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cpu-hotplug: replace per-subsystem mutexes with get_online_cpus()

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This patch converts the known per-subsystem mutexes to get_online_cpus
put_online_cpus. It also eliminates the CPU_LOCK_ACQUIRE and
CPU_LOCK_RELEASE hotplug notification events.

Signed-off-by: Gautham  R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Gautham R Shenoy
2008-01-25 21:08:02 +01:00
committed by Ingo Molnar
parent 86ef5c9a8e
commit 95402b3829
5 changed files with 36 additions and 50 deletions
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25
kernel/sched.c
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@ -439,7 +439,6 @@ struct rq {
};
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
static DEFINE_MUTEX(sched_hotcpu_mutex);
static inline void check_preempt_curr(struct rq *rq, struct task_struct *p)
{
@ -4546,13 +4545,13 @@ long sched_setaffinity(pid_t pid, cpumask_t new_mask)
struct task_struct *p;
int retval;
mutex_lock(&sched_hotcpu_mutex);
get_online_cpus();
read_lock(&tasklist_lock);
p = find_process_by_pid(pid);
if (!p) {
read_unlock(&tasklist_lock);
mutex_unlock(&sched_hotcpu_mutex);
put_online_cpus();
return -ESRCH;
}
@ -4592,7 +4591,7 @@ long sched_setaffinity(pid_t pid, cpumask_t new_mask)
}
out_unlock:
put_task_struct(p);
mutex_unlock(&sched_hotcpu_mutex);
put_online_cpus();
return retval;
}
@ -4649,7 +4648,7 @@ long sched_getaffinity(pid_t pid, cpumask_t *mask)
struct task_struct *p;
int retval;
mutex_lock(&sched_hotcpu_mutex);
get_online_cpus();
read_lock(&tasklist_lock);
retval = -ESRCH;
@ -4665,7 +4664,7 @@ long sched_getaffinity(pid_t pid, cpumask_t *mask)
out_unlock:
read_unlock(&tasklist_lock);
mutex_unlock(&sched_hotcpu_mutex);
put_online_cpus();
return retval;
}
@ -5625,9 +5624,6 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
struct rq *rq;
switch (action) {
case CPU_LOCK_ACQUIRE:
mutex_lock(&sched_hotcpu_mutex);
break;
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
@ -5697,9 +5693,6 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
spin_unlock_irq(&rq->lock);
break;
#endif
case CPU_LOCK_RELEASE:
mutex_unlock(&sched_hotcpu_mutex);
break;
}
return NOTIFY_OK;
}
@ -6655,10 +6648,10 @@ static int arch_reinit_sched_domains(void)
{
int err;
mutex_lock(&sched_hotcpu_mutex);
get_online_cpus();
detach_destroy_domains(&cpu_online_map);
err = arch_init_sched_domains(&cpu_online_map);
mutex_unlock(&sched_hotcpu_mutex);
put_online_cpus();
return err;
}
@ -6769,12 +6762,12 @@ void __init sched_init_smp(void)
{
cpumask_t non_isolated_cpus;
mutex_lock(&sched_hotcpu_mutex);
get_online_cpus();
arch_init_sched_domains(&cpu_online_map);
cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
if (cpus_empty(non_isolated_cpus))
cpu_set(smp_processor_id(), non_isolated_cpus);
mutex_unlock(&sched_hotcpu_mutex);
put_online_cpus();
/* XXX: Theoretical race here - CPU may be hotplugged now */
hotcpu_notifier(update_sched_domains, 0);