From mboxrd@z Thu Jan  1 00:00:00 1970
From: Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 0/2] be more generous with ptrlist repacking
Date: Thu, 17 Nov 2016 09:40:20 -0800
Message-ID: <CA+55aFwYGCD-+GhVLdHedu42cu1RyT+Ko9Dj6-pfTrPv0ZD5Jg@mail.gmail.com>
References: <20161117172559.29417-1-luc.vanoostenryck@gmail.com>
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To: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Sparse Mailing-list <linux-sparse@vger.kernel.org>, Christopher Li <sparse@chrisli.org>

On Thu, Nov 17, 2016 at 9:25 AM, Luc Van Oostenryck
<luc.vanoostenryck@gmail.com> wrote:
> The macros that do the ptrlist walking don't handle empty blocks.

Actually, most of the_do_ handle empty blocks. In particular, the
normal FOR_EACH_PTR() case should handle it just fine.

The exception is, I think:

 - first_ptr_list/last_ptr_list

 - DO_PREPARE/DO_RESET

which just don't walk the pointer block list, they just end up blindly doing

        PTR_ENTRY(list, 0);

for the first entry, or

        list = list->prev;
        PTR_ENTRY(list, list->nr-1);

for the last one.

I suspect they should be fairly easy to update to just walk the list
until they hit a non-empty case (like DO_NEXT() already does, for
example).

              Linus