Is perf_sigtrap synchronous?

[Eric W. Biederman]

I am looking at perf_sigtrap and I am confused by the code.


	/*
	 * We'd expect this to only occur if the irq_work is delayed and either
	 * ctx->task or current has changed in the meantime. This can be the
	 * case on architectures that do not implement arch_irq_work_raise().
	 */
	if (WARN_ON_ONCE(event->ctx->task != current))
		return;

	/*
	 * perf_pending_event() can race with the task exiting.
	 */
	if (current->flags & PF_EXITING)
		return;


It performs tests that absolutely can never fail if we are talking about
a synchronous exception.  The code force_sig family of functions only
make sense to use with and are only safe to use with synchronous
exceptions.

Are the tests in perf_sigtrap necessary or is perf_sigtrap not reporting
a synchronous event?

Eric