Re: [PATCH v2 1/2] watchdog: dw_wdt: No need for a spinlock

Guenter Roeck
2015-05-08T04:51:10Z

On 05/07/2015 09:27 PM, Doug Anderson wrote:
> Right now the dw_wdt uses a spinlock to protect dw_wdt_open(). The
> problem is that while holding the spinlock we call:
> -> dw_wdt_set_top()
> -> dw_wdt_top_in_seconds()
> -> clk_get_rate()
> -> clk_prepare_lock()
> -> mutex_lock()
>
> Locking a mutex while holding a spinlock is not allowed and leads to
> warnings like "BUG: spinlock wrong CPU on CPU#1", among other
> problems.
>
> There's no reason to use a spinlock. Only dw_wdt_open() was protected
> and the test_and_set_bit() at the start of that function protects us
> anyway.
>
> Signed-off-by: Doug Anderson <dianders@chromium.org>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>