android: binder: Use wake up hint for synchronous transactions.

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

Change-Id: Ic406a232d0873662f80148e37acefe5243d912a0
Signed-off-by: Todd Kjos <tkjos@google.com>
Git-commit: 443c026e90820170aa3db2c21d2933ae5922f900
Git-repo: https://android.googlesource.com/kernel/msm
Signed-off-by: Omprakash Dhyade <odhyade@codeaurora.org>

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index f0ce995..93b410a 100644 (file)
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -1710,8 +1710,16 @@ 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)) {
+                       preempt_disable();
+                       wake_up_interruptible_sync(target_wait);
+                       sched_preempt_enable_no_resched();
+               }
+               else {
+                       wake_up_interruptible(target_wait);
+               }
+       }
        return;
 
 err_get_unused_fd_failed: