Merge commit 'v2.6.34-rc2' into perf/core

Merge reason: Pick up latest perf fixes from upstream.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 16 insertions, 10 deletions

diff --git a/net/tipc/ref.c b/net/tipc/ref.c
index 414fc34b8bea..8dea66500cf5 100644
--- a/net/tipc/ref.c
+++ b/net/tipc/ref.c
@@ -153,11 +153,11 @@ void tipc_ref_table_stop(void)
 
 u32 tipc_ref_acquire(void *object, spinlock_t **lock)
 {
-	struct reference *entry;
 	u32 index;
 	u32 index_mask;
 	u32 next_plus_upper;
 	u32 ref;
+	struct reference *entry = NULL;
 
 	if (!object) {
 		err("Attempt to acquire reference to non-existent object\n");
@@ -175,30 +175,36 @@ u32 tipc_ref_acquire(void *object, spinlock_t **lock)
 		index = tipc_ref_table.first_free;
 		entry = &(tipc_ref_table.entries[index]);
 		index_mask = tipc_ref_table.index_mask;
-		/* take lock in case a previous user of entry still holds it */
-		spin_lock_bh(&entry->lock);
 		next_plus_upper = entry->ref;
 		tipc_ref_table.first_free = next_plus_upper & index_mask;
 		ref = (next_plus_upper & ~index_mask) + index;
-		entry->ref = ref;
-		entry->object = object;
-		*lock = &entry->lock;
 	}
 	else if (tipc_ref_table.init_point < tipc_ref_table.capacity) {
 		index = tipc_ref_table.init_point++;
 		entry = &(tipc_ref_table.entries[index]);
 		spin_lock_init(&entry->lock);
-		spin_lock_bh(&entry->lock);
 		ref = tipc_ref_table.start_mask + index;
-		entry->ref = ref;
-		entry->object = object;
-		*lock = &entry->lock;
 	}
 	else {
 		ref = 0;
 	}
 	write_unlock_bh(&ref_table_lock);
 
+	/*
+	 * Grab the lock so no one else can modify this entry
+	 * While we assign its ref value & object pointer
+	 */
+	if (entry) {
+		spin_lock_bh(&entry->lock);
+		entry->ref = ref;
+		entry->object = object;
+		*lock = &entry->lock;
+		/*
+		 * keep it locked, the caller is responsible
+		 * for unlocking this when they're done with it
+		 */
+	}
+
 	return ref;
 }