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Date: Thu, 02 Aug 2012 23:47:01 +0200
From: Sasha Levin <levinsasha928@gmail.com>
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To: Josh Triplett <josh@joshtriplett.org>
CC: Tejun Heo <tj@kernel.org>, torvalds@linux-foundation.org,
        akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, paul.gortmaker@windriver.com
Subject: Re: [RFC 1/4] hashtable: introduce a small and naive hashtable
References: <5019B0B4.1090102@gmail.com> <20120801224556.GF15477@google.com> <501A4FC1.8040907@gmail.com> <20120802103244.GA23318@leaf> <501A633B.3010509@gmail.com> <501A7AD3.7000008@gmail.com> <20120802161556.GA25572@leaf> <501AAF47.3090708@gmail.com> <20120802174457.GA6251@jtriplet-mobl1> <501ABEE2.10007@gmail.com> <20120802204157.GB7916@jtriplet-mobl1>
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On 08/02/2012 10:41 PM, Josh Triplett wrote:
> On Thu, Aug 02, 2012 at 07:54:42PM +0200, Sasha Levin wrote:
>> /* I've "preprocessed" the DEFINE macro below */
>> union {
>> 	struct hash_table table;
>> 	struct {
>> 		size_t bits;
>> 		struct hlist_head buckets[32];
>> 	}
>> } my_hashtable;
> 
> That expansion doesn't match the macros.  Using the most recent
> definitions of DEFINE_HASHTABLE and DEFINE_STATIC_HASHTABLE from above,
> the definition would look something like this:
> 
> static union {
> 	struct hash_table my_hashtable;
> 	struct {
> 		size_t bits;
> 		struct hlist_head buckets[1 << 5];
> 	} __my_hashtable;
> } = { .my_hashtable.bits = 5 };

It's different because I don't think you can do what you did above with global variables.

You won't be defining any instances of that anonymous struct, so my_hashtable won't exist anywhere.