NetBSD Problem Report #54387

From www@netbsd.org  Sat Jul 20 13:10:40 2019
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Date: Sat, 20 Jul 2019 13:10:38 +0000 (UTC)
From: venture37@geeklan.co.uk
Reply-To: venture37@geeklan.co.uk
To: gnats-bugs@NetBSD.org
Subject: DTrace Kernel module does not autoload on first use with GENERIC kernel
X-Send-Pr-Version: www-1.0

>Number:         54387
>Category:       kern
>Synopsis:       DTrace Kernel module does not autoload on first use with GENERIC kernel
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Jul 20 13:15:00 +0000 2019
>Closed-Date:    Mon Aug 05 19:05:45 +0000 2019
>Last-Modified:  Mon Aug 05 19:05:45 +0000 2019
>Originator:     Sevan Janiyan
>Release:        HEAD
>Organization:
>Environment:
NetBSD 8.99.51 (GENERIC) #0: Fri Jul 19 12:14:15 UTC 2019  mkrepro@mkrepro.NetBSD.org:/usr/src/sys/arch/i386/compile/GENERIC i386
>Description:
Attempting to run DTrace results in "WARNING: module error: incompatible module class for `dtrace' (3 != 1)"
Tested on NetBSD/i386 & amd64

One has to modload solaris & modload dtrace
From there, dtrace is able to load subsequent dtrace_* modules 

$ modstat |grep dtrace                                                     
dtrace              misc     filesys  -        2       - solaris
dtrace_sdt          misc     filesys  a        0       - dtrace
dtrace_syscall      misc     filesys  a        0       - dtrace
>How-To-Repeat:
Try running 'dtruss ls' or "dtrace -n 'BEGIN'"
Dtrace will not work until you have modload solaris; modload dtrace manually.
>Fix:
I suspect the change of the default value of WARNS for modules may be related but I'm not sure if the value should be reduced or this has highlighted a bug a in the module code.
Commit which changed the default WARNS value:
http://mail-index.netbsd.org/source-changes/2019/02/17/msg103560.html

>Release-Note:

>Audit-Trail:
From: "J. Hannken-Illjes" <hannken@eis.cs.tu-bs.de>
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: kern/54387: DTrace Kernel module does not autoload on first use
 with GENERIC kernel
Date: Sat, 20 Jul 2019 16:20:22 +0200

 On Sat, Jul 20, 2019 at 01:15:00PM +0000, venture37@geeklan.co.uk wrote:
 ,snip>
 > I suspect the change of the default value of WARNS for modules may be related but I'm not sure if the value should be reduced or this has highlighted a bug a in the module code.

 It was the change to external/cddl/osnet/dist/uts/common/dtrace/dtrace.c,
 Rev 1.39: Change module type to "MODULE_CLASS_MISC" to allow preloading.

 It should be sufficient to try to load module "dtrace" before we open
 the device, please try the diff attached.

 --
 J. Hannken-Illjes - hannken@eis.cs.tu-bs.de - TU Braunschweig

 diff -r 34ade923a39d external/cddl/osnet/dist/lib/libdtrace/common/dt_open.c
 --- external/cddl/osnet/dist/lib/libdtrace/common/dt_open.c	Sat Jul 20 15:54:37 2019 +0200
 +++ external/cddl/osnet/dist/lib/libdtrace/common/dt_open.c	Sat Jul 20 16:11:40 2019 +0200
 @@ -1140,6 +1140,16 @@ dt_vopen(int version, int flags, int *er
  	 */
  	dt_provmod_open(&provmod, &df);

 +#ifdef __NetBSD__
 +	modctl_load_t cmdargs;
 +
 +	cmdargs.ml_filename = "dtrace";
 +	cmdargs.ml_flags = MODCTL_NO_PROP;
 +	cmdargs.ml_props = NULL;
 +	cmdargs.ml_propslen = 0;
 +
 +	(void)modctl(MODCTL_LOAD, &cmdargs);
 +#endif
  	dtfd = open("/dev/dtrace/dtrace", O_RDWR);
  	err = errno; /* save errno from opening dtfd */
  #if defined(__FreeBSD__)

From: Sevan Janiyan <venture37@geeklan.co.uk>
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: kern/54387: DTrace Kernel module does not autoload on first use
 with GENERIC kernel
Date: Sat, 20 Jul 2019 16:20:10 +0100

 On 20/07/2019 15:25, J. Hannken-Illjes wrote:
 > please try the diff attached.

 Applied the diff & rebuilt libdtrace. dtrace module autoloads as
 expected now.

 Thank you.

 Sevan

From: "Juergen Hannken-Illjes" <hannken@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/54387 CVS commit: src/external/cddl/osnet/dist/lib/libdtrace/common
Date: Sun, 21 Jul 2019 15:37:27 +0000

 Module Name:	src
 Committed By:	hannken
 Date:		Sun Jul 21 15:37:27 UTC 2019

 Modified Files:
 	src/external/cddl/osnet/dist/lib/libdtrace/common: dt_open.c

 Log Message:
 Try to load module "dtrace" before opening "/dev/dtrace/dtrace".

 Fixes PR kern/54387: DTrace Kernel module does not autoload on first use ...


 To generate a diff of this commit:
 cvs rdiff -u -r1.13 -r1.14 \
     src/external/cddl/osnet/dist/lib/libdtrace/common/dt_open.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: open->closed
State-Changed-By: maya@NetBSD.org
State-Changed-When: Mon, 05 Aug 2019 19:05:45 +0000
State-Changed-Why:
Confirmed fixed. Thanks for the report, and thanks hannken for fixing all of the bugs :)


>Unformatted:

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