patch "binder: Use wake up hint for synchronous transactions." added to char-misc-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    binder: Use wake up hint for synchronous transactions.

to my char-misc git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 00b40d613352c623aaae88a44e5ded7c912909d7 Mon Sep 17 00:00:00 2001
From: Riley Andrews <riandrews@google.com>
Date: Thu, 29 Jun 2017 12:01:37 -0700
Subject: binder: Use wake up hint for synchronous transactions.

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>
Cc: stable <stable@vger.kernel.org> # 4.4+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/android/binder.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 9393924ae8e8..f7665c31feca 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2200,8 +2200,12 @@ 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_translate_failed:
-- 
2.13.3