| | Date | Sat, 18 Sep 2010 11:59:07 -0700 | | From | Greg KH <> | | Subject | [103/123] sched: Remove unnecessary RCU exclusion |
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From: Peter Zijlstra <a.p.zijlstra@chello.nl>
commit fb58bac5c75bfff8bbf7d02071a10a62f32fe28b upstream
As Nick pointed out, and realized by myself when doing: sched: Fix balance vs hotplug race the patch: sched: for_each_domain() vs RCU
is wrong, sched_domains are freed after synchronize_sched(), which means disabling preemption is enough.
Reported-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- kernel/sched_fair.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1410,7 +1410,6 @@ select_task_rq_fair(struct rq *rq, struc new_cpu = prev_cpu; } - rcu_read_lock(); for_each_domain(cpu, tmp) { if (!(tmp->flags & SD_LOAD_BALANCE)) continue; @@ -1500,10 +1499,8 @@ select_task_rq_fair(struct rq *rq, struc } } - if (affine_sd && wake_affine(affine_sd, p, sync)) { - new_cpu = cpu; - goto out; - } + if (affine_sd && wake_affine(affine_sd, p, sync)) + return cpu; while (sd) { int load_idx = sd->forkexec_idx; @@ -1544,8 +1541,6 @@ select_task_rq_fair(struct rq *rq, struc /* while loop will break here if sd == NULL */ } -out: - rcu_read_unlock(); return new_cpu; } #endif /* CONFIG_SMP */
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