From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx192.postini.com [74.125.245.192]) by kanga.kvack.org (Postfix) with SMTP id 2BD876B0044 for ; Fri, 3 Aug 2012 13:59:22 -0400 (EDT) Date: Fri, 3 Aug 2012 10:59:11 -0700 From: Josh Triplett Subject: Re: [RFC 1/4] hashtable: introduce a small and naive hashtable Message-ID: <20120803175911.GA3737@jtriplet-mobl1> References: <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> <501AF555.3050004@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <501AF555.3050004@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Sasha Levin Cc: Tejun Heo , torvalds@linux-foundation.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, paul.gortmaker@windriver.com On Thu, Aug 02, 2012 at 11:47:01PM +0200, Sasha Levin wrote: > 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. ...how strange. The above syntax ought to work, and many other compilers document it as legal syntax (and I thought that C1x's anonymous structs and unions allowed it), but indeed GCC doesn't accept it. Fair enough; looks like consolidating the macro implementations won't actually work. - Josh Triplett -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org