From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v7 02/24] mm/gup: factor out duplicate code from four
 routines
Date: Thu, 21 Nov 2019 09:03:56 +0100
Message-ID: <20191121080356.GA24784@lst.de>
References: <20191121071354.456618-1-jhubbard@nvidia.com> <20191121071354.456618-3-jhubbard@nvidia.com>
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To: John Hubbard <jhubbard@nvidia.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Al Viro <viro@zeniv.linux.org.uk>, Alex Williamson <alex.williamson@redhat.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= <bjorn.topel@intel.com>, Christoph Hellwig <hch@infradead.org>, Dan Williams <dan.j.williams@intel.com>, Daniel Vetter <daniel@ffwll.ch>, Dave Chinner <david@fromorbit.com>, David Airlie <airlied@linux.ie>, "David S . Miller" <davem@davemloft.net>, Ira Weiny <ira.weiny@intel.com>, Jan Kara <jack@suse.cz>, Jason Gunthorpe <jgg@ziepe.ca>, Jens Axboe <axboe@kernel.dk>, Jonathan Corbet <corbet@lwn.net>, =?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>, Magnus Karlsson <magnus.karlsson@intel.com>, Mauro Carvalho Chehab <mchehab@kernel.org>, Micha
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On Wed, Nov 20, 2019 at 11:13:32PM -0800, John Hubbard wrote:
> There are four locations in gup.c that have a fair amount of code
> duplication. This means that changing one requires making the same
> changes in four places, not to mention reading the same code four
> times, and wondering if there are subtle differences.
> 
> Factor out the common code into static functions, thus reducing the
> overall line count and the code's complexity.
> 
> Also, take the opportunity to slightly improve the efficiency of the
> error cases, by doing a mass subtraction of the refcount, surrounded
> by get_page()/put_page().
> 
> Also, further simplify (slightly), by waiting until the the successful
> end of each routine, to increment *nr.

Any reason for the spurious underscore in the function name?

Otherwise this looks fine and might be a worthwhile cleanup to feed
Andrew for 5.5 independent of the gut of the changes.

Reviewed-by: Christoph Hellwig <hch@lst.de>