Date: Sat, 15 Sep 2001 18:35:54 +0200 (CEST) From: Maxime Henrion <mux@qualys.com> To: FreeBSD-gnats-submit@freebsd.org Subject: kern/30593: [PATCH] panic: static sysctl oid too high: 684 - when unloading snd_es137x.ko Message-ID: <200109151635.f8FGZsA01372@nebula.cybercable.fr>
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>Number: 30593
>Category: kern
>Synopsis: [PATCH] panic: static sysctl oid too high: 684 - when unloading snd_es137x.ko
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sat Sep 15 10:40:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator: Maxime Henrion
>Release: FreeBSD 5.0-CURRENT i386
>Organization:
<organization of PR author (multiple lines)>
>Environment:
System: FreeBSD nebula.cybercable.fr 5.0-CURRENT FreeBSD 5.0-CURRENT #103: Sat Sep 15 18:03:06 CEST 2001 mux@nebula.cybercable.fr:/usr/src/sys/i386/compile/NEBULA i386
>Description:
panic: static sysctl oid too high: 684
(kgdb) bt
[...]
#10 0xc0189716 in sysctl_register_oid (oidp=0xc19710c0)
at ../../../kern/kern_sysctl.c:127
#11 0xc01897f8 in sysctl_ctx_free (clist=0xc0cd3c68)
at ../../../kern/kern_sysctl.c:192
(kgdb) list
191 while (e1 != NULL) {
192 sysctl_register_oid(e1->entry);
193 e1 = TAILQ_PREV(e1, sysctl_ctx_list, link);
194 }
(kgdb) print *e1->entry
$1 = {oid_parent = 0xc033d040, oid_link = {sle_next = 0x0}, oid_number = 684,
oid_kind = -2113929215, oid_arg1 = 0xc0cd8540, oid_arg2 = 0,
oid_name = 0xc0cd8550 "pcm0", oid_handler = 0, oid_fmt = 0xc0338b3d "N",
oid_refcnt = 1}
(kgdb) printf "%x\n",e1->entry->oid_kind
82000001
^
CTLFLAG_DYN
From src/sys/kern/kern_sysctl.c in sysctl_ctx_free() :
/*
* First perform a "dry run" to check if it's ok to remove oids.
* XXX FIXME
* XXX This algorithm is a hack. But I don't know any
* XXX better solution for now...
*/
It appears in the comments of sysctl_ctx_free() that this function is a
hack. It seems it sometimes has to re-register an oid, and sometimes
tries to re-register dynamic sysctls. In that case it doesn't change
the oid_number of the oid, and just call sysctl_register_oid() which
panics because it is too high.
I'm not able to properly fix this function right now, because I don't
understand the reasons of this hack, however I can provide a patch
that sets the oid_number to OID_AUTO if it was greater or equal to
CTL_AUTO_START. With this patch applied, I can now happily load and
unload my sound modules several times.
>How-To-Repeat:
# kldunload snd_es137x
>Fix:
Note: It would perhaps be better to test oid_kind against CTLFLAG_DYN
instead of looking at the oid_number.
--- patch begins here ---
--- /usr/src/sys/kern/kern_sysctl.c Fri Sep 14 21:01:08 2001
+++ kern_sysctl.c Sat Sep 15 18:00:30 2001
@@ -189,6 +189,8 @@
else
e1 = TAILQ_LAST(clist, sysctl_ctx_list);
while (e1 != NULL) {
+ if (e1->entry->oid_number >= CTL_AUTO_START)
+ e1->entry->oid_number = OID_AUTO;
sysctl_register_oid(e1->entry);
e1 = TAILQ_PREV(e1, sysctl_ctx_list, link);
}
--- patch ends here ---
>Release-Note:
>Audit-Trail:
>Unformatted:
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