On Thu, Dec 10, 2015 at 08:10:34AM -0700, Jens Axboe wrote:
On 12/10/2015 07:17 AM, Geliang Tang wrote:
We already have list_is_last(), it makes sense to also add
list_is_first() for consistency. This list utility function
to check for first element in a list.
Honestly, I think we already have way too many of these kind of helpers.
IMHO they don't really help, they hurt readability. You should know how the
list works anyway, and if you do, then it's a no-brainer what's first and
last. If you don't, then you are bound to screw up in other ways.
Just my 2 cents.
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
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