> >
> >diff --git a/arch/arm/plat-mxc/clock.c b/arch/arm/plat-mxc/clock.c
> >index 323ff8c..14781cc 100644
> >--- a/arch/arm/plat-mxc/clock.c
> >+++ b/arch/arm/plat-mxc/clock.c
> >@@ -50,15 +50,16 @@ static DEFINE_MUTEX(clocks_mutex);
> >
> > static void __clk_disable(struct clk *clk)
> > {
> >- if (clk == NULL || IS_ERR(clk))
> >+ WARN_ON(!clk->usecount);
> >+ if (clk == NULL || IS_ERR(clk) || !clk->usecount)
> > return;
> >
>
> The clk==NULL check seem superfluous if WARN_ON(!clk->usecount) has
> already dereferenced clk (and possibly crashed). You might need two
> statements if its likely that clk could be NULL.
>
Tim, You're right.
Sascha, updated patch to fix that issue and correspond more closely to
Russell's explanation follows.
Cheers,
Amit
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