From: Johan Hovold <johan@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
Alex Elder <elder@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
greybus-dev@lists.linaro.org, linux-staging@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] staging: greybus: Convert uart.c from IDR to XArray
Date: Tue, 31 Aug 2021 10:16:42 +0200 [thread overview]
Message-ID: <YS3laqvwXE9XoAD/@hovoldconsulting.com> (raw)
In-Reply-To: <YSzdtzH1GdZqt66G@casper.infradead.org>
On Mon, Aug 30, 2021 at 02:31:35PM +0100, Matthew Wilcox wrote:
> On Mon, Aug 30, 2021 at 02:33:05PM +0200, Johan Hovold wrote:
> > On Mon, Aug 30, 2021 at 01:16:07PM +0100, Matthew Wilcox wrote:
> > > On Mon, Aug 30, 2021 at 01:52:48PM +0200, Johan Hovold wrote:
> > > > Whether the API is better is debatable. As I said, almost no drivers use
> > > > the new XArray interface, and perhaps partly because the new interface
> > > > isn't as intuitive as has been claimed (e.g. xa_load() instead of
> > > > ida_find()). And IDR/IDA isn't marked/documented as deprecated as far as
> > > > I know.
> > > Why do you think that idr_find() is more intuitive than xa_load()?
> > > The 'find' verb means that you search for something. But it doesn't
> > > search for anything; it just returns the pointer at that index.
> > > 'find' should return the next non-NULL pointer at-or-above a given
> > > index.
> >
> > We're looking up a minor number which may or may not exist. "Find" (or
> > "lookup" or "search") seems to describe this much better than "load"
> > (even if that may better reflect the implementation of XArray).
>
> It's not the _implementation_ that it fits, it's the _idiom_.
> The implementation is a lookup in a trie. The idiom of the XArray
> is that it's a sparse array, and so it's a load.
Ok, but it still stands out in the conversions since it is in no way
obvious that idr_find() should be replaced by xa_load() from just
looking at the diff. You need to look up the interface for that.
> > And no, I would not expect a find implementation to return the next
> > entry if the requested entry does not exist (and neither does idr_find()
> > or radix_tree_lookup()).
>
> Oh dear. You've been corrupted by the bad naming of the IDR functions
> ;-(
Heh. Don't flatter yourself. Just look up any text book on data
structures.
Johan
prev parent reply other threads:[~2021-08-31 8:16 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-29 9:22 [PATCH v4] staging: greybus: Convert uart.c from IDR to XArray Fabio M. De Francesco
2021-08-30 9:12 ` Johan Hovold
2021-08-30 11:10 ` Fabio M. De Francesco
2021-08-30 11:52 ` Johan Hovold
2021-08-30 12:16 ` Matthew Wilcox
2021-08-30 12:33 ` Johan Hovold
2021-08-30 13:16 ` Fabio M. De Francesco
2021-08-30 13:20 ` [greybus-dev] " Alex Elder
2021-08-31 8:07 ` Johan Hovold
2021-08-31 10:42 ` Alex Elder
2021-08-31 11:51 ` Johan Hovold
2021-08-31 11:50 ` Fabio M. De Francesco
2021-08-31 12:18 ` Johan Hovold
2021-09-01 12:09 ` Alex Elder
2021-09-01 13:56 ` Fabio M. De Francesco
2021-09-01 14:29 ` Matthew Wilcox
2021-09-01 15:39 ` Fabio M. De Francesco
2021-08-30 13:31 ` Matthew Wilcox
2021-08-31 8:16 ` Johan Hovold [this message]
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