[PATCH 4.9 27/39] binder: add missing binder_unlock()

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@xxxxxxxxxx>

When commit 4be5a2810489 ("binder: check for binder_thread allocation
failure in binder_poll()") was applied to 4.4-stable and 4.9-stable it
was forgotten to release the global binder lock in the new error path.
The global binder lock wasn't removed until v4.14, by commit
a60b890f607d ("binder: remove global binder lock").

Fix the new error path to release the lock.

Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/android/binder.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2628,8 +2628,10 @@ static unsigned int binder_poll(struct f
 	binder_lock(__func__);
 
 	thread = binder_get_thread(proc);
-	if (!thread)
+	if (!thread) {
+		binder_unlock(__func__);
 		return POLLERR;
+	}
 
 	wait_for_proc_work = thread->transaction_stack == NULL &&
 		list_empty(&thread->todo) && thread->return_error == BR_OK;