linux-kernel - Re: [PATCH 3/4] infiniband/mm: convert to the new put_user

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Date:   Wed, 3 Oct 2018 18:27:58 +0200
From:   Jan Kara <jack@...e.cz>
To:     John Hubbard <jhubbard@...dia.com>
Cc:     Jason Gunthorpe <jgg@...pe.ca>, john.hubbard@...il.com,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...nel.org>,
        Christopher Lameter <cl@...ux.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Jan Kara <jack@...e.cz>, Al Viro <viro@...iv.linux.org.uk>,
        linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>,
        linux-rdma <linux-rdma@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org, Doug Ledford <dledford@...hat.com>,
        Mike Marciniszyn <mike.marciniszyn@...el.com>,
        Dennis Dalessandro <dennis.dalessandro@...el.com>,
        Christian Benvenuti <benve@...co.com>
Subject: Re: [PATCH 3/4] infiniband/mm: convert to the new put_user_page()
 call

On Fri 28-09-18 20:12:33, John Hubbard wrote:
>  static inline void release_user_pages(struct page **pages,
> -                                     unsigned long npages)
> +                                     unsigned long npages,
> +                                     bool set_dirty)
>  {
> -       while (npages)
> -               put_user_page(pages[--npages]);
> +       if (set_dirty)
> +               release_user_pages_dirty(pages, npages);
> +       else
> +               release_user_pages_basic(pages, npages);
> +}

Is there a good reason to have this with set_dirty argument? Generally bool
arguments are not great for readability (or greppability for that matter).
Also in this case callers can just as easily do:
	if (set_dirty)
		release_user_pages_dirty(...);
	else
		release_user_pages(...);

And furthermore it makes the code author think more whether he needs
set_page_dirty() or set_page_dirty_lock(), rather than just passing 'true'
and hoping the function magically does the right thing for him.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR