diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/stop_machine.c | 111 |
1 files changed, 41 insertions, 70 deletions
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index af3c7cea258b..0e688c6a1a63 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -37,9 +37,13 @@ struct stop_machine_data { /* Like num_online_cpus(), but hotplug cpu uses us, so we need this. */ static unsigned int num_threads; static atomic_t thread_ack; -static struct completion finished; static DEFINE_MUTEX(lock); +static struct workqueue_struct *stop_machine_wq; +static struct stop_machine_data active, idle; +static const cpumask_t *active_cpus; +static void *stop_machine_work; + static void set_state(enum stopmachine_state newstate) { /* Reset ack counter. */ @@ -51,21 +55,25 @@ static void set_state(enum stopmachine_state newstate) /* Last one to ack a state moves to the next state. */ static void ack_state(void) { - if (atomic_dec_and_test(&thread_ack)) { - /* If we're the last one to ack the EXIT, we're finished. */ - if (state == STOPMACHINE_EXIT) - complete(&finished); - else - set_state(state + 1); - } + if (atomic_dec_and_test(&thread_ack)) + set_state(state + 1); } -/* This is the actual thread which stops the CPU. It exits by itself rather - * than waiting for kthread_stop(), because it's easier for hotplug CPU. */ -static int stop_cpu(struct stop_machine_data *smdata) +/* This is the actual function which stops the CPU. It runs + * in the context of a dedicated stopmachine workqueue. */ +static void stop_cpu(struct work_struct *unused) { enum stopmachine_state curstate = STOPMACHINE_NONE; - + struct stop_machine_data *smdata = &idle; + int cpu = smp_processor_id(); + + if (!active_cpus) { + if (cpu == first_cpu(cpu_online_map)) + smdata = &active; + } else { + if (cpu_isset(cpu, *active_cpus)) + smdata = &active; + } /* Simple state machine */ do { /* Chill out and ensure we re-read stopmachine_state. */ @@ -90,7 +98,6 @@ static int stop_cpu(struct stop_machine_data *smdata) } while (curstate != STOPMACHINE_EXIT); local_irq_enable(); - do_exit(0); } /* Callback for CPUs which aren't supposed to do anything. */ @@ -101,78 +108,34 @@ static int chill(void *unused) int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus) { - int i, err; - struct stop_machine_data active, idle; - struct task_struct **threads; + struct work_struct *sm_work; + int i; + /* Set up initial state. */ + mutex_lock(&lock); + num_threads = num_online_cpus(); + active_cpus = cpus; active.fn = fn; active.data = data; active.fnret = 0; idle.fn = chill; idle.data = NULL; - /* This could be too big for stack on large machines. */ - threads = kcalloc(NR_CPUS, sizeof(threads[0]), GFP_KERNEL); - if (!threads) - return -ENOMEM; - - /* Set up initial state. */ - mutex_lock(&lock); - init_completion(&finished); - num_threads = num_online_cpus(); set_state(STOPMACHINE_PREPARE); - for_each_online_cpu(i) { - struct stop_machine_data *smdata = &idle; - struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; - - if (!cpus) { - if (i == first_cpu(cpu_online_map)) - smdata = &active; - } else { - if (cpu_isset(i, *cpus)) - smdata = &active; - } - - threads[i] = kthread_create((void *)stop_cpu, smdata, "kstop%u", - i); - if (IS_ERR(threads[i])) { - err = PTR_ERR(threads[i]); - threads[i] = NULL; - goto kill_threads; - } - - /* Place it onto correct cpu. */ - kthread_bind(threads[i], i); - - /* Make it highest prio. */ - if (sched_setscheduler_nocheck(threads[i], SCHED_FIFO, ¶m)) - BUG(); - } - - /* We've created all the threads. Wake them all: hold this CPU so one + /* Schedule the stop_cpu work on all cpus: hold this CPU so one * doesn't hit this CPU until we're ready. */ get_cpu(); - for_each_online_cpu(i) - wake_up_process(threads[i]); - + for_each_online_cpu(i) { + sm_work = percpu_ptr(stop_machine_work, i); + INIT_WORK(sm_work, stop_cpu); + queue_work_on(i, stop_machine_wq, sm_work); + } /* This will release the thread on our CPU. */ put_cpu(); - wait_for_completion(&finished); + flush_workqueue(stop_machine_wq); mutex_unlock(&lock); - - kfree(threads); - return active.fnret; - -kill_threads: - for_each_online_cpu(i) - if (threads[i]) - kthread_stop(threads[i]); - mutex_unlock(&lock); - - kfree(threads); - return err; } int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus) @@ -187,3 +150,11 @@ int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus) return ret; } EXPORT_SYMBOL_GPL(stop_machine); + +static int __init stop_machine_init(void) +{ + stop_machine_wq = create_rt_workqueue("kstop"); + stop_machine_work = alloc_percpu(struct work_struct); + return 0; +} +early_initcall(stop_machine_init); |