summaryrefslogtreecommitdiff
path: root/arch/x86
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2014-01-20 10:23:08 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-20 10:23:08 -0800
commit6ffbe7d1fabddc768724656f159759cae7818cd9 (patch)
treeece184db0c35bcd9606968303984b430c24b847f /arch/x86
parent897aea303fec0c24b2a21b8e29f45dc73a234555 (diff)
parent63b1a81699c2a45c9f737419b1ec1da0ecf92812 (diff)
Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core locking changes from Ingo Molnar: - futex performance increases: larger hashes, smarter wakeups - mutex debugging improvements - lots of SMP ordering documentation updates - introduce the smp_load_acquire(), smp_store_release() primitives. (There are WIP patches that make use of them - not yet merged) - lockdep micro-optimizations - lockdep improvement: better cover IRQ contexts - liblockdep at last. We'll continue to monitor how useful this is * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits) futexes: Fix futex_hashsize initialization arch: Re-sort some Kbuild files to hopefully help avoid some conflicts futexes: Avoid taking the hb->lock if there's nothing to wake up futexes: Document multiprocessor ordering guarantees futexes: Increase hash table size for better performance futexes: Clean up various details arch: Introduce smp_load_acquire(), smp_store_release() arch: Clean up asm/barrier.h implementations using asm-generic/barrier.h arch: Move smp_mb__{before,after}_atomic_{inc,dec}.h into asm/atomic.h locking/doc: Rename LOCK/UNLOCK to ACQUIRE/RELEASE mutexes: Give more informative mutex warning in the !lock->owner case powerpc: Full barrier for smp_mb__after_unlock_lock() rcu: Apply smp_mb__after_unlock_lock() to preserve grace periods Documentation/memory-barriers.txt: Downgrade UNLOCK+BLOCK locking: Add an smp_mb__after_unlock_lock() for UNLOCK+BLOCK barrier Documentation/memory-barriers.txt: Document ACCESS_ONCE() Documentation/memory-barriers.txt: Prohibit speculative writes Documentation/memory-barriers.txt: Add long atomic examples to memory-barriers.txt Documentation/memory-barriers.txt: Add needed ACCESS_ONCE() calls to memory-barriers.txt Revert "smp/cpumask: Make CONFIG_CPUMASK_OFFSTACK=y usable without debug dependency" ...
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/barrier.h43
1 files changed, 42 insertions, 1 deletions
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index c6cd358a1eec..04a48903b2eb 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -92,12 +92,53 @@
#endif
#define smp_read_barrier_depends() read_barrier_depends()
#define set_mb(var, value) do { (void)xchg(&var, value); } while (0)
-#else
+#else /* !SMP */
#define smp_mb() barrier()
#define smp_rmb() barrier()
#define smp_wmb() barrier()
#define smp_read_barrier_depends() do { } while (0)
#define set_mb(var, value) do { var = value; barrier(); } while (0)
+#endif /* SMP */
+
+#if defined(CONFIG_X86_OOSTORE) || defined(CONFIG_X86_PPRO_FENCE)
+
+/*
+ * For either of these options x86 doesn't have a strong TSO memory
+ * model and we should fall back to full barriers.
+ */
+
+#define smp_store_release(p, v) \
+do { \
+ compiletime_assert_atomic_type(*p); \
+ smp_mb(); \
+ ACCESS_ONCE(*p) = (v); \
+} while (0)
+
+#define smp_load_acquire(p) \
+({ \
+ typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ compiletime_assert_atomic_type(*p); \
+ smp_mb(); \
+ ___p1; \
+})
+
+#else /* regular x86 TSO memory ordering */
+
+#define smp_store_release(p, v) \
+do { \
+ compiletime_assert_atomic_type(*p); \
+ barrier(); \
+ ACCESS_ONCE(*p) = (v); \
+} while (0)
+
+#define smp_load_acquire(p) \
+({ \
+ typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ compiletime_assert_atomic_type(*p); \
+ barrier(); \
+ ___p1; \
+})
+
#endif
/*