// (Other calls to add or addNonGo should be blocked out
	// by the fact that only one SIGPROF can be handled by the
	// process at a time. If not, this lock will serialize those too.
	// The use of timer_create(2) on Linux to request process-targeted
	// signals may have changed this.)
	for !prof.signalLock.CompareAndSwap(0, 1) {
		// TODO: Is it safe to osyield here? https://go.dev/issue/52672
		osyield()
	}