Date: Wed, 21 Apr 2010 01:43:56 +0200 (CEST)
From: Jiri Kosina <jkosina@suse.cz>
To: Jan Kiszka <jan.kiszka@web.de>
Cc: Jeff Dike <jdike@addtoit.com>, Amerigo Wang <xiyou.wangcong@gmail.com>,
       linux-kernel@vger.kernel.org,
       user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [PATCH 3/5] uml: Fix warning due to missing task_struct
 declaration
In-Reply-To: <4BCDDFBB.40805@web.de>
Message-ID: <alpine.LNX.2.00.1004210143060.7579@pobox.suse.cz>
References: <cover.1271713955.git.jan.kiszka@web.de> <1d97cd7761a1eae73923b1adda4c6915a0647bb3.1271713955.git.jan.kiszka@web.de> <20100420100949.GB5317@cr0.nay.redhat.com> <20100420143016.GB30011@c-98-229-117-200.hsd1.ma.comcast.net>
 <4BCDDFBB.40805@web.de>
User-Agent: Alpine 2.00 (LNX 1167 2008-08-23)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=UTF-8
Content-Transfer-Encoding: 8BIT
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1989
Lines: 48

On Tue, 20 Apr 2010, Jan Kiszka wrote:

> >>> We can't pull in linux/sched.h, so just declare the struct.
> >>>
> >> Did you meet any build error? If yes, please include it.
> > 
> > What does this patch fix, aside from being a bit cleaner?
> 
>   CC      arch/um/sys-i386/elfcore.o
> In file included from /data/linux-2.6/include/linux/elf.h:8,
>                  from /data/linux-2.6/arch/um/sys-i386/elfcore.c:2:
> /data/linux-2.6/arch/um/sys-i386/asm/elf.h:78: warning: ‘struct task_struct’ declared inside parameter list
> /data/linux-2.6/arch/um/sys-i386/asm/elf.h:78: warning: its scope is only this definition or declaration, which is probably not what you want
> 
> I guess not many people build against i386 hosts anymore, so this
> remained widely unnoticed.
> 
> > 
> > If it built before, without having a task_struct declaration, I think
> > that means that the elf_core_copy_fpregs was never used.  The
> > task_struct * in the declaration would become a private task_struct,
> > known only to the declaration.  If the implementation or callers have
> > the regular task_struct, it will be a different one, and the
> > prototypes will conflict due to the different types of the first
> > parameter.
> 
> This is just a forward declaration (that many arch elf header include),
> so no such problem exists.
> 
> BTW, to answer the other question in this thread: We have a circular
> dependency that prevents including sched.h.
> 
> I can add all these information to some v2 of this patch if it is
> required to get this merged. Please let me know.

I have updated the explanation in the changelog and applied the patch. If 
anyone has any objections still, please let me know.

Thanks,

-- 
Jiri Kosina
SUSE Labs, Novell Inc.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/