Date: Thu, 5 Nov 1998 01:13:34 -0500 (EST) From: Brian Feldman <green@unixhelp.org> To: Peter Wemm <peter@netplex.com.au> Cc: current@FreeBSD.ORG Subject: Re: RFSIGSHARE: forgot patch ;) Message-ID: <Pine.BSF.4.05.9811050110520.28066-100000@janus.syracuse.net> In-Reply-To: <199811050357.LAA03894@spinner.netplex.com.au>
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Hrmm.... I don't see why this doesn't work:
+ if (args->flags & CLONE_SIGHAND)
+ p2->p_sigacts = p->p_sigacts;
don't tell me it's pointing into user-space, or some other neglected part
of proc? I'll investigate I suppose. This is certainly helping me
familiarize myself with the kernel, even if these specific patches cause a
trap eventually (probably all the mallocing/freeing). I _really_ need to
buy a copy of the BSD book... quick question: zalloc and malloc should
each be used in what situations?
Cheers,
Brian Feldman
"gaining lots of experience"
On Thu, 5 Nov 1998, Peter Wemm wrote:
> Brian Feldman wrote:
> [..]
> > --- ./kern/kern_fork.c.orig Wed Nov 4 20:33:11 1998
> > +++ ./kern/kern_fork.c Wed Nov 4 20:44:29 1998
> > @@ -151,6 +151,10 @@
> > p1->p_pid);
> > return (EOPNOTSUPP);
> > }
> > + if (flags & RFSIGSHARE) {
> > + printf("shared signal space attemped: pid: %d\n",
> > p1->p_pid);
> > + return (EOPNOTSUPP);
> > + }
> > #endif
> >
> > /*
>
> RFSIGSHARE should work fine on SMP.
>
> > @@ -320,6 +324,16 @@
> > bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred));
> > p2->p_cred->p_refcnt = 1;
> > crhold(p1->p_ucred);
> > +
> > + if (flags & RFSIGSHARE) {
> > + p2->p_sig->p_refcnt++;
> > + } else {
> > + p2->p_sig = malloc(sizeof(struct procsig), M_TEMP,
> > M_WAITOK);
> > + p2->p_sig->p_refcnt = 1;
> > + p2->p_sigmask = p1->p_sigmask;
> > + p2->p_sigignore = p1->p_sigignore;
> > + p2->p_sigcatch = p1->p_sigcatch;
> > + }
> >
> > /* bump references to the text vnode (for procfs) */
> > p2->p_textvp = p1->p_textvp;
>
> Umm, you are sharing the signal masks, not the signal handler vectors
> themselves. Think p_sigacts.. Those are stored after the PCB and are
> paged out.
>
> Assuming you take a shot at sharing them, try this: Keep p_sigacts there
> by default. If a process attempts to share the signals during a fork,
> then malloc a copy and attach it to both the child and parent. When the
> reference count drops to 1, the remaining process should probably have
> it's vectors copied to the upages again and the malloc space freed. But
> good stuff so far! :-)
>
> Cheers,
> -Peter
>
>
>
>
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