diff options
| author | Boqun Feng <boqun.feng@gmail.com> | 2015-08-26 19:52:46 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-09-13 10:35:46 +0200 |
| commit | 84567995612258c23bc55795575babe7ef605dd9 (patch) | |
| tree | 69ae01847597ccd3e759b87dc5d11b457839298f /Documentation | |
| parent | c7ef92cea98bc468bbc8e67b6e49d7365dc69482 (diff) | |
locking/atomics, cmpxchg: Privatize the inclusion of asm/cmpxchg.h
After commit:
654672d4ba1a ("locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations")
Architectures may only provide {cmp,}xchg_relaxed definitions in
asm/cmpxchg.h. Other variants, such as {cmp,}xchg, may be built in
linux/atomic.h, which means simply including asm/cmpxchg.h may not get
the definitions of all the{cmp,}xchg variants.
Therefore, we should privatize the inclusions of asm/cmpxchg.h to
keep it only included in arch/* and replace the inclusions outside
with linux/atomic.h
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aybuke Ozdemir <aybuke.147@gmail.com>
Cc: Chris Brannon <chris@the-brannons.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirk Reiser <kirk@reisers.ca>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Shradha Shah <sshah@solarflare.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: William Hubbs <w.d.hubbs@gmail.com>
Cc: devel@driverdev.osuosl.org
Cc: linux-net-drivers@solarflare.com
Cc: speakup@linux-speakup.org
Link: http://lkml.kernel.org/r/1440589966-26280-1-git-send-email-boqun.feng@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/atomic_ops.txt | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/atomic_ops.txt b/Documentation/atomic_ops.txt index b19fc34efdb1..c9d1cacb4395 100644 --- a/Documentation/atomic_ops.txt +++ b/Documentation/atomic_ops.txt @@ -542,6 +542,10 @@ The routines xchg() and cmpxchg() must provide the same exact memory-barrier semantics as the atomic and bit operations returning values. +Note: If someone wants to use xchg(), cmpxchg() and their variants, +linux/atomic.h should be included rather than asm/cmpxchg.h, unless +the code is in arch/* and can take care of itself. + Spinlocks and rwlocks have memory barrier expectations as well. The rule to follow is simple: |