On Thu, Nov 13, 2025 at 11:05:46AM -0800, Mark McBride wrote:
> I can trigger a kernel panic if I start the syncthing service.
>
> rcctl start syncthing_markmcb
>
> ... wait 5-10 seconds ...
>
> panic: netlock rwlock 0xffffff80012492d0: exit write when lock not held
> (owner 0
> x10, self 0xffffff809ee7ad24)
> Stopped at db_enter+0x18: brk #0xf000
> TID PID UID PRFLAGS PFLAGS CPU COMMAND
> 87509 73883 1000 0x3 0 2 syncthing
> 468519 73883 1000 0x3 0x4000000 3 syncthing
> * 29160 73883 1000 0x3 0x4000000 1 syncthing
> 3 22537 73883 1000 0x3 0x4000000 0 syncthing
> db_enter() at panic+0x138
> panic() at rw_exit_write+0xd0
> _rw_init_flags() at cad_ioctl+0x80
> cad_ioctl() at in_delmulti+0xbc
> in_delmulti() at ip_freemoptions+0x3c
> ip_freemoptions() at in_pcbdetach+0x5c
> in_pcbdetach() at udp_detach+0x2c
>
We don't hold netlock wile performing SIOC{G,S}IFMEDIA ifioctl()
commands, so add them to exception list too.
I can't test this diff.
Index: sys/dev/fdt/if_cad.c
===================================================================
RCS file: /cvs/src/sys/dev/fdt/if_cad.c,v
retrieving revision 1.16
diff -u -p -r1.16 if_cad.c
--- sys/dev/fdt/if_cad.c 17 Sep 2025 09:17:12 -0000 1.16
+++ sys/dev/fdt/if_cad.c 13 Nov 2025 20:05:02 -0000
@@ -596,6 +596,8 @@ cad_ioctl(struct ifnet *ifp, u_long cmd,
case SIOCGIFMEDIA:
case SIOCSIFMEDIA:
case SIOCGIFSFFPAGE:
+ case SIOCGIFMEDIA:
+ case SIOCSIFMEDIA:
netlock_held = 0;
break;
}
