svn commit: r348300 - head/sys/ufs/ffs

[Kirk McKusick]

> Date: Mon, 27 May 2019 16:15:00 -0400
> From: Mark Johnston <markj at freebsd.org>
> To: Kirk McKusick <mckusick at freebsd.org>
> Cc: src-committers at freebsd.org, svn-src-all at freebsd.org,
>         svn-src-head at freebsd.org
> Subject: Re: svn commit: r348300 - head/sys/ufs/ffs
> 
> On Mon, May 27, 2019 at 06:22:44AM +0000, Kirk McKusick wrote:
>> Author: mckusick
>> Date: Mon May 27 06:22:43 2019
>> New Revision: 348300
>> URL: https://svnweb.freebsd.org/changeset/base/348300
>> 
>> Log:
>>   Add function name and line number debugging information to softupdates
>>   worklist structures to help track their movement between work lists.
>>   No functional change to the operation of soft updates intended.
>> 
>> Modified:
>>   head/sys/ufs/ffs/ffs_softdep.c
>>   head/sys/ufs/ffs/softdep.h
>> 
>> [...]
>> Modified: head/sys/ufs/ffs/softdep.h
>> ==============================================================================
>> --- head/sys/ufs/ffs/softdep.h	Mon May 27 04:20:31 2019	(r348299)
>> +++ head/sys/ufs/ffs/softdep.h	Mon May 27 06:22:43 2019	(r348300)
>> @@ -213,6 +213,10 @@ struct worklist {
>>  	struct mount		*wk_mp;		/* Mount we live in */
>>  	unsigned int		wk_type:8,	/* type of request */
>>  				wk_state:24;	/* state flags */
>> +#ifdef DEBUG
>> +	const char		*wk_func;	/* func where added / removed */
>> +	int			wk_line;	/* line where added / removed */
>> +#endif
>>  };
>>  #define	WK_DATA(wk) ((void *)(wk))
>>  #define	WK_PAGEDEP(wk) ((struct pagedep *)(wk))
> 
> ffs_softdep.c defines DEBUG, while ffs_alloc.c (which includes
> softdep.h) does not.  A result of this is that the kernel's type info
> used by DTrace contains two different definitions of struct worklist,
> which has a sort of snowball effect since we end up with two definitions
> of each structure containing a struct worklist *, and so on.
> 
> Could we turn DEBUG into a proper kernel configuration option so that
> it's defined consistently everywhere, or just use INVARIANTS/DIAGNOSTIC
> instead?  I am happy to do the work if we can agree on a direction.
> 
> DEBUG is used only in the SU, snapshot and the block allocation code.
> In ffs_alloc.c it is used to enable some debug printfs (which are
> themselves conditionalized on a sysctl var).  It is used similarly in
> ffs_snapshot.c.  In ffs_softdep.c (which also has SUJ_DEBUG) it enables
> some consistency checking.  INVARIANTS seems to me like a reasonable
> option to use in ffs_softdep.c, and perhaps the others as well.

Thanks for pointing out this problem. DEBUG is left over from the CSRG
days (1980's :-) and should have been purged decades ago.

I have converted its use in ffs_snapshot.c and ffs_alloc.c to DIAGNOSTIC.
In ffs_softdep.c I have converted DEBUG and SUJ_DEBUG to INVARIANTS.

	Kirk