Function kern_sigsuspend

freebsd/kern/kern_sig.c:1527–1579

}

int
kern_sigsuspend(struct thread *td, sigset_t mask)
{
	struct proc *p = td->td_proc;
	int has_sig, sig;

	/* Ensure the sigfastblock value is up to date. */
	sigfastblock_fetch(td);

	/*
	 * When returning from sigsuspend, we want
	 * the old mask to be restored after the
	 * signal handler has finished.  Thus, we
	 * save it here and mark the sigacts structure
	 * to indicate this.
	 */
	PROC_LOCK(p);
	kern_sigprocmask(td, SIG_SETMASK, &mask, &td->td_oldsigmask,
	    SIGPROCMASK_PROC_LOCKED);
	td->td_pflags |= TDP_OLDMASK;

	/*
	 * Process signals now. Otherwise, we can get spurious wakeup
	 * due to signal entered process queue, but delivered to other
	 * thread. But sigsuspend should return only on signal
	 * delivery.
	 */
	(p->p_sysent->sv_set_syscall_retval)(td, EINTR);
	for (has_sig = 0; !has_sig;) {
		while (msleep(&p->p_sigacts, &p->p_mtx, PPAUSE|PCATCH, "pause",
			0) == 0)
			/* void */;
		thread_suspend_check(0);
		mtx_lock(&p->p_sigacts->ps_mtx);
		while ((sig = cursig(td)) != 0) {
			KASSERT(sig >= 0, ("sig %d", sig));
			has_sig += postsig(sig);
		}
		mtx_unlock(&p->p_sigacts->ps_mtx);

		/*
		 * If PTRACE_SCE or PTRACE_SCX were set after
		 * userspace entered the syscall, return spurious
		 * EINTR.
		 */
		if ((p->p_ptevents & PTRACE_SYSCALL) != 0)
			has_sig += 1;
	}
	PROC_UNLOCK(p);
	td->td_errno = EINTR;
	td->td_pflags |= TDP_NERRNO;
	return (EJUSTRETURN);
}

#ifdef COMPAT_43	/* XXX - COMPAT_FBSD3 */
/*