Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH] [v2] waitqueue: shut up clang -Wuninitialized warnings | Date | Fri, 19 Jul 2019 13:36:00 +0200 |
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When CONFIG_LOCKDEP is set, every use of DECLARE_WAIT_QUEUE_HEAD_ONSTACK() produces an bogus warning from clang, which is particularly annoying for allmodconfig builds:
fs/namei.c:1646:34: error: variable 'wq' is uninitialized when used within its own initialization [-Werror,-Wuninitialized] DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); ^~ include/linux/wait.h:74:63: note: expanded from macro 'DECLARE_WAIT_QUEUE_HEAD_ONSTACK' struct wait_queue_head name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) ~~~~ ^~~~ include/linux/wait.h:72:33: note: expanded from macro '__WAIT_QUEUE_HEAD_INIT_ONSTACK' ({ init_waitqueue_head(&name); name; }) ^~~~
A patch for clang has already been proposed and should soon be merged for clang-9, but for now all clang versions produce the warning in an otherwise (almost) clean allmodconfig build.
Link: https://bugs.llvm.org/show_bug.cgi?id=31829 Link: https://bugs.llvm.org/show_bug.cgi?id=42604 Link: https://lore.kernel.org/lkml/20190703081119.209976-1-arnd@arndb.de/ Link: https://reviews.llvm.org/D64678 Link: https://storage.kernelci.org/next/master/next-20190717/arm64/allmodconfig/clang-8/build-warnings.log Suggested-by: Nathan Chancellor <natechancellor@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- v2: given that kernelci is getting close to reporting a clean build for clang, I'm trying again with a less invasive approach after my first version was not too popular. --- include/linux/wait.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/include/linux/wait.h b/include/linux/wait.h index ddb959641709..276499ae1a3e 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -70,8 +70,17 @@ extern void __init_waitqueue_head(struct wait_queue_head *wq_head, const char *n #ifdef CONFIG_LOCKDEP # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \ ({ init_waitqueue_head(&name); name; }) -# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \ +# if defined(__clang__) && __clang_major__ <= 9 +/* work around https://bugs.llvm.org/show_bug.cgi?id=42604 */ +# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \ + _Pragma("clang diagnostic push") \ + _Pragma("clang diagnostic ignored \"-Wuninitialized\"") \ + struct wait_queue_head name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \ + _Pragma("clang diagnostic pop") +# else +# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \ struct wait_queue_head name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) +# endif #else # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name) #endif -- 2.20.0
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