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| author | Will Deacon <will.deacon@arm.com> | 2017-10-24 11:22:47 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-10-24 13:17:32 +0200 |
| commit | 76ebbe78f7390aee075a7f3768af197ded1bdfbb (patch) | |
| tree | 531d3794d965b8e4e8107d8dbd1b124cbf3dbca5 /include/linux/compiler.h | |
| parent | d15155824c5014803d91b829736d249c500bdda6 (diff) | |
| download | lwn-76ebbe78f7390aee075a7f3768af197ded1bdfbb.tar.gz lwn-76ebbe78f7390aee075a7f3768af197ded1bdfbb.zip | |
locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE()
In preparation for the removal of lockless_dereference(), which is the
same as READ_ONCE() on all architectures other than Alpha, add an
implicit smp_read_barrier_depends() to READ_ONCE() so that it can be
used to head dependency chains on all architectures.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-3-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/compiler.h')
| -rw-r--r-- | include/linux/compiler.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 08083186e54f..7d7b77da9716 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -242,6 +242,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s __read_once_size(&(x), __u.__c, sizeof(x)); \ else \ __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ + smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ __u.__val; \ }) #define READ_ONCE(x) __READ_ONCE(x, 1) |