From e0fce87ac342cc89c2286044a02ba5cb723055b6 Mon Sep 17 00:00:00 2001
From: Riley Andrews <riandrews@google.com>
Date: Tue, 1 Sep 2015 12:42:07 -0700
Subject: [PATCH] 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
---
drivers/staging/android/binder.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c
index 0872499406cf..d3243164ea63 100644
--- a/drivers/staging/android/binder.c
+++ b/drivers/staging/android/binder.c
@@ -1687,8 +1687,16 @@ 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:
--
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