linux-kernel - [git pull] scheduler fixes

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Date:	Thu, 12 Jun 2008 21:18:48 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [git pull] scheduler fixes


Linus,

please pull the latest scheduler fixes git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git sched-fixes-for-linus

thanks,

	Ingo

------------------>
Lai Jiangshan (2):
      sched: fair group: fix overflow(was: fix divide by zero)
      sched: 64-bit: fix arithmetics overflow

Oleg Nesterov (1):
      sched: fix TASK_WAKEKILL vs SIGKILL race

 include/linux/sched.h |   13 +++++++++++++
 kernel/sched.c        |   22 ++++++++++++++--------
 2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index ae0be3c..c5d3f84 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2026,6 +2026,19 @@ static inline int fatal_signal_pending(struct task_struct *p)
 	return signal_pending(p) && __fatal_signal_pending(p);
 }
 
+static inline int signal_pending_state(long state, struct task_struct *p)
+{
+	if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
+		return 0;
+	if (!signal_pending(p))
+		return 0;
+
+	if (state & (__TASK_STOPPED | __TASK_TRACED))
+		return 0;
+
+	return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
+}
+
 static inline int need_resched(void)
 {
 	return unlikely(test_thread_flag(TIF_NEED_RESCHED));
diff --git a/kernel/sched.c b/kernel/sched.c
index bfb8ad8..eaf6751 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -312,12 +312,15 @@ static DEFINE_SPINLOCK(task_group_lock);
 #endif
 
 /*
- * A weight of 0, 1 or ULONG_MAX can cause arithmetics problems.
+ * A weight of 0 or 1 can cause arithmetics problems.
+ * A weight of a cfs_rq is the sum of weights of which entities
+ * are queued on this cfs_rq, so a weight of a entity should not be
+ * too large, so as the shares value of a task group.
  * (The default weight is 1024 - so there's no practical
  *  limitation from this.)
  */
 #define MIN_SHARES	2
-#define MAX_SHARES	(ULONG_MAX - 1)
+#define MAX_SHARES	(1UL << 18)
 
 static int init_task_group_load = INIT_TASK_GROUP_LOAD;
 #endif
@@ -1337,8 +1340,13 @@ calc_delta_mine(unsigned long delta_exec, unsigned long weight,
 {
 	u64 tmp;
 
-	if (!lw->inv_weight)
-		lw->inv_weight = 1 + (WMULT_CONST-lw->weight/2)/(lw->weight+1);
+	if (!lw->inv_weight) {
+		if (BITS_PER_LONG > 32 && unlikely(lw->weight >= WMULT_CONST))
+			lw->inv_weight = 1;
+		else
+			lw->inv_weight = 1 + (WMULT_CONST-lw->weight/2)
+				/ (lw->weight+1);
+	}
 
 	tmp = (u64)delta_exec * weight;
 	/*
@@ -4159,12 +4167,10 @@ need_resched_nonpreemptible:
 	clear_tsk_need_resched(prev);
 
 	if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
-		if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
-				signal_pending(prev))) {
+		if (unlikely(signal_pending_state(prev->state, prev)))
 			prev->state = TASK_RUNNING;
-		} else {
+		else
 			deactivate_task(rq, prev, 1);
-		}
 		switch_count = &prev->nvcsw;
 	}
 
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