linux-kernel - Re: [PATCH 2/6] treewide: remove using list iterator after loop body as a ptr

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Message-ID: <CAH8yC8nwp8f3rANhCiiP_Oiw2cjfqCwAgZdTXY9OxtN9Tmm7HA@mail.gmail.com>
Date:   Mon, 28 Feb 2022 16:18:56 -0500
From:   Jeffrey Walton <noloader@...il.com>
To:     James Bottomley <James.Bottomley@...senpartnership.com>
Cc:     Christian König <christian.koenig@....com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
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Subject: Re: [PATCH 2/6] treewide: remove using list iterator after loop body
 as a ptr

On Mon, Feb 28, 2022 at 3:45 PM James Bottomley
<James.Bottomley@...senpartnership.com> wrote:
> ...
> > Just from skimming over the patches to change this and experience
> > with the drivers/subsystems I help to maintain I think the primary
> > pattern looks something like this:
> >
> > list_for_each_entry(entry, head, member) {
> >      if (some_condition_checking(entry))
> >          break;
> > }
> > do_something_with(entry);
>
>
> Actually, we usually have a check to see if the loop found anything,
> but in that case it should something like
>
> if (list_entry_is_head(entry, head, member)) {
>     return with error;
> }
> do_somethin_with(entry);

Borrowing from c++, perhaps an explicit end should be used:

  if (list_entry_not_end(entry))
    do_somethin_with(entry)

It is modelled after c++ and the 'while(begin != end) {}' pattern.

Jeff