The goal here is to replace the head of a existing list pointed to by
'list' with a new head pointed to by 'nlist'.
First there is a memcpy that copies the contents of list to nlist then
this macro is called.
The macro makes sure that if the old head was empty then INIT_LIST_HEAD
the 'nlist', if not then make sure that the nodes before and after the
head now correclty point to nlist instead of list.
regards
shobhit
> ---------- Forwarded message ----------
> From: Christoph Hellwig <[EMAIL PROTECTED]>
> Date: Wed, 30 Mar 2005 12:14:39 +0100
> Subject: Re: [PATCH] Pageset Localization V2
> To: Christoph Lameter <[EMAIL PROTECTED]>
> Cc: Manfred Spraul <[EMAIL PROTECTED]>, Andrew Morton
> <[EMAIL PROTECTED]>, linux-kernel@vger.kernel.org,
> linux-ia64@vger.kernel.org, [EMAIL PROTECTED], [EMAIL PROTECTED]
>
>
> > +#define MAKE_LIST(list, nlist) \
> > + do { \
> > + if(list_empty(&list)) \
> > + INIT_LIST_HEAD(nlist); \
> > + else { nlist->next->prev = nlist; \
> > + nlist->prev->next = nlist; \
> > + } \
> > + }while(0)
>
> This is horrible. Where are the nlist pointers supposed to point to?
> What's so magic you need the INIT_LIST_HEAD only conditionally?
>
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