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

From: Guenter Roeck
Date: Fri May 08 2015 - 00:51:13 EST

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

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

Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

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