This is a note to let you know that I've just added the patch titled
sched: Fix cross-sched-class wakeup preemption
to the 2.6.32-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.32.git;a=summary
The filename of the patch is:
0025-sched-Fix-cross-sched-class-wakeup-preemption.patch
and it can be found in the queue-2.6.32 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.32 longterm
tree,
please let <[email protected]> know about it.
>From 468c96415699ad8a02ed501eaa2f6f775ec3b87a Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <[email protected]>
Date: Thu, 10 Feb 2011 10:23:29 +0100
Subject: sched: Fix cross-sched-class wakeup preemption
Commit: 1e5a74059f9059d330744eac84873b1b99657008 upstream
Instead of dealing with sched classes inside each check_preempt_curr()
implementation, pull out this logic into the generic wakeup preemption
path.
This fixes a hang in KVM (and others) where we are waiting for the
stop machine thread to run ...
Reported-by: Markus Trippelsdorf <[email protected]>
Tested-by: Marcelo Tosatti <[email protected]>
Tested-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
LKML-Reference: <1288891946.2039.31.camel@laptop>
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Mike Galbraith <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/sched.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -594,11 +594,7 @@ struct rq {
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
-static inline
-void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
-{
- rq->curr->sched_class->check_preempt_curr(rq, p, flags);
-}
+static void check_preempt_curr(struct rq *rq, struct task_struct *p, int
flags);
static inline int cpu_of(struct rq *rq)
{
@@ -2392,6 +2388,24 @@ void task_oncpu_function_call(struct tas
preempt_enable();
}
+static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
+{
+ const struct sched_class *class;
+
+ if (p->sched_class == rq->curr->sched_class) {
+ rq->curr->sched_class->check_preempt_curr(rq, p, flags);
+ } else {
+ for_each_class(class) {
+ if (class == rq->curr->sched_class)
+ break;
+ if (class == p->sched_class) {
+ resched_task(rq->curr);
+ break;
+ }
+ }
+ }
+}
+
#ifdef CONFIG_SMP
/*
* ->cpus_allowed is protected by either TASK_WAKING or rq->lock held.
Patches currently in longterm-queue-2.6.32 which might be from
[email protected] are
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