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Subject[PATCH] [RFC v2] sched: make DECLARE_COMPLETION_ONSTACK() work with clang
Date
Building with clang, we get a warning for each use of COMPLETION_INITIALIZER_ONSTACK, e.g.:

block/blk-exec.c:103:29: warning: variable 'wait' is uninitialized when used within its own initialization [-Wuninitialized]
include/linux/completion.h:61:58: note: expanded from macro 'DECLARE_COMPLETION_ONSTACK'
include/linux/completion.h:34:29: note: expanded from macro 'COMPLETION_INITIALIZER_ONSTACK'

This seems to be a problem in clang, but it's relatively easy to work around
by changing the assignment.

I filed a bug against clang for the warning, but if we want to support old versions,
we may want this change as well.

I have not yet checked if the new version produces worse object code.

Link: https://llvm.org/bugs/show_bug.cgi?id=31829
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: send the correct patch
---
include/linux/completion.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/completion.h b/include/linux/completion.h
index 5d5aaae3af43..fa5d3efaba56 100644
--- a/include/linux/completion.h
+++ b/include/linux/completion.h
@@ -31,7 +31,7 @@ struct completion {
{ 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait) }

#define COMPLETION_INITIALIZER_ONSTACK(work) \
- ({ init_completion(&work); work; })
+ (*init_completion(&work))

/**
* DECLARE_COMPLETION - declare and initialize a completion structure
@@ -70,10 +70,11 @@ struct completion {
* This inline function will initialize a dynamically created completion
* structure.
*/
-static inline void init_completion(struct completion *x)
+static inline struct completion *init_completion(struct completion *x)
{
x->done = 0;
init_waitqueue_head(&x->wait);
+ return x;
}

/**
--
2.9.0
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