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Date:      Tue, 9 Dec 2014 13:18:54 +1100
From:      Jan Mikkelsen <janm@transactionware.com>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        marcel@freebsd.org, FreeBSD Stable Mailing List <freebsd-stable@freebsd.org>
Subject:   Re: 10.1 regression: process using serial port becomes unkillable when no modem control signals
Message-ID:  <AC807484-921F-4896-9B54-93E78FB3F189@transactionware.com>
In-Reply-To: <20141205095659.GF97072@kib.kiev.ua>
References:  <F8A3069F-B662-46B8-85BF-2F0A7AE994E0@transactionware.com> <20141205095659.GF97072@kib.kiev.ua>

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Hi,


> On 5 Dec 2014, at 20:57, Konstantin Belousov <kostikbel@gmail.com> =
wrote:
>=20
> On Fri, Dec 05, 2014 at 06:44:51PM +1100, Jan Mikkelsen wrote:
>> Hi,
>>=20
>> I have just found this problem on a machine upgraded to 10.1.
>>=20
>> When running mgetty on a serial port with nothing connected and then =
killing it the process becomes unkillable. This prevents ???shutdown =
-r??? from completing, which is particularly annoying.
>>=20
>> Giving the serial port a device which provides the right modem =
control signals lets the process exit immediately. The same hardware =
with 9.3 was fine.
>>=20
>> Below is the kernel stack trace on the unkillable process.
>>=20
>> Does this ring any bells for anyone?
>=20
> This sounds as something that might be fixed by r272786 and r272789
> in HEAD.  I did not looked into details too close.
>=20
> The changes are not in stable/10, apply manually and test.

These resolved the problem. Applying these changes to stable/10 seems =
like it would be a good idea.

Thanks!

Jan.


>>=20
>> Thanks,
>>=20
>> Jan Mikkelsen
>>=20
>> (kgdb) bt
>> #0  sched_switch (td=3D0xfffff80236e1a920, newtd=3D<value optimized =
out>, flags=3D<value optimized out>) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/sched_ule.=
c:1945
>> #1  0xffffffff80939ba1 in mi_switch (flags=3D260, newtd=3D0x0) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/kern_synch=
.c:494
>> #2  0xffffffff80976d6b in sleepq_catch_signals =
(wchan=3D0xfffff8000c7344b8, pri=3D0) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/subr_sleep=
queue.c:426
>> #3  0xffffffff80976c1f in sleepq_wait_sig (wchan=3D0x0, pri=3D0) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/subr_sleep=
queue.c:631
>> #4  0xffffffff808e345a in _cv_wait_sig (cvp=3D0xfffff8000c7344b8, =
lock=3D0xfffff8000c734408) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/kern_condv=
ar.c:258
>> #5  0xffffffff809957a5 in ttydev_leave (tp=3D0xfffff8000c734400) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/tty.c:1392=

>> #6  0xffffffff80994d30 in ttydev_close (dev=3D<value optimized out>, =
fflag=3D0, devtype=3D0, td=3D0x0) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/tty.c:353
>> #7  0xffffffff8081ec63 in devfs_close (ap=3D0xfffffe0c541d57e0) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/fs/devfs/devfs_=
vnops.c:592
>> #8  0xffffffff80e6d281 in VOP_CLOSE_APV (vop=3D<value optimized out>, =
a=3D<value optimized out>) at vnode_if.c:535
>> #9  0xffffffff809df673 in vn_close (vp=3D0xfffff80236a6f588, flags=3D3,=
 file_cred=3D0xfffff806a300b200, td=3D0xfffff80236e1a920) at =
vnode_if.h:225
>> #10 0xffffffff809de4c8 in vn_closefile (fp=3D0xfffff8001243d9b0, =
td=3D0xfffff80236e1a920) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/vfs_vnops.=
c:1557
>> #11 0xffffffff808204bc in devfs_close_f (fp=3D0xfffff8001243d9b0, =
td=3D0x0) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/fs/devfs/devfs_=
vnops.c:611
>> #12 0xffffffff808ed249 in _fdrop (fp=3D0xfffff8001243d9b0, td=3D0x0) =
at file.h:343
>> #13 0xffffffff808ef9ae in closef (fp=3D<value optimized out>, =
td=3D<value optimized out>) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/kern_descr=
ip.c:2335
>> #14 0xffffffff808ef5c9 in fdescfree (td=3D0xfffff80236e1a920) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/kern_descr=
ip.c:2103
>> #15 0xffffffff808fb8fb in exit1 (td=3D0xfffff80236e1a920, rv=3D<value =
optimized out>) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/kern_exit.=
c:329
>> #16 0xffffffff808fb37e in sys_sys_exit (td=3D0x0, uap=3D<value =
optimized out>) at =
/usr/home/janm/p4/freebsd-image-std-2014.2/FreeBSD/src/sys/kern/kern_exit.=
c:153
>> #17 0xffffffff80d4f521 in amd64_syscall (td=3D0xfffff80236e1a920, =
traced=3D0) at subr_syscall.c:134
>>=20
>>=20
>> _______________________________________________
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