On Friday 30 September 2005 11:25 am, Antoine Pelisse wrote:
> On 9/30/05, John Baldwin <[EMAIL PROTECTED]> wrote:
> > On Friday 30 September 2005 05:24 am, Antoine Pelisse wrote:
> > > Hi Robert,
> > > I don't think your patch is correct, the total linked list can be
> > > broken
> > >
> > > while the lock is released, thus just passing the link may not be
> > > enough I have submitted a PR[1] for this a month ago but nobody took
> > > care of it yet Regards,
> > > Antoine Pelisse
> > >
> > > [1] http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/84684
> >
> > I think this patch looks ok. Robert, can you get the original panic on
> > this
> > thread tested against this patch?
>
> I had a small program which could reproduce this panic in 10 seconds, it
> was basically creating empty threads and calling kvm_getprocs() in the same
> time. Anyway the patch was able to stop the program from panicing.
> The panic is also reproducible in RELENG_6 and HEAD IIRC.
It turns out that the sysctl buffer is already wired in one of the two cases
that this function is called, so I moved the wiring up to the upper layer in
the other case and cut out a bunch of the locking gymnastics as a result.
Can you try this patch?
Index: kern_proc.c
===================================================================
RCS file: /usr/cvs/src/sys/kern/kern_proc.c,v
retrieving revision 1.231
diff -u -r1.231 kern_proc.c
--- kern_proc.c 27 Sep 2005 18:03:15 -0000 1.231
+++ kern_proc.c 30 Sep 2005 17:04:57 -0000
@@ -875,22 +875,16 @@
if (flags & KERN_PROC_NOTHREADS) {
fill_kinfo_proc(p, &kinfo_proc);
- PROC_UNLOCK(p);
error = SYSCTL_OUT(req, (caddr_t)&kinfo_proc,
sizeof(kinfo_proc));
- PROC_LOCK(p);
} else {
- _PHOLD(p);
FOREACH_THREAD_IN_PROC(p, td) {
fill_kinfo_thread(td, &kinfo_proc);
- PROC_UNLOCK(p);
error = SYSCTL_OUT(req, (caddr_t)&kinfo_proc,
sizeof(kinfo_proc));
- PROC_LOCK(p);
if (error)
break;
}
- _PRELE(p);
}
PROC_UNLOCK(p);
if (error)
@@ -932,6 +926,9 @@
if (oid_number == KERN_PROC_PID) {
if (namelen != 1)
return (EINVAL);
+ error = sysctl_wire_old_buffer(req, 0);
+ if (error)
+ return (error);
p = pfind((pid_t)name[0]);
if (!p)
return (ESRCH);
--
John Baldwin <[EMAIL PROTECTED]> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve" = http://www.FreeBSD.org
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