Commit-ID: 27e4f9d0012a9bb7011aade862f08679d2921ab0
Gitweb: http://git.kernel.org/tip/27e4f9d0012a9bb7011aade862f08679d2921ab0
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 9 Apr 2014 12:50:34 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 18 Apr 2014 12:07:22 +0200
sched/wait: Explain the shadowing and type inconsistencies
Stick in a comment before someone else tries to fix the sparse warning
this generates.
Requested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-o2ro6f3vkxklni0bc8f7m68s@xxxxxxxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/wait.h | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 559044c..2b563a1 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) \
--
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