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From: Andrew Morton <akpm@linux-foundation.org>
To: Pavel Emelyanov <xemul@openvz.org>
Cc: ebiederm@xmission.com, linux-kernel@vger.kernel.org, devel@openvz.org
Subject: Re: [PATCH 1/7][QUOTA] Move sysctl management code under ifdef CONFIG_SYSCTL
Date: Tue, 4 Dec 2007 01:45:49 -0800	[thread overview]
Message-ID: <20071204014549.8fe47f7f.akpm@linux-foundation.org> (raw)
In-Reply-To: <47551E79.6080802@openvz.org>

On Tue, 04 Dec 2007 12:31:37 +0300 Pavel Emelyanov <xemul@openvz.org> wrote:

> Andrew Morton wrote:
> > On Tue, 04 Dec 2007 11:58:30 +0300 Pavel Emelyanov <xemul@openvz.org> wrote:
> > 
> >>>> +#ifdef CONFIG_SYSCTL
> >>>>  	register_sysctl_table(sys_table);
> >>>> +#endif
> >>>>  
> >>>>  	dquot_cachep = kmem_cache_create("dquot",
> >>>>  			sizeof(struct dquot), sizeof(unsigned long) * 4,
> >>> We should avoid the ifdefs around the register_sysctl_table() call.
> >>>
> >>> At present the !CONFIG_SYSCTL implementation of register_sysctl_table() is
> >>> a non-inlined NULL-returning stub.  All we have to do is to inline that stub
> >>> then these ifdefs can go away.
> >> What if some code checks for the return value to be not-NULL? In case
> >> CONFIG_SYSCTL=n this code will always think, that the registration failed.
> > 
> > The stub function should return success?
> 
> Well, I think yes. If some functionality is turned off, then the 
> caller should think that everything is going fine (or he should
> explicitly removes the call to it with some other ifdef). 
> 
> At least this is true for stubs that return the error code, not 
> the pointer. E.g. copy_semundo() always returns success if SYSVIPC 
> is off, or namespaces cloning routines act in a similar way.
> 
> Thus I though, that routines, that return pointers should better
> report that everything is OK (somehow) to reduce the number of 
> "helpers" in the outer code. No?
> 

Dunno.  Returning NULL should be OK.  If anyone is dereferenceing that
pointer with CONFIG_SYSCTL=n then they might need some attention?  

  reply	other threads:[~2007-12-04  9:46 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-30 12:58 [PATCH 0/7] Start using sysctl paths in the core kernel code Pavel Emelyanov
2007-11-30 13:02 ` [PATCH 1/7][QUOTA] Move sysctl management code under ifdef CONFIG_SYSCTL Pavel Emelyanov
2007-12-03 21:38   ` Andrew Morton
2007-12-03 23:32     ` Eric W. Biederman
2007-12-04  8:58     ` Pavel Emelyanov
2007-12-04  9:23       ` Andrew Morton
2007-12-04  9:31         ` Pavel Emelyanov
2007-12-04  9:45           ` Andrew Morton [this message]
2007-12-04 11:40             ` Eric W. Biederman
2007-12-04 11:48               ` Andrew Morton
2007-12-04 11:58                 ` Pavel Emelyanov
2007-12-04 12:48                   ` Eric W. Biederman
2007-11-30 13:04 ` [PATCH 2/7][QUOTA] Use sysctl paths to register tables Pavel Emelyanov
2007-11-30 13:09 ` [PATCH 3/7][SYSVIPC] Use the ctl " Pavel Emelyanov
2007-11-30 13:11 ` [PATCH 4/7][SCHED] " Pavel Emelyanov
2007-11-30 13:13 ` [PATCH 5/7][UTS] " Pavel Emelyanov
2007-11-30 13:16 ` [PATCH 6/7][MQUEUE] Move sysctl management code under ifdef CONFIG_SYSCTL Pavel Emelyanov
2007-11-30 13:18 ` [PATCH 7/7][MQUEUE] Use the ctl paths to register tables Pavel Emelyanov

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