[PATCH 05/97] sched: Fix task_hot() test order

[Greg Kroah-Hartman]

From: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>

commit e6c8fba7771563b2f3dfb96a78f36ec17e15bdf0 upstream.

Make sure not to access sched_fair fields before verifying it is
indeed a sched_fair task.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
LKML-Reference: <20091216170517.577998058@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 kernel/sched.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index d079a9f..2797859 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2036,6 +2036,9 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
 {
 	s64 delta;
 
+	if (p->sched_class != &fair_sched_class)
+		return 0;
+
 	/*
 	 * Buddy candidates are cache hot:
 	 */
@@ -2044,9 +2047,6 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
 			 &p->se == cfs_rq_of(&p->se)->last))
 		return 1;
 
-	if (p->sched_class != &fair_sched_class)
-		return 0;
-
 	if (sysctl_sched_migration_cost == -1)
 		return 1;
 	if (sysctl_sched_migration_cost == 0)
-- 
1.6.6

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