Re: [bug report] irq_work: Allow irq_work_sync() to sleep if irq_work() no IRQ support.

[Dan Carpenter <dan.carpenter@oracle.com>]

On Wed, Jan 26, 2022 at 01:11:13PM +0100, Sebastian Andrzej Siewior wrote:
> 
> > __perf_event_exit_context() <- disables preempt
> don't see additional one.
> 
> > -> __perf_remove_from_context()

In linux-next perf_remove_from_context() calls raw_spin_lock() which
disabled preemption.

kernel/events/core.c
 13343        static void __perf_event_exit_context(void *__info)
 13344        {
 13345                struct perf_event_context *ctx = __info;
 13346                struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
 13347                struct perf_event *event;
 13348
 13349                raw_spin_lock(&ctx->lock);
                      ^^^^^^^^^^^^^^^^^^^^^^^^^
 13350                ctx_sched_out(ctx, cpuctx, EVENT_TIME);
 13351                list_for_each_entry(event, &ctx->event_list, event_entry)
 13352                        __perf_remove_from_context(event, cpuctx, ctx, (void *)DETACH_GROUP);
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 13353                raw_spin_unlock(&ctx->lock);
 13354        }

regards,
dan carpenter