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 the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: binder-use-wake-up-hint-for-synchronous-transactions.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 00b40d613352c623aaae88a44e5ded7c912909d7 Mon Sep 17 00:00:00 2001 From: Riley Andrews <riandrews@xxxxxxxxxx> Date: Thu, 29 Jun 2017 12:01:37 -0700 Subject: binder: Use wake up hint for synchronous transactions. From: Riley Andrews <riandrews@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Omprakash Dhyade <odhyade@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/android/binder.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1718,8 +1718,12 @@ static void binder_transaction(struct bi 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: Patches currently in stable-queue which might be from riandrews@xxxxxxxxxx are queue-4.4/binder-use-wake-up-hint-for-synchronous-transactions.patch