> Date: Thu, 11 Nov 2021 13:30:04 -0600
> From: Scott Cheloha <[email protected]>
>
> My understanding of sigsuspend(2) is that it only returns if a signal
> is delivered to the calling thread. However, in sys_sigsuspend() we
> pass &p->p_p->ps_sigacts as the wakeup channel to tsleep_nsec(9).
>
> Are we actually waiting for a wakeup on that channel? Or can we sleep
> on &nowake here? Patch attached. Note that we don't need to loop
> here anymore: we can't receieve wakeup so tsleep_nsec(9) will never
> return zero.
I don't think we expect a wakeup on that channel. But the loop is
still needed as a spurious wakeup may happen.
> I can't find any wakeups in the kernel sent to any ps_sigacts, but
> maybe I missed something.
>
> If not, ok?
>
> Index: kern_sig.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_sig.c,v
> retrieving revision 1.287
> diff -u -p -r1.287 kern_sig.c
> --- kern_sig.c 24 Oct 2021 00:02:25 -0000 1.287
> +++ kern_sig.c 11 Nov 2021 19:24:49 -0000
> @@ -509,7 +509,7 @@ dosigsuspend(struct proc *p, sigset_t ne
> }
>
> /*
> - * Suspend process until signal, providing mask to be set
> + * Suspend thread until signal, providing mask to be set
> * in the meantime. Note nonstandard calling convention:
> * libc stub passes mask, not pointer, to save a copyin.
> */
> @@ -519,12 +519,9 @@ sys_sigsuspend(struct proc *p, void *v,
> struct sys_sigsuspend_args /* {
> syscallarg(int) mask;
> } */ *uap = v;
> - struct process *pr = p->p_p;
> - struct sigacts *ps = pr->ps_sigacts;
>
> dosigsuspend(p, SCARG(uap, mask) &~ sigcantmask);
> - while (tsleep_nsec(ps, PPAUSE|PCATCH, "sigsusp", INFSLP) == 0)
> - /* void */;
> + tsleep_nsec(&nowake, PPAUSE|PCATCH, "sigsusp", INFSLP);
> /* always return EINTR rather than ERESTART... */
> return (EINTR);
> }
>
>
