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sched: fix regression with sched yield

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Balbir Singh reported:

> 1:mon> t
> [c0000000e7677da0] c000000000067de0 .sys_sched_yield+0x6c/0xbc
> [c0000000e7677e30] c000000000008748 syscall_exit+0x0/0x40
> --- Exception: c01 (System Call) at 00000400001d09e4
> SP (4000664cb10) is in userspace
> 1:mon> r
> cpu 0x1: Vector: 300 (Data Access) at [c0000000e7677aa0]
>     pc: c000000000068e50: .yield_task_fair+0x94/0xc4
>     lr: c000000000067de0: .sys_sched_yield+0x6c/0xbc

the check that should have avoided that is:

        /*
         * Are we the only task in the tree?
         */
        if (unlikely(rq->load.weight == curr->se.load.weight))
                return;

But I guess that overlooks rt tasks, they also increase the load.
So I guess something like this ought to fix it..

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2008-02-18 13:39:37 +01:00 committed by Ingo Molnar
parent 19fb518c2a
commit 79b3feffb1
1 changed files with 1 additions and 1 deletions
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2
kernel/sched_fair.c
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@ -904,7 +904,7 @@ static void yield_task_fair(struct rq *rq)
/*
* Already in the rightmost position?
*/
if (unlikely(rightmost->vruntime < se->vruntime))
if (unlikely(!rightmost || rightmost->vruntime < se->vruntime))
return;
/*