diff options
| -rw-r--r-- | include/linux/perf_event.h | 2 | ||||
| -rw-r--r-- | kernel/events/core.c | 106 |
2 files changed, 78 insertions, 30 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 24a635887f28..7d6aa29094b2 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -801,6 +801,8 @@ struct perf_cpu_context { struct list_head sched_cb_entry; int sched_cb_usage; + + int online; }; struct perf_output_handle { diff --git a/kernel/events/core.c b/kernel/events/core.c index 6e75a5c9412d..b97cda4d1777 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -389,6 +389,7 @@ static atomic_t nr_switch_events __read_mostly; static LIST_HEAD(pmus); static DEFINE_MUTEX(pmus_lock); static struct srcu_struct pmus_srcu; +static cpumask_var_t perf_online_mask; /* * perf event paranoia level: @@ -3812,14 +3813,6 @@ find_get_context(struct pmu *pmu, struct task_struct *task, if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN)) return ERR_PTR(-EACCES); - /* - * We could be clever and allow to attach a event to an - * offline CPU and activate it when the CPU comes up, but - * that's for later. - */ - if (!cpu_online(cpu)) - return ERR_PTR(-ENODEV); - cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu); ctx = &cpuctx->ctx; get_ctx(ctx); @@ -7703,7 +7696,8 @@ static int swevent_hlist_get_cpu(int cpu) int err = 0; mutex_lock(&swhash->hlist_mutex); - if (!swevent_hlist_deref(swhash) && cpu_online(cpu)) { + if (!swevent_hlist_deref(swhash) && + cpumask_test_cpu(cpu, perf_online_mask)) { struct swevent_hlist *hlist; hlist = kzalloc(sizeof(*hlist), GFP_KERNEL); @@ -7724,7 +7718,7 @@ static int swevent_hlist_get(void) { int err, cpu, failed_cpu; - get_online_cpus(); + mutex_lock(&pmus_lock); for_each_possible_cpu(cpu) { err = swevent_hlist_get_cpu(cpu); if (err) { @@ -7732,8 +7726,7 @@ static int swevent_hlist_get(void) goto fail; } } - put_online_cpus(); - + mutex_unlock(&pmus_lock); return 0; fail: for_each_possible_cpu(cpu) { @@ -7741,8 +7734,7 @@ fail: break; swevent_hlist_put_cpu(cpu); } - - put_online_cpus(); + mutex_unlock(&pmus_lock); return err; } @@ -8920,7 +8912,7 @@ perf_event_mux_interval_ms_store(struct device *dev, pmu->hrtimer_interval_ms = timer; /* update all cpuctx for this PMU */ - get_online_cpus(); + cpus_read_lock(); for_each_online_cpu(cpu) { struct perf_cpu_context *cpuctx; cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu); @@ -8929,7 +8921,7 @@ perf_event_mux_interval_ms_store(struct device *dev, cpu_function_call(cpu, (remote_function_f)perf_mux_hrtimer_restart, cpuctx); } - put_online_cpus(); + cpus_read_unlock(); mutex_unlock(&mux_interval_mutex); return count; @@ -9059,6 +9051,7 @@ skip_type: lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex); lockdep_set_class(&cpuctx->ctx.lock, &cpuctx_lock); cpuctx->ctx.pmu = pmu; + cpuctx->online = cpumask_test_cpu(cpu, perf_online_mask); __perf_mux_hrtimer_init(cpuctx, cpu); } @@ -9882,12 +9875,10 @@ SYSCALL_DEFINE5(perf_event_open, goto err_task; } - get_online_cpus(); - if (task) { err = mutex_lock_interruptible(&task->signal->cred_guard_mutex); if (err) - goto err_cpus; + goto err_cred; /* * Reuse ptrace permission checks for now. @@ -10073,6 +10064,23 @@ SYSCALL_DEFINE5(perf_event_open, goto err_locked; } + if (!task) { + /* + * Check if the @cpu we're creating an event for is online. + * + * We use the perf_cpu_context::ctx::mutex to serialize against + * the hotplug notifiers. See perf_event_{init,exit}_cpu(). + */ + struct perf_cpu_context *cpuctx = + container_of(ctx, struct perf_cpu_context, ctx); + + if (!cpuctx->online) { + err = -ENODEV; + goto err_locked; + } + } + + /* * Must be under the same ctx::mutex as perf_install_in_context(), * because we need to serialize with concurrent event creation. @@ -10162,8 +10170,6 @@ SYSCALL_DEFINE5(perf_event_open, put_task_struct(task); } - put_online_cpus(); - mutex_lock(¤t->perf_event_mutex); list_add_tail(&event->owner_entry, ¤t->perf_event_list); mutex_unlock(¤t->perf_event_mutex); @@ -10197,8 +10203,6 @@ err_alloc: err_cred: if (task) mutex_unlock(&task->signal->cred_guard_mutex); -err_cpus: - put_online_cpus(); err_task: if (task) put_task_struct(task); @@ -10253,6 +10257,21 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, goto err_unlock; } + if (!task) { + /* + * Check if the @cpu we're creating an event for is online. + * + * We use the perf_cpu_context::ctx::mutex to serialize against + * the hotplug notifiers. See perf_event_{init,exit}_cpu(). + */ + struct perf_cpu_context *cpuctx = + container_of(ctx, struct perf_cpu_context, ctx); + if (!cpuctx->online) { + err = -ENODEV; + goto err_unlock; + } + } + if (!exclusive_event_installable(event, ctx)) { err = -EBUSY; goto err_unlock; @@ -10920,6 +10939,8 @@ static void __init perf_event_init_all_cpus(void) struct swevent_htable *swhash; int cpu; + zalloc_cpumask_var(&perf_online_mask, GFP_KERNEL); + for_each_possible_cpu(cpu) { swhash = &per_cpu(swevent_htable, cpu); mutex_init(&swhash->hlist_mutex); @@ -10935,7 +10956,7 @@ static void __init perf_event_init_all_cpus(void) } } -int perf_event_init_cpu(unsigned int cpu) +void perf_swevent_init_cpu(unsigned int cpu) { struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu); @@ -10948,7 +10969,6 @@ int perf_event_init_cpu(unsigned int cpu) rcu_assign_pointer(swhash->swevent_hlist, hlist); } mutex_unlock(&swhash->hlist_mutex); - return 0; } #if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC_CORE @@ -10966,19 +10986,22 @@ static void __perf_event_exit_context(void *__info) static void perf_event_exit_cpu_context(int cpu) { + struct perf_cpu_context *cpuctx; struct perf_event_context *ctx; struct pmu *pmu; - int idx; - idx = srcu_read_lock(&pmus_srcu); - list_for_each_entry_rcu(pmu, &pmus, entry) { - ctx = &per_cpu_ptr(pmu->pmu_cpu_context, cpu)->ctx; + mutex_lock(&pmus_lock); + list_for_each_entry(pmu, &pmus, entry) { + cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu); + ctx = &cpuctx->ctx; mutex_lock(&ctx->mutex); smp_call_function_single(cpu, __perf_event_exit_context, ctx, 1); + cpuctx->online = 0; mutex_unlock(&ctx->mutex); } - srcu_read_unlock(&pmus_srcu, idx); + cpumask_clear_cpu(cpu, perf_online_mask); + mutex_unlock(&pmus_lock); } #else @@ -10986,6 +11009,29 @@ static void perf_event_exit_cpu_context(int cpu) { } #endif +int perf_event_init_cpu(unsigned int cpu) +{ + struct perf_cpu_context *cpuctx; + struct perf_event_context *ctx; + struct pmu *pmu; + + perf_swevent_init_cpu(cpu); + + mutex_lock(&pmus_lock); + cpumask_set_cpu(cpu, perf_online_mask); + list_for_each_entry(pmu, &pmus, entry) { + cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu); + ctx = &cpuctx->ctx; + + mutex_lock(&ctx->mutex); + cpuctx->online = 1; + mutex_unlock(&ctx->mutex); + } + mutex_unlock(&pmus_lock); + + return 0; +} + int perf_event_exit_cpu(unsigned int cpu) { perf_event_exit_cpu_context(cpu); |