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Date: Thu, 10 Dec 2015 07:35:40 -0800
From: Christoph Hellwig <hch@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>, Geliang Tang <geliangtang@163.com>,
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Subject: Re: [PATCH 1/4] list: introduce list_is_first()
Message-ID: <20151210153540.GA27533@infradead.org>
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On Thu, Dec 10, 2015 at 09:23:57AM -0600, Josh Poimboeuf wrote:
> Personally I would disagree.  Something like:
> 
>   if (list_is_first(&rq->queuelist, &nd->queue))
> 
> is much more readable to me than:
> 
>   if (rq->queuelist.prev == &nd->queue)
> 
> The first one takes no effort for me -- it's almost English.  While the
> second one takes me a few seconds (and some precious brain cycles) to
> decipher.
> 
> Maybe whether it's readable depends on how many years you've been
> looking at the pattern.  But IMHO we shouldn't make "having x # of years
> staring at kernel code" a prerequisite for being able to read kernel
> code.

I think understanding the list.h semantics is a requirement for writing
(or reading) non-trivial kernel code.