On 30 Sep, John Baldwin wrote: > 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); >
sched_lock needs to be grabbed before the FOREACH_THREAD_IN_PROC loop. Can _PHOLD()/_PRELE() be dropped? _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
