From: Riley Andrews <riandrews@google.com>
Date: Thu, 29 Jun 2017 19:01:37 +0000 (-0700)
Subject: binder: Use wake up hint for synchronous transactions.
X-Git-Tag: v4.4.85~15
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=1792d6c17cb282fd8e5cd197a8b33cb78484eb6a;p=thirdparty%2Fkernel%2Fstable.git

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 76650faca2f6b..74da4821b8d68 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -1718,8 +1718,12 @@ 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: