binder: Use wake up hint for synchronous transactions.

commit 00b40d613352c623aaae88a44e5ded7c912909d7 upstream.

Use wake_up_interruptible_sync() to hint to the scheduler binder
transactions are synchronous wakeups. Disable preemption while waking
to avoid ping-ponging on the binder lock.

Signed-off-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Omprakash Dhyade <odhyade@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index abd10af..5ce7ee9 100644 (file)
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -1724,8 +1724,12 @@ static void binder_transaction(struct binder_proc *proc,
        list_add_tail(&t->work.entry, target_list);
        tcomplete->type = BINDER_WORK_TRANSACTION_COMPLETE;
        list_add_tail(&tcomplete->entry, &thread->todo);
-       if (target_wait)
-               wake_up_interruptible(target_wait);
+       if (target_wait) {
+               if (reply || !(t->flags & TF_ONE_WAY))
+                       wake_up_interruptible_sync(target_wait);
+               else
+                       wake_up_interruptible(target_wait);
+       }
        return;
 
 err_get_unused_fd_failed: