The current __perf_install_in_context can fail and the error is ignored. Changing __perf_install_in_context can add new failure modes that need errors propagating up. This change prepares for this.
Signed-off-by: Ian Rogers <[email protected]> --- kernel/events/core.c | 38 +++++++++++++++++++++++++------------- 1 file changed, 25 insertions(+), 13 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 785d708f8553..4faa90f5a934 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2558,11 +2558,12 @@ static int __perf_install_in_context(void *info) * * Very similar to event_function_call, see comment there. */ -static void +static int perf_install_in_context(struct perf_event_context *ctx, struct perf_event *event, int cpu) { + int err; struct task_struct *task = READ_ONCE(ctx->task); lockdep_assert_held(&ctx->mutex); @@ -2577,15 +2578,15 @@ perf_install_in_context(struct perf_event_context *ctx, smp_store_release(&event->ctx, ctx); if (!task) { - cpu_function_call(cpu, __perf_install_in_context, event); - return; + err = cpu_function_call(cpu, __perf_install_in_context, event); + return err; } /* * Should not happen, we validate the ctx is still alive before calling. */ if (WARN_ON_ONCE(task == TASK_TOMBSTONE)) - return; + return 0; /* * Installing events is tricky because we cannot rely on ctx->is_active @@ -2619,8 +2620,9 @@ perf_install_in_context(struct perf_event_context *ctx, */ smp_mb(); again: - if (!task_function_call(task, __perf_install_in_context, event)) - return; + err = task_function_call(task, __perf_install_in_context, event); + if (err) + return err; raw_spin_lock_irq(&ctx->lock); task = ctx->task; @@ -2631,7 +2633,7 @@ perf_install_in_context(struct perf_event_context *ctx, * against perf_event_exit_task_context(). */ raw_spin_unlock_irq(&ctx->lock); - return; + return 0; } /* * If the task is not running, ctx->lock will avoid it becoming so, @@ -2643,6 +2645,7 @@ perf_install_in_context(struct perf_event_context *ctx, } add_event_to_ctx(event, ctx); raw_spin_unlock_irq(&ctx->lock); + return 0; } /* @@ -11103,7 +11106,9 @@ SYSCALL_DEFINE5(perf_event_open, */ for_each_sibling_event(sibling, group_leader) { perf_event__state_init(sibling); - perf_install_in_context(ctx, sibling, sibling->cpu); + err = perf_install_in_context(ctx, sibling, + sibling->cpu); + WARN_ON_ONCE(err); get_ctx(ctx); } @@ -11113,7 +11118,9 @@ SYSCALL_DEFINE5(perf_event_open, * startup state, ready to be add into new context. */ perf_event__state_init(group_leader); - perf_install_in_context(ctx, group_leader, group_leader->cpu); + err = perf_install_in_context(ctx, group_leader, + group_leader->cpu); + WARN_ON_ONCE(err); get_ctx(ctx); } @@ -11128,7 +11135,8 @@ SYSCALL_DEFINE5(perf_event_open, event->owner = current; - perf_install_in_context(ctx, event, event->cpu); + err = perf_install_in_context(ctx, event, event->cpu); + WARN_ON_ONCE(err); perf_unpin_context(ctx); if (move_group) @@ -11247,7 +11255,8 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, goto err_unlock; } - perf_install_in_context(ctx, event, cpu); + err = perf_install_in_context(ctx, event, cpu); + WARN_ON_ONCE(err); perf_unpin_context(ctx); mutex_unlock(&ctx->mutex); @@ -11270,6 +11279,7 @@ void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu) struct perf_event_context *dst_ctx; struct perf_event *event, *tmp; LIST_HEAD(events); + int err; src_ctx = &per_cpu_ptr(pmu->pmu_cpu_context, src_cpu)->ctx; dst_ctx = &per_cpu_ptr(pmu->pmu_cpu_context, dst_cpu)->ctx; @@ -11308,7 +11318,8 @@ void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu) if (event->state >= PERF_EVENT_STATE_OFF) event->state = PERF_EVENT_STATE_INACTIVE; account_event_cpu(event, dst_cpu); - perf_install_in_context(dst_ctx, event, dst_cpu); + err = perf_install_in_context(dst_ctx, event, dst_cpu); + WARN_ON_ONCE(err); get_ctx(dst_ctx); } @@ -11321,7 +11332,8 @@ void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu) if (event->state >= PERF_EVENT_STATE_OFF) event->state = PERF_EVENT_STATE_INACTIVE; account_event_cpu(event, dst_cpu); - perf_install_in_context(dst_ctx, event, dst_cpu); + err = perf_install_in_context(dst_ctx, event, dst_cpu); + WARN_ON_ONCE(err); get_ctx(dst_ctx); } mutex_unlock(&dst_ctx->mutex); -- 2.22.0.410.gd8fdbe21b5-goog
