Date: Mon, 26 Aug 2013 16:21:31 +0200 From: Andre Oppermann <andre@freebsd.org> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r254805 - head/sys/sys Message-ID: <521B646B.7080209@freebsd.org> In-Reply-To: <20130826110007.GR4574@FreeBSD.org> References: <201308241958.r7OJwaxV031368@svn.freebsd.org> <20130826110007.GR4574@FreeBSD.org>
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On 26.08.2013 13:00, Gleb Smirnoff wrote: > On Sat, Aug 24, 2013 at 07:58:36PM +0000, Andre Oppermann wrote: > A> Author: andre > A> Date: Sat Aug 24 19:58:36 2013 > A> New Revision: 254805 > A> URL: http://svnweb.freebsd.org/changeset/base/254805 > A> > A> Log: > A> Add mtodo(m, o) macro taking an additional offset into the mbuf data section. > A> > A> Sponsored by: The FreeBSD Foundation > A> > A> Modified: > A> head/sys/sys/mbuf.h > A> > A> Modified: head/sys/sys/mbuf.h > A> ============================================================================== > A> --- head/sys/sys/mbuf.h Sat Aug 24 19:51:18 2013 (r254804) > A> +++ head/sys/sys/mbuf.h Sat Aug 24 19:58:36 2013 (r254805) > A> @@ -67,8 +67,10 @@ > A> * type: > A> * > A> * mtod(m, t) -- Convert mbuf pointer to data pointer of correct type. > A> + * mtodo(m, o) -- Same as above but with offset 'o' into data. > A> */ > A> #define mtod(m, t) ((t)((m)->m_data)) > A> +#define mtodo(m, o) ((void *)(((m)->m_data) + (o))) > > IMO, having a typecast would be better. Then mtodo() would be really same as > mtod(), as stated in comment. There was a big discussion about 10 month back when I did this change in my tcp_workqueue branch with the typecast in. The conclusion was that a typecast is really not necessary and only causes one to type a lot more for the compiler to throw away anyway. But yes, the comment isn't perfect in that sense. -- Andre
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