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From: John Baldwin <jhb@freebsd.org>
To: Roman Divacky <rdivacky@freebsd.org>
Date: Fri, 13 Jul 2007 08:21:58 -0400
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Cc: Perforce Change Reviews <perforce@freebsd.org>
Subject: Re: PERFORCE change 122480 for review
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On Monday 02 July 2007 09:10:38 am Roman Divacky wrote:
> On Fri, Jun 29, 2007 at 08:52:06PM -0400, John Baldwin wrote:
> > On Thursday 28 June 2007 08:14:43 am Roman Divacky wrote:
> > > http://perforce.freebsd.org/chv.cgi?CH=122480
> > > 
> > > Change 122480 by rdivacky@rdivacky_witten on 2007/06/28 12:14:14
> > > 
> > > 	vrele AFTER checking the vp for being on non-MPSAFE FS +  some 
indentation
> > > 	problems that caused bad scoping
> > > 	
> > > 	Noticed by: rwatson (again ;) )
> > 
> > Umm, no.  You need Giant for the vrele().  The proper fix is to use the 
> > VFS_*_GIANT() macros and use int variables to know if you need to unlock 
> > Giant or not.
> 
> I dont see an easy and elegant way how to use the VFS_*_GIANT macros. I lock
> the giant in kern_get_at() function and unlock in function that calls this 
one. ie.:
> 
> foo()
> {
>    kern_get_at(...);
>    ...
>    if (VFS_NEEDSGIANT)
>          mtx_unlock(&Giant);
> }
> 
> I need to either propagate the vfslocked value from kern_get_at or lock the 
Giant in the foo()
> function. honestly I dont like either much
> 
> what do you suggest?

I would lock Giant in foo() if you already have the vnode in foo().

-- 
John Baldwin