From 72dec758064322ed674749ca38478c7ce08fe31b Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <arjan@linux.intel.com>
Date: Mon, 1 Sep 2008 15:52:40 -0700
Subject: [PATCH] --- yaml --- r: 117608 b: refs/heads/master c:
 6976675d94042fbd446231d1bd8b7de71a980ada h: refs/heads/master v: v3

---
 [refs]                          |  2 +-
 trunk/include/linux/init_task.h |  1 +
 trunk/include/linux/prctl.h     |  7 +++++++
 trunk/include/linux/sched.h     |  6 ++++++
 trunk/kernel/fork.c             |  2 ++
 trunk/kernel/sys.c              | 10 ++++++++++
 6 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index acc96e4063ae..071bd3a7bd96 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 654c8e0b1c623b156c5b92f28d914ab38c9c2c90
+refs/heads/master: 6976675d94042fbd446231d1bd8b7de71a980ada
diff --git a/trunk/include/linux/init_task.h b/trunk/include/linux/init_task.h
index 021d8e720c79..23fd8909b9e5 100644
--- a/trunk/include/linux/init_task.h
+++ b/trunk/include/linux/init_task.h
@@ -170,6 +170,7 @@ extern struct group_info init_groups;
 	.cpu_timers	= INIT_CPU_TIMERS(tsk.cpu_timers),		\
 	.fs_excl	= ATOMIC_INIT(0),				\
 	.pi_lock	= __SPIN_LOCK_UNLOCKED(tsk.pi_lock),		\
+	.timer_slack_ns = 50000, /* 50 usec default slack */		\
 	.pids = {							\
 		[PIDTYPE_PID]  = INIT_PID_LINK(PIDTYPE_PID),		\
 		[PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID),		\
diff --git a/trunk/include/linux/prctl.h b/trunk/include/linux/prctl.h
index 5ad79198d6f9..48d887e3c6e7 100644
--- a/trunk/include/linux/prctl.h
+++ b/trunk/include/linux/prctl.h
@@ -78,4 +78,11 @@
 #define PR_GET_SECUREBITS 27
 #define PR_SET_SECUREBITS 28
 
+/*
+ * Get/set the timerslack as used by poll/select/nanosleep
+ * A value of 0 means "use default"
+ */
+#define PR_SET_TIMERSLACK 29
+#define PR_GET_TIMERSLACK 30
+
 #endif /* _LINUX_PRCTL_H */
diff --git a/trunk/include/linux/sched.h b/trunk/include/linux/sched.h
index 3d9120c5ad15..dcc03fd5a7f3 100644
--- a/trunk/include/linux/sched.h
+++ b/trunk/include/linux/sched.h
@@ -1301,6 +1301,12 @@ struct task_struct {
 	int latency_record_count;
 	struct latency_record latency_record[LT_SAVECOUNT];
 #endif
+	/*
+	 * time slack values; these are used to round up poll() and
+	 * select() etc timeout values. These are in nanoseconds.
+	 */
+	unsigned long timer_slack_ns;
+	unsigned long default_timer_slack_ns;
 };
 
 /*
diff --git a/trunk/kernel/fork.c b/trunk/kernel/fork.c
index 7ce2ebe84796..4308d75f0fa5 100644
--- a/trunk/kernel/fork.c
+++ b/trunk/kernel/fork.c
@@ -987,6 +987,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	p->prev_utime = cputime_zero;
 	p->prev_stime = cputime_zero;
 
+	p->default_timer_slack_ns = current->timer_slack_ns;
+
 #ifdef CONFIG_DETECT_SOFTLOCKUP
 	p->last_switch_count = 0;
 	p->last_switch_timestamp = 0;
diff --git a/trunk/kernel/sys.c b/trunk/kernel/sys.c
index 038a7bc0901d..1b96401a0576 100644
--- a/trunk/kernel/sys.c
+++ b/trunk/kernel/sys.c
@@ -1727,6 +1727,16 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
 		case PR_SET_TSC:
 			error = SET_TSC_CTL(arg2);
 			break;
+		case PR_GET_TIMERSLACK:
+			error = current->timer_slack_ns;
+			break;
+		case PR_SET_TIMERSLACK:
+			if (arg2 <= 0)
+				current->timer_slack_ns =
+					current->default_timer_slack_ns;
+			else
+				current->timer_slack_ns = arg2;
+			break;
 		default:
 			error = -EINVAL;
 			break;