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-rw-r--r--kernel/events/core.c106
1 files changed, 76 insertions, 30 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index bc63f8db1b0d..4d2c32f98482 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:
@@ -3807,14 +3808,6 @@ 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);
@@ -7723,7 +7716,8 @@ 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);
@@ -7744,7 +7738,7 @@ 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) {
@@ -7752,8 +7746,7 @@ static int swevent_hlist_get(void)
goto fail;
}
}
- put_online_cpus();
-
+ mutex_unlock(&pmus_lock);
return 0;
fail:
for_each_possible_cpu(cpu) {
@@ -7761,8 +7754,7 @@ fail:
break;
swevent_hlist_put_cpu(cpu);
}
-
- put_online_cpus();
+ mutex_unlock(&pmus_lock);
return err;
}
@@ -8940,7 +8932,7 @@ 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);
@@ -8949,7 +8941,7 @@ 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;
@@ -9079,6 +9071,7 @@ 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);
}
@@ -9903,12 +9896,10 @@ 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_task;
/*
* Reuse ptrace permission checks for now.
@@ -10094,6 +10085,23 @@ 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.
@@ -10183,8 +10191,6 @@ SYSCALL_DEFINE5(perf_event_open,
put_task_struct(task);
}
- put_online_cpus();
-
mutex_lock(&current->perf_event_mutex);
list_add_tail(&event->owner_entry, &current->perf_event_list);
mutex_unlock(&current->perf_event_mutex);
@@ -10218,8 +10224,6 @@ 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);
@@ -10274,6 +10278,21 @@ 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;
@@ -10941,6 +10960,8 @@ 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);
@@ -10956,7 +10977,7 @@ 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);
@@ -10969,7 +10990,6 @@ 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
@@ -10987,19 +11007,22 @@ 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
@@ -11007,6 +11030,29 @@ 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);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 09:12:28 +0000