On Thu, Aug 31, 2023 at 01:05:11PM +0300, Vitaliy Makkoveev wrote:
> On Thu, Aug 31, 2023 at 11:26:42AM +0200, Jeremie Courreges-Anglas wrote:
> >
> > Looks umb(4) triggers the NET_ASSERT_LOCKED() check in
> > rtable_getsource() when the umb(4) interface comes up (here with
> > kern.splassert=2 to get context). Reproduced with GENERIC.MP from Aug
> > 28 as well with cvs HEAD/if_umb.c rev 1.54.
> >
> > Something to worry about?
> >
> >
> > OpenBSD 7.3-current (GENERIC.MP) #1357: Mon Aug 28 20:14:09 MDT 2023
> > dera...@amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP
> > [...]
> > umb0 at uhub0 port 3 configuration 1 interface 0 "FIBOCOM L831-EAU-00" rev
> > 2.00/17.29 addr 2
> > [...]
> > splassert: rtable_getsource: want 2 have 0
> > Starting stack trace...
> > rtable_getsource(0,2) at rtable_getsource+0x58
> > rtm_send(fffffd83b1a817e0,1,0,0) at rtm_send+0xbc
> > umb_add_inet_config(ffff8000017c7000,edf0e72e,18,1f0e72e) at
> > umb_add_inet_config+0x2a8
> > umb_decode_ip_configuration(ffff8000017c7000,ffff800001ccf230,50) at
> > umb_decode_ip_configuration+0x147
> > umb_get_response_task(ffff8000017c7000) at umb_get_response_task+0xda
> > usb_task_thread(ffff800022fe0010) at usb_task_thread+0xe5
> > end trace frame: 0x0, count: 251
> > End of stack trace.
> >
>
> rtable_getsource() requires at least shared netlock to be held. It can't
> be taken within rtm_send() because we have paths where caller already
> holds it.
I am not sure if rtm_miss() a few lines above should run without
netlock. Could we just move the NET_UNLOCK() currenly above the
if block after the else block?
NET_UNLOCK() and NET_LOCK_SHARED() just after each other does not
make much sense. Just keep exclusive netlock for the few lines.
bluhm
> Index: sys/dev/usb/if_umb.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/usb/if_umb.c,v
> retrieving revision 1.54
> diff -u -p -r1.54 if_umb.c
> --- sys/dev/usb/if_umb.c 29 Aug 2023 23:28:38 -0000 1.54
> +++ sys/dev/usb/if_umb.c 31 Aug 2023 10:03:13 -0000
> @@ -1859,7 +1859,9 @@ umb_add_inet_config(struct umb_softc *sc
> ifp->if_rdomain);
> } else {
> /* Inform listeners of the new route */
> + NET_LOCK_SHARED();
> rtm_send(rt, RTM_ADD, rv, ifp->if_rdomain);
> + NET_UNLOCK_SHARED();
> rtfree(rt);
> }
>
> @@ -1940,7 +1942,9 @@ umb_add_inet6_config(struct umb_softc *s
> ifp->if_rdomain);
> } else {
> /* Inform listeners of the new route */
> + NET_LOCK_SHARED();
> rtm_send(rt, RTM_ADD, rv, ifp->if_rdomain);
> + NET_UNLOCK_SHARED();
> rtfree(rt);
> }
>
