Re: [PATCH] cbus-tahvo: Add tahvo_write_reg locking

Felipe Balbi
2011-11-07T06:10:50Z

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Hi,

On Sat, Nov 05, 2011 at 05:19:54PM +0100, Michael Büsch wrote:
> tahvo_write_reg() needs to take the mutex to avoid a race
> condition with tahvo_set_clear_reg_bits:
>
> tahvo_set_clear_reg_bits(): | tahvo_write_reg():
> __tahvo_read_reg() |
> | __tahvo_write_reg() <-- race here
> __tahvo_write_reg() |
>
> Signed-off-by: Michael Buesch <m@bues.ch>
>
> ---
>
> Index: linux-3.1/drivers/cbus/tahvo.c
> ===================================================================
> --- linux-3.1.orig/drivers/cbus/tahvo.c 2011-11-05 17:03:39.598846119 +0100
> +++ linux-3.1/drivers/cbus/tahvo.c 2011-11-05 17:04:36.274768324 +0100
> @@ -104,7 +104,9 @@ void tahvo_write_reg(struct device *chil
> {
> struct tahvo *tahvo = dev_get_drvdata(child->parent);
>
> + mutex_lock(&tahvo->mutex);
> __tahvo_write_reg(tahvo, reg, val);
> + mutex_unlock(&tahvo->mutex);

yeah, my bad. The same should be done with tahvo_read_reg(). Care to
resend this patch adding the change to tahvo_read_reg() too...

--
balbi

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