From: Vitaliy Makkoveev <mvs@openbsd.org>
Subject: Re: Unlock getpgrp(2)
To: Theo de Raadt <deraadt@openbsd.org>
Cc: tech@openbsd.org
Date: Tue, 9 Jun 2026 04:49:56 +0300

On Mon, Jun 08, 2026 at 09:57:07AM -0600, Theo de Raadt wrote:
> I don't see a problem with this.
> 

This is not the problem fix, just unlocking.

> Vitaliy Makkoveev <mvs@openbsd.org> wrote:
> 
> > `ps_pgrp' is protected by both kernel lock and `ps_mtx' mutex, so only
> > one is enough for read only access. `pg_id' has the type of pid_t.
> > 
> > The corresponding enternewpgrp() sets `ps_pgrp' to the initialized new
> > one with both locks held.
> > 
> > Index: sys/kern/kern_prot.c
> > ===================================================================
> > RCS file: /cvs/src/sys/kern/kern_prot.c,v
> > diff -u -p -r1.84 kern_prot.c
> > --- sys/kern/kern_prot.c	3 Dec 2025 17:05:53 -0000	1.84
> > +++ sys/kern/kern_prot.c	8 Jun 2026 13:13:21 -0000
> > @@ -94,7 +94,9 @@ int
> >  sys_getpgrp(struct proc *p, void *v, register_t *retval)
> >  {
> >  
> > +	mtx_enter(&p->p_p->ps_mtx);
> >  	*retval = p->p_p->ps_pgrp->pg_id;
> > +	mtx_leave(&p->p_p->ps_mtx);
> >  	return (0);
> >  }
> >  
> > Index: sys/kern/syscalls.master
> > ===================================================================
> > RCS file: /cvs/src/sys/kern/syscalls.master,v
> > diff -u -p -r1.272 syscalls.master
> > --- sys/kern/syscalls.master	2 Jun 2026 21:46:21 -0000	1.272
> > +++ sys/kern/syscalls.master	8 Jun 2026 13:13:21 -0000
> > @@ -183,7 +183,7 @@
> >  			    gid_t *gidset); }
> >  80	STD		{ int sys_setgroups(int gidsetsize, \
> >  			    const gid_t *gidset); }
> > -81	STD		{ int sys_getpgrp(void); }
> > +81	STD NOLOCK	{ int sys_getpgrp(void); }
> >  82	STD		{ int sys_setpgid(pid_t pid, pid_t pgid); }
> >  83	STD NOLOCK	{ int sys_futex(uint32_t *f, int op, int val, \
> >  			    const struct timespec *timeout, uint32_t *g); }
> >