Merge tag 'v4.3-rc1' into locking/core, to refresh the tree

Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 14 insertions, 2 deletions

diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index 36942047ffc0..8e96f6cc2a4a 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -1,5 +1,5 @@
 
-obj-y += mutex.o semaphore.o rwsem.o
+obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o
 
 ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_lockdep.o = $(CC_FLAGS_FTRACE)
@@ -24,6 +24,5 @@ obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
 obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
 obj-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
 obj-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem-xadd.o
-obj-$(CONFIG_PERCPU_RWSEM) += percpu-rwsem.o
 obj-$(CONFIG_QUEUED_RWLOCKS) += qrwlock.o
 obj-$(CONFIG_LOCK_TORTURE_TEST) += locktorture.o
diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c
index 652a8ee8efe9..f32567254867 100644
--- a/kernel/locking/percpu-rwsem.c
+++ b/kernel/locking/percpu-rwsem.c
@@ -88,6 +88,19 @@ void percpu_down_read(struct percpu_rw_semaphore *brw)
         __up_read(&brw->rw_sem);
 }
 
+int percpu_down_read_trylock(struct percpu_rw_semaphore *brw)
+{
+        if (unlikely(!update_fast_ctr(brw, +1))) {
+                if (!__down_read_trylock(&brw->rw_sem))
+                        return 0;
+                atomic_inc(&brw->slow_read_ctr);
+                __up_read(&brw->rw_sem);
+        }
+
+        rwsem_acquire_read(&brw->rw_sem.dep_map, 0, 1, _RET_IP_);
+        return 1;
+}
+
 void percpu_up_read(struct percpu_rw_semaphore *brw)
 {
         rwsem_release(&brw->rw_sem.dep_map, 1, _RET_IP_);