Messages in this thread | | | Date | Mon, 24 Mar 2008 12:42:29 -0700 | From | Andrew Morton <> | Subject | Re: use of preempt_count instead of in_atomic() at leds-gpio.c |
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On Mon, 24 Mar 2008 13:34:49 -0600 corbet@lwn.net (Jonathan Corbet) wrote:
> Discourage people from using in_atomic() > > Signed-off-by: Jonathan Corbet <corbet@lwn.net> > > diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h > index 4982998..3d196cb 100644 > --- a/include/linux/hardirq.h > +++ b/include/linux/hardirq.h > @@ -72,6 +72,11 @@ > #define in_softirq() (softirq_count()) > #define in_interrupt() (irq_count()) > > +/* > + * Are we running in atomic context? WARNING: this macro cannot > + * always detect atomic context and should not be used to determine > + * whether sleeping is possible. Do not use it in driver code. > + */ > #define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
It'd be better if the comment were to describe _why_ in_atomic() is unreliable. ie: "does not account for held spinlocks on non-preemptible kernels".
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