Date: Fri, 18 Oct 2013 18:17:47 -0600 From: "Justin T. Gibbs" <gibbs@FreeBSD.org> To: "Steven Hartland" <killing@multiplay.co.uk> Cc: hackers@freebsd.org Subject: Re: panic on close of /dev/xen/evtchn Message-ID: <96E387D7-C92C-4945-AD7B-F9C917BCCDC6@FreeBSD.org> In-Reply-To: <67CB0311850E47498A3E288F7A6CB9B5@multiplay.co.uk> References: <D8F3EEBB468441BC94618864FB2E0B04@multiplay.co.uk> <67CB0311850E47498A3E288F7A6CB9B5@multiplay.co.uk>
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With the roto-tilling of the event channel stuff, I'm not sure that the =
evtchn device works
properly in a Xen environment. We should probably just disable it =
globally for now.
I will look into it more later tonight and tomorrow.
--
Justin
On Oct 18, 2013, at 6:04 PM, "Steven Hartland" <killing@multiplay.co.uk> =
wrote:
> Having a quick look I believe this device shouldn't even
> be initialised unless its running under xen so I believe
> the correct fix is:-
>=20
> svn diff sys/xen/evtchn/evtchn_dev.c
> Index: sys/xen/evtchn/evtchn_dev.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- sys/xen/evtchn/evtchn_dev.c (revision 256554)
> +++ sys/xen/evtchn/evtchn_dev.c (working copy)
> @@ -325,23 +325,23 @@
> .d_name =3D "evtchn",
> };
>=20
> -
> /* XXX - if this device is ever supposed to support use by more than =
one process
> * this global static will have to go away
> */
> static struct cdev *evtchn_dev;
>=20
> -
> -
> -static int
> +static void
> evtchn_dev_init(void *dummy __unused)
> {
> + if (!is_running_on_xen())
> + return;
> +
> /* XXX I believe we don't need these leaving them here for now =
until we
> * have some semblance of it working
> */
> mtx_init(&upcall_lock, "evtchup", NULL, MTX_DEF);
>=20
> - /* (DEVFS) create '/dev/misc/evtchn'. */
> + /* (DEVFS) create '/dev/xen/evtchn'. */
> evtchn_dev =3D make_dev(&evtchn_devsw, 0, UID_ROOT, GID_WHEEL, =
0600, "xen/evtchn");
>=20
> mtx_init(&lock, "evch", NULL, MTX_SPIN | MTX_NOWITNESS);
> @@ -351,8 +351,6 @@
>=20
> if (bootverbose)
> printf("Event-channel device installed.\n");
> -
> - return 0;
> }
>=20
> SYSINIT(evtchn_dev_init, SI_SUB_DRIVERS, SI_ORDER_FIRST, =
evtchn_dev_init, NULL);
>=20
> Yes / No?
>=20
> Regards
> Steve
> ----- Original Message ----- From: "Steven Hartland" =
<killing@multiplay.co.uk>
> To: <hackers@freebsd.org>
> Sent: Friday, October 18, 2013 4:33 PM
> Subject: panic on close of /dev/xen/evtchn
>=20
>=20
>> Just had my test box panic while doing a:
>> find / -print0 | xargs -0 cat
>>=20
>> Ignoring the fact thats a silly command to run, the
>> panic appears to be when it ran:
>> cat /dev/xen/evtchn
>>=20
>> On the session it then printed:
>> cat: /dev/xen/evtchn: Interrupted system call
>>=20
>> At this point the system paniced.
>>=20
>> Panic transcribed from screen is:
>>=20
>> Stopped at evtchn_close:0x67: lock bts| %ebx,0xa00(%rax)
>>=20
>> db> bt
>> Tracing pdi 1533 tid 100370 td 0xfffff8000796e920
>> evtchn_close() at evtchn_close+0x67/frame ...
>> devfs_close() at devs_close+0x188/frame ...
>> VOP_CLOSE_APV() at VOP_CLOSE_APV+0x139/frame ...
>> vn_close() at vn_close+0x139/frame ...
>> vn_closefile() at vn_closefile+0x48/frame ...
>> _fdrop() at _fdrop+0x29/frame ...
>> closef() at closef+0x1d1/frame ...
>> closefp() at closefp+0xa0/frame ...
>> amd64_syscall() at amd64_syscall+0x265/frame ...
>> Xfast_syscall() at Xfast_syscall+0xfb/frame ...
>> --- syscall (6, FreeBSD ELF64, sys_close), rip =3D 0x80094a9ea, rsp =3D=
0x7ffffffb8e28, rbp -=3D 0x7ffffffb8f70 ---
>>=20
>> Regards
>> Steve
>>=20
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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>=20
>=20
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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>=20
>=20
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