From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathieu Desnoyers Subject: Re: [RFC patch 08/18] cnt32_to_63 should use smp_rmb() Date: Fri, 7 Nov 2008 13:00:41 -0500 Message-ID: <20081107180041.GG22134@Krystal> References: <20081107003816.9b0f947a.akpm@linux-foundation.org> <20081107052336.652868737@polymtl.ca> <20081107053349.861709786@polymtl.ca> <20081106220530.5b0e3a96.akpm@linux-foundation.org> <25363.1226056819@redhat.com> <8189.1226074915@redhat.com> <8509.1226077800@redhat.com> <20081107092643.0bd9bb4e.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from tomts10-srv.bellnexxia.net ([209.226.175.54]:62084 "EHLO tomts10-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752580AbYKGSAn (ORCPT ); Fri, 7 Nov 2008 13:00:43 -0500 Content-Disposition: inline In-Reply-To: <20081107092643.0bd9bb4e.akpm@linux-foundation.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Andrew Morton Cc: David Howells , Nicolas Pitre , Linus Torvalds , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, Ralf Baechle , benh@kernel.crashing.org, paulus@samba.org, David Miller , Ingo Molnar , Thomas Gleixner , Steven Rostedt , linux-arch@vger.kernel.org * Andrew Morton (akpm@linux-foundation.org) wrote: > On Fri, 07 Nov 2008 17:10:00 +0000 David Howells wrote: > > > > > Andrew Morton wrote: > > > > > I'd expect it to behave in the same way as it would if the function was > > > implemented out-of-line. > > > > > > But it occurs to me that the modrobe-doesnt-work thing would happen if > > > the function _is_ inlined anyway, so we won't be doing that. > > > > > > Whatever. Killing this many puppies because gcc may do something so > > > bizarrely wrong isn't justifiable. > > > > With gcc, you get one instance of the static variable from inside a static > > (inline or outofline) function per .o file that invokes it, and these do not > > merge even though they're common symbols. I asked around and the opinion > > seems to be that this is correct C. I suppose it's the equivalent of cutting > > and pasting a function between several files - why should the compiler assume > > it's the same function in each? > > > > OK, thanks, I guess that makes sense. For static inline. I wonder if > `extern inline' or plain old `inline' should change it. > > It's one of those things I hope I never need to know about, but perhaps > we do somewhere have static storage in an inline. Wouldn't surprise > me, and I bet that if we do, it's a bug. Tracepoints actually use that. It could be changed so they use : DECLARE_TRACE() (in include/trace/group.h) DEFINE_TRACE() (in the appropriate kernel c file) trace_somename(); (in the code) instead. That would actually make more sense and remove the need for multiple declarations when the same tracepoint name is used in many spots (this is a problem kmemtrace has, it generates a lot of tracepoint declarations). Mathieu -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68