Re: rump LOCKDEBUG panic

[Paul Goyette <paul%whooppee.com@localhost>]

On Fri, Jan 13, 2017, Patrick Welche wrote:
...
> > NetBSD 7.99.58 (RUMP-ROAST)
> > ...
> > audio0 at pad0: half duplex, playback, capture
> > mutex error: lockdebug_alloc: already initialized
> >
> > lock address : 0x00007f7ff6604300 type     :     sleep/adaptive
> > initialized  : 0x00007f7ff640294a
> > shared holds :                  0 exclusive:                  0
> > shares wanted:                  0 exclusive:                  0
> > current cpu  :                  0 last held:                  0
> > current lwp  : 0x00007f7ff7b3f800 last held: 000000000000000000
> > last locked  : 000000000000000000 unlocked*: 000000000000000000
> >
> >
> > panic: LOCKDEBUG: mutex error: lockdebug_alloc: already initialized
>
> It seems taht drvctl_init gets called twice:
>
> first call of drvctl_init
>
> #0  drvctl_init ()
>     at /usr/src/sys/rump/dev/lib/libdrvctl/../../../../kern/kern_drvctl.c:118
> #1  0x00007f7ff6401e29 in rumpcompinitRUMP_COMPONENT_DEV ()
>     at /usr/src/sys/rump/dev/lib/libdrvctl/drvctl_component.c:46
> #2  0x00007f7fe50d2fcd in rump_component_init
>     (type=RUMP_COMPONENT_DEV)
>     at /usr/src/sys/rump/librump/rumpkern/rump.c:606
> #3  0x00007f7fe5c0b348 in rumpcompinitRUMP__FACTION_DEV ()
>     at /usr/src/sys/rump/librump/rumpdev/rump_dev.c:54
> #4  0x00007f7fe50d2fcd in rump_component_init (type=RUMP__FACTION_DEV)
>     at /usr/src/sys/rump/librump/rumpkern/rump.c:606
> #5  0x00007f7fe50d297b in rump_init ()
>     at /usr/src/sys/rump/librump/rumpkern/rump.c:434
> #6  0x0000000000203cd9 in main (argc=1, argv=0x7f7fffffcb20)
>     at /usr/src/usr.bin/rump_allserver/rump_allserver.c:401
>
> second call:
>
> #0  drvctl_init ()
>     at /usr/src/sys/rump/dev/lib/libdrvctl/../../../../kern/kern_drvctl.c:118
> #1  0x00007f7ff6402ef2 in drvctl_modcmd (cmd=MODULE_CMD_INIT, arg=0x0)
>     at /usr/src/sys/rump/dev/lib/libdrvctl/../../../../kern/kern_drvctl.c:615
> #2  0x00007f7fe50af0c4 in module_do_builtin (pmod=0x7f7ff7bd1c98,
>     name=0x7f7ff640321b "drvctl", modp=0x0, props=0x0)
>     at /usr/src/sys/rump/librump/rumpkern/../../../kern/kern_module.c:830
> #3  0x00007f7fe50ae78c in module_init_class
>     (modclass=MODULE_CLASS_ANY)
>     at /usr/src/sys/rump/librump/rumpkern/../../../kern/kern_module.c:511
> #4  0x00007f7fe50d2a95 in rump_init ()
>     at /usr/src/sys/rump/librump/rumpkern/rump.c:459
> #5  0x0000000000203cd9 in main (argc=1, argv=0x7f7fffffcb20)
>     at /usr/src/usr.bin/rump_allserver/rump_allserver.c:401


Yeah, it seems that the rump initialization code is calling routine 
drvctl_init() in order to determine the c-major for the /dev/drvctl 
node.  The right thing to do here is to temporarily attach the cdevsw 
structure, retrieve the c-major, and then detach the cdevsw.  Later, 
normal module initialization code will handle the full-blown attach of 
the drvctl device module.

Interestingly, it seems that this code is broken in other ways, too!  In 
particular, even though it retrieves the c-major for /dev/drvctl, it 
never actually creates the device node!  So I have to wonder if you can 
even use drvctl within rump at this time!

Anyway, try the attached patch.  It should avoid the duplicate attempts 
at calling drvctl_init(), and it should also enable /dev/drvctl within 
the rump environment.  Let me know if it helps.

FWIW, I suspect the reason that no-one else sees this is because very 
few others are running a LOCKDEBUG version of the rump_all_server! 
Without LOCKDEBUG the failure will be silently ignored.


+------------------+--------------------------+------------------------+
| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:      |
| (Retired)        | FA29 0E3B 35AF E8AE 6651 | paul at whooppee.com   |
| Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd.org |
+------------------+--------------------------+------------------------+

Index: drvctl_component.c
===================================================================
RCS file: /cvsroot/src/sys/rump/dev/lib/libdrvctl/drvctl_component.c,v
retrieving revision 1.2
diff -u -p -r1.2 drvctl_component.c
--- drvctl_component.c	26 Jan 2016 23:12:15 -0000	1.2
+++ drvctl_component.c	14 Jan 2017 09:28:16 -0000
@@ -43,13 +43,13 @@ RUMP_COMPONENT(RUMP_COMPONENT_DEV)
 	devmajor_t bmaj, cmaj;
 	int error;
 
-	drvctl_init();
-
-	config_init_component(cfdriver_ioconf_drvctl,
-	    cfattach_ioconf_drvctl, cfdata_ioconf_drvctl);
-
 	bmaj = cmaj = NODEVMAJOR;
 	if ((error = devsw_attach("drvctl", NULL, &bmaj,
 	    &drvctl_cdevsw, &cmaj)) != 0)
 		panic("drvctl devsw attach failed: %d", error);
+        if ((error = rump_vfs_makeonedevnode(S_IFCHR, "/dev/drvctl", cmaj, 0))
+	    !=0)
+                panic("cannot create drvctl device node: %d", error);
+        if ((error = devsw_detach(NULL, &drvctl_cdevsw)) != 0)
+                panic("cannot detach drvctl devsw: %d", error);
 }