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authorJonathan Corbet <corbet@lwn.net>2008-03-28 14:15:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-03-28 14:45:21 -0700
commit8c703d35fa91911dd92a18c31a718853f483ad80 (patch)
tree13b63c9754ad202cc7f4528ee94c7c54f3f88bba /include
parentf67e74ca690d9f168cc468b7d714caad492740a6 (diff)
in_atomic(): document why it is unsuitable for general use
Discourage people from inappropriately using in_atomic() Signed-off-by: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/hardirq.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 49829988bfa0..897f723bd222 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -72,6 +72,13 @@
#define in_softirq() (softirq_count())
#define in_interrupt() (irq_count())
+/*
+ * Are we running in atomic context? WARNING: this macro cannot
+ * always detect atomic context; in particular, it cannot know about
+ * held spinlocks in non-preemptible kernels. Thus it should not be
+ * used in the general case to determine whether sleeping is possible.
+ * Do not use in_atomic() in driver code.
+ */
#define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
#ifdef CONFIG_PREEMPT

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