From 95402b3829010fe1e208f44e4a158ccade88969a Mon Sep 17 00:00:00 2001 From: Gautham R Shenoy Date: Fri, 25 Jan 2008 21:08:02 +0100 Subject: cpu-hotplug: replace per-subsystem mutexes with get_online_cpus() 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 Signed-off-by: Ingo Molnar --- kernel/sched.c | 25 +++++++++---------------- 1 file changed, 9 insertions(+), 16 deletions(-) (limited to 'kernel/sched.c') diff --git a/kernel/sched.c b/kernel/sched.c index 672aa68..c0e2db6 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -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); -- cgit v1.1