linux-kernel - [PATCH 03/37] binder: Use wake up hint for synchronous transactions.

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Message-Id: <20170629190211.16927-4-tkjos@google.com>
Date:   Thu, 29 Jun 2017 12:01:37 -0700
From:   Todd Kjos <tkjos@...roid.com>
To:     gregkh@...uxfoundation.org, arve@...roid.com,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        maco@...gle.com, tkjos@...gle.com
Cc:     Riley Andrews <riandrews@...gle.com>,
        Omprakash Dhyade <odhyade@...eaurora.org>
Subject: [PATCH 03/37] binder: Use wake up hint for synchronous transactions.

From: Riley Andrews <riandrews@...gle.com>

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@...gle.com>
Signed-off-by: Omprakash Dhyade <odhyade@...eaurora.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:
-- 
2.13.2.725.g09c95d1e9-goog