Date: Wed, 19 Oct 2016 09:32:00 +0200
From: Jan Kara <jack@suse.cz>
To: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Jan Kara <jack@suse.cz>, linux-mm@kvack.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Rik van Riel <riel@redhat.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        adi-buildroot-devel@lists.sourceforge.net, ceph-devel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,
        kvm@vger.kernel.org, linux-alpha@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-cris-kernel@axis.com,
        linux-fbdev@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org, linux-mips@linux-mips.org,
        linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org,
        linux-samsung-soc@vger.kernel.org, linux-scsi@vger.kernel.org,
        linux-security-module@vger.kernel.org, linux-sh@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org,
        sparclinux@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH 04/10] mm: replace get_user_pages_locked() write/force
 parameters with gup_flags
Message-ID: <20161019073200.GK29967@quack2.suse.cz>
References: <20161013002020.3062-1-lstoakes@gmail.com>
 <20161013002020.3062-5-lstoakes@gmail.com>
 <20161018125425.GD29967@quack2.suse.cz>
 <20161018135609.GA30025@lucifer>
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On Tue 18-10-16 14:56:09, Lorenzo Stoakes wrote:
> On Tue, Oct 18, 2016 at 02:54:25PM +0200, Jan Kara wrote:
> > > @@ -1282,7 +1282,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
> > >  			    int write, int force, struct page **pages,
> > >  			    struct vm_area_struct **vmas);
> > >  long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
> > > -		    int write, int force, struct page **pages, int *locked);
> > > +		    unsigned int gup_flags, struct page **pages, int *locked);
> >
> > Hum, the prototype is inconsistent with e.g. __get_user_pages_unlocked()
> > where gup_flags come after **pages argument. Actually it makes more sense
> > to have it before **pages so that input arguments come first and output
> > arguments second but I don't care that much. But it definitely should be
> > consistent...
> 
> It was difficult to decide quite how to arrange parameters as there was
> inconsitency with regards to parameter ordering already - for example
> __get_user_pages() places its flags argument before pages whereas, as you note,
> __get_user_pages_unlocked() puts them afterwards.
> 
> I ended up compromising by trying to match the existing ordering of the function
> as much as I could by replacing write, force pairs with gup_flags in the same
> location (with the exception of get_user_pages_unlocked() which I felt should
> match __get_user_pages_unlocked() in signature) or if there was already a
> gup_flags parameter as in the case of __get_user_pages_unlocked() I simply
> removed the write, force pair and left the flags as the last parameter.
> 
> I am happy to rearrange parameters as needed, however I am not sure if it'd be
> worthwhile for me to do so (I am keen to try to avoid adding too much noise here
> :)
> 
> If we were to rearrange parameters for consistency I'd suggest adjusting
> __get_user_pages_unlocked() to put gup_flags before pages and do the same with
> get_user_pages_unlocked(), let me know what you think.

Yeah, ok. If the inconsistency is already there, just leave it for now.

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