The patch titled
Subject: include/linux/wait.h: fix clang -Wuninitialized warnings
has been added to the -mm tree. Its filename is
waitqueue-fix-clang-wuninitialized-warnings.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/waitqueue-fix-clang-wuninitialized-warnings.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/waitqueue-fix-clang-wuninitialized-warnings.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: include/linux/wait.h: fix clang -Wuninitialized warnings
When CONFIG_LOCKDEP is set, every use of DECLARE_WAIT_QUEUE_HEAD_ONSTACK()
produces an annoying 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; })
^~~~
After playing with it for a while, I have found a way to rephrase the
macro in a way that should work well with both gcc and clang and not
produce this warning. The open-coded __WAIT_QUEUE_HEAD_INIT_ONSTACK is a
little more verbose than the original version by Peter Zijlstra, but
avoids the gcc-ism that suppresses warnings when assigning a variable to
itself.
Link: http://lkml.kernel.org/r/20190703081119.209976-1-arnd@xxxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Tested-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/wait.h | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/include/linux/wait.h~waitqueue-fix-clang-wuninitialized-warnings
+++ a/include/linux/wait.h
@@ -68,8 +68,15 @@ extern void __init_waitqueue_head(struct
} while (0)
#ifdef CONFIG_LOCKDEP
-# define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
- ({ init_waitqueue_head(&name); name; })
+# define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) { \
+ .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
+ .head = ({ \
+ static struct lock_class_key __key; \
+ lockdep_set_class_and_name(&(name).lock, &__key, # name); \
+ (struct list_head){ &(name).head, &(name).head }; \
+ }), \
+}
+
# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
struct wait_queue_head name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
#else
_
Patches currently in -mm which might be from arnd@xxxxxxxx are
mm-sparse-fix-memory-leak-of-sparsemap_buf-in-aliged-memory-fix.patch
waitqueue-fix-clang-wuninitialized-warnings.patch
lib-test_meminit-fix-wmaybe-uninitialized-false-positive.patch
coda-stop-using-struct-timespec-in-user-api.patch
proc-sysctl-add-shared-variables-for-range-check-fix-3.patch
