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authorPeter Zijlstra <peterz@infradead.org>2014-04-19 02:07:17 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-19 03:40:08 +0400
commit8b32201de1f87878ace971bfdc2846a4f3a5bb2b (patch)
tree7f9bf1d69e618d47591786b1e39262251eba5119 /include/linux/wait.h
parent9cc236827fde5e254fd995a0023c05c5ee3a3ba6 (diff)
downloadlinux-8b32201de1f87878ace971bfdc2846a4f3a5bb2b.tar.xz
wait: explain the shadowing and type inconsistencies
Stick in a comment before someone else tries to fix the sparse warning this generates. Suggested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-o2ro6f3vkxklni0bc8f7m68s@git.kernel.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/wait.h')
-rw-r--r--include/linux/wait.h14
1 files changed, 13 insertions, 1 deletions
diff --git a/include/linux/wait.h b/include/linux/wait.h
index e7d9d9ed14f5..bd68819f0815 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -191,11 +191,23 @@ wait_queue_head_t *bit_waitqueue(void *, int);
(!__builtin_constant_p(state) || \
state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE) \
+/*
+ * The below macro ___wait_event() has an explicit shadow of the __ret
+ * variable when used from the wait_event_*() macros.
+ *
+ * This is so that both can use the ___wait_cond_timeout() construct
+ * to wrap the condition.
+ *
+ * The type inconsistency of the wait_event_*() __ret variable is also
+ * on purpose; we use long where we can return timeout values and int
+ * otherwise.
+ */
+
#define ___wait_event(wq, condition, state, exclusive, ret, cmd) \
({ \
__label__ __out; \
wait_queue_t __wait; \
- long __ret = ret; \
+ long __ret = ret; /* explicit shadow */ \
\
INIT_LIST_HEAD(&__wait.task_list); \
if (exclusive) \