Re: use of preempt_count instead of in_atomic() at leds-gpio.c
From: Jonathan Corbet
Date: Mon Mar 24 2008 - 15:34:59 EST
Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> There's also a section about in_atomic() in the Linux Device Drivers
> (3rd ed.) book which may have contributed to the confusion.
My fault (again). Obviously it *looked* like something people could use
to me...
How about the following patch as a short-term penance to keep others
from making the same mistake?
jon
--
Discourage people from using in_atomic()
Signed-off-by: Jonathan Corbet <corbet@xxxxxxx>
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)
#ifdef CONFIG_PREEMPT
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/