Date:   Fri, 17 Feb 2023 19:45:31 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Danilo Krummrich <dakr@redhat.com>
Cc:     airlied@gmail.com, daniel@ffwll.ch, tzimmermann@suse.de,
        mripard@kernel.org, corbet@lwn.net, christian.koenig@amd.com,
        bskeggs@redhat.com, Liam.Howlett@oracle.com,
        matthew.brost@intel.com, boris.brezillon@collabora.com,
        alexdeucher@gmail.com, ogabbay@kernel.org, bagasdotme@gmail.com,
        jason@jlekstrand.net, dri-devel@lists.freedesktop.org,
        nouveau@lists.freedesktop.org, linux-doc@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH drm-next v2 03/16] maple_tree: split up MA_STATE() macro
Message-ID: <Y+/ZW/8WXzrkQnUT@casper.infradead.org>
References: <20230217134422.14116-1-dakr@redhat.com>
 <20230217134422.14116-4-dakr@redhat.com>
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On Fri, Feb 17, 2023 at 02:44:09PM +0100, Danilo Krummrich wrote:
> \#define SAMPLE_ITER(name, __mgr) \
> 	struct sample_iter name = { \
> 		.mas = __MA_STATE(&(__mgr)->mt, 0, 0),

This is usually called MA_STATE_INIT()

> #define sample_iter_for_each_range(it__, start__, end__) \
> 	for ((it__).mas.index = start__, (it__).entry = mas_find(&(it__).mas, end__ - 1); \
> 	     (it__).entry; (it__).entry = mas_find(&(it__).mas, end__ - 1))

This is a bad iterator design.  It's usually best to do this:

	struct sample *sample;
	SAMPLE_ITERATOR(si, min);

	sample_iter_for_each(&si, sample, max) {
		frob(mgr, sample);
	}

I don't mind splitting apart MA_STATE_INIT from MA_STATE, and if you
do that, we can also use it in VMA_ITERATOR.