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authorLinus Torvalds <torvalds@linux-foundation.org>2013-02-19 17:45:20 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-19 17:45:20 -0800
commite84cf5d0fd53badf3a93c790e280cc92a69ed999 (patch)
treeabc4d04bc31e5682794d1ea90c38cfeb4d5c9b97 /Documentation
parent19f949f52599ba7c3f67a5897ac6be14bfcb1200 (diff)
parentac0e32024b8f40987b3db7d2defdc6b5153ba354 (diff)
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU changes from Ingo Molnar: "SRCU changes: - These include debugging aids, updates that move towards the goal of permitting srcu_read_lock() and srcu_read_unlock() to be used from idle and offline CPUs, and a few small fixes. Changes to rcutorture and to RCU documentation: - Posted to LKML at https://lkml.org/lkml/2013/1/26/188 Enhancements to uniprocessor handling in tiny RCU: - Posted to LKML at https://lkml.org/lkml/2013/1/27/2 Tag RCU callbacks with grace-period number to simplify callback advancement: - Posted to LKML at https://lkml.org/lkml/2013/1/26/203 Miscellaneous fixes: - Posted to LKML at https://lkml.org/lkml/2013/1/26/204" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) srcu: use ACCESS_ONCE() to access sp->completed in srcu_read_lock() srcu: Update synchronize_srcu_expedited()'s comments srcu: Update synchronize_srcu()'s comments srcu: Remove checks preventing idle CPUs from calling srcu_read_lock() srcu: Remove checks preventing offline CPUs from calling srcu_read_lock() srcu: Simple cleanup for cleanup_srcu_struct() srcu: Add might_sleep() annotation to synchronize_srcu() srcu: Simplify __srcu_read_unlock() via this_cpu_dec() rcu: Allow rcutorture to be built at low optimization levels rcu: Make rcutorture's shuffler task shuffle recently added tasks rcu: Allow TREE_PREEMPT_RCU on UP systems rcu: Provide RCU CPU stall warnings for tiny RCU context_tracking: Add comments on interface and internals rcu: Remove obsolete Kconfig option from comment rcu: Remove unused code originally used for context tracking rcu: Consolidate debugging Kconfig options rcu: Correct 'optimized' to 'optimize' in header comment rcu: Trace callback acceleration rcu: Tag callback lists with corresponding grace-period number rcutorture: Don't compare ptr with 0 ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/atomic_ops.txt2
-rw-r--r--Documentation/memory-barriers.txt1
2 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/atomic_ops.txt b/Documentation/atomic_ops.txt
index 27f2b21a9d5..d9ca5be9b47 100644
--- a/Documentation/atomic_ops.txt
+++ b/Documentation/atomic_ops.txt
@@ -253,6 +253,8 @@ This performs an atomic exchange operation on the atomic variable v, setting
the given new value. It returns the old value that the atomic variable v had
just before the operation.
+atomic_xchg requires explicit memory barriers around the operation.
+
int atomic_cmpxchg(atomic_t *v, int old, int new);
This performs an atomic compare exchange operation on the atomic value v,
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index 3c4e1b3b80a..fa5d8a9ae20 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -1685,6 +1685,7 @@ explicit lock operations, described later). These include:
xchg();
cmpxchg();
+ atomic_xchg();
atomic_cmpxchg();
atomic_inc_return();
atomic_dec_return();