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sched: fix missing locking in sched_domains code
Concurrent calls to detach_destroy_domains and arch_init_sched_domains were prevented by the old scheduler subsystem cpu hotplug mutex. When this got converted to get_online_cpus() the locking got broken. Unlike before now several processes can concurrently enter the critical sections that were protected by the old lock. So use the already present doms_cur_mutex to protect these sections again. Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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parent
690229a091
commit
712555ee4f
1 changed files with 12 additions and 17 deletions
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@ -242,6 +242,12 @@ static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
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}
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#endif
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/*
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* sched_domains_mutex serializes calls to arch_init_sched_domains,
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* detach_destroy_domains and partition_sched_domains.
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*/
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static DEFINE_MUTEX(sched_domains_mutex);
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#ifdef CONFIG_GROUP_SCHED
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#include <linux/cgroup.h>
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@ -308,9 +314,6 @@ static DEFINE_PER_CPU(struct rt_rq, init_rt_rq) ____cacheline_aligned_in_smp;
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*/
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static DEFINE_SPINLOCK(task_group_lock);
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/* doms_cur_mutex serializes access to doms_cur[] array */
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static DEFINE_MUTEX(doms_cur_mutex);
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#ifdef CONFIG_FAIR_GROUP_SCHED
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#ifdef CONFIG_USER_SCHED
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# define INIT_TASK_GROUP_LOAD (2*NICE_0_LOAD)
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@ -358,21 +361,9 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
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#endif
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}
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static inline void lock_doms_cur(void)
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{
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mutex_lock(&doms_cur_mutex);
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}
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static inline void unlock_doms_cur(void)
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{
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mutex_unlock(&doms_cur_mutex);
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}
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#else
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static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
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static inline void lock_doms_cur(void) { }
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static inline void unlock_doms_cur(void) { }
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#endif /* CONFIG_GROUP_SCHED */
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@ -7822,7 +7813,7 @@ void partition_sched_domains(int ndoms_new, cpumask_t *doms_new,
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{
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int i, j;
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lock_doms_cur();
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mutex_lock(&sched_domains_mutex);
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/* always unregister in case we don't destroy any domains */
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unregister_sched_domain_sysctl();
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@ -7871,7 +7862,7 @@ void partition_sched_domains(int ndoms_new, cpumask_t *doms_new,
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register_sched_domain_sysctl();
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unlock_doms_cur();
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mutex_unlock(&sched_domains_mutex);
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}
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#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
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@ -7880,8 +7871,10 @@ int arch_reinit_sched_domains(void)
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int err;
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get_online_cpus();
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mutex_lock(&sched_domains_mutex);
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detach_destroy_domains(&cpu_online_map);
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err = arch_init_sched_domains(&cpu_online_map);
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mutex_unlock(&sched_domains_mutex);
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put_online_cpus();
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return err;
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@ -7999,10 +7992,12 @@ void __init sched_init_smp(void)
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BUG_ON(sched_group_nodes_bycpu == NULL);
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#endif
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get_online_cpus();
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mutex_lock(&sched_domains_mutex);
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arch_init_sched_domains(&cpu_online_map);
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cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
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if (cpus_empty(non_isolated_cpus))
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cpu_set(smp_processor_id(), non_isolated_cpus);
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mutex_unlock(&sched_domains_mutex);
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put_online_cpus();
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/* XXX: Theoretical race here - CPU may be hotplugged now */
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hotcpu_notifier(update_sched_domains, 0);
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