Merge branch 'locking-rwsem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull support for killable rwsems from Ingo Molnar:
 "This, by Michal Hocko, implements down_write_killable().

  The main usecase will be to update mm_sem usage sites to use this new
  API, to allow the mm-reaper introduced in commit aac453635549 ("mm,
  oom: introduce oom reaper") to tear down oom victim address spaces
  asynchronously with minimum latencies and without deadlock worries"

[ The vfs will want it too as the inode lock is changed from a mutex to
  a rwsem due to the parallel lookup and readdir updates ]

* 'locking-rwsem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/rwsem: Fix comment on register clobbering
  locking/rwsem: Fix down_write_killable()
  locking/rwsem, x86: Add frame annotation for call_rwsem_down_write_failed_killable()
  locking/rwsem: Provide down_write_killable()
  locking/rwsem, x86: Provide __down_write_killable()
  locking/rwsem, s390: Provide __down_write_killable()
  locking/rwsem, ia64: Provide __down_write_killable()
  locking/rwsem, alpha: Provide __down_write_killable()
  locking/rwsem: Introduce basis for down_write_killable()
  locking/rwsem, sparc: Drop superfluous arch specific implementation
  locking/rwsem, sh: Drop superfluous arch specific implementation
  locking/rwsem, xtensa: Drop superfluous arch specific implementation
  locking/rwsem: Drop explicit memory barriers
  locking/rwsem: Get rid of __down_write_nested()

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index d10ef06971b5..f75222ea7f16 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -446,6 +446,18 @@ do {								\
         lock_acquired(&(_lock)->dep_map, _RET_IP_);                     \
 } while (0)
 
+#define LOCK_CONTENDED_RETURN(_lock, try, lock)                 \
+({                                                              \
+        int ____err = 0;                                        \
+        if (!try(_lock)) {                                      \
+                lock_contended(&(_lock)->dep_map, _RET_IP_);    \
+                ____err = lock(_lock);                          \
+        }                                                       \
+        if (!____err)                                           \
+                lock_acquired(&(_lock)->dep_map, _RET_IP_);     \
+        ____err;                                                \
+})
+
 #else /* CONFIG_LOCK_STAT */
 
 #define lock_contended(lockdep_map, ip) do {} while (0)
@@ -454,6 +466,9 @@ do {								\
 #define LOCK_CONTENDED(_lock, try, lock) \
         lock(_lock)
 
+#define LOCK_CONTENDED_RETURN(_lock, try, lock) \
+        lock(_lock)
+
 #endif /* CONFIG_LOCK_STAT */
 
 #ifdef CONFIG_LOCKDEP