From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752329AbcEVKsb (ORCPT ); Sun, 22 May 2016 06:48:31 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:40772 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752054AbcEVKsa (ORCPT ); Sun, 22 May 2016 06:48:30 -0400 Date: Sun, 22 May 2016 12:48:27 +0200 From: Peter Zijlstra To: Alexey Dobriyan Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Paul McKenney Subject: Re: [PATCH] seqlock: fix raw_read_seqcount_latch() Message-ID: <20160522104827.GP3193@twins.programming.kicks-ass.net> References: <20160521201448.GA7429@p183.telecom.by> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160521201448.GA7429@p183.telecom.by> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 21, 2016 at 11:14:49PM +0300, Alexey Dobriyan wrote: > lockless_dereference() is supposed to take pointer not integer. Urgh :/ Is there any way we can make lockless_dereference() issue a warning if we don't feed it a pointer? Would something like so work? All pointer types should silently cast to void * while integer (and others) should refuse to. diff --git a/include/linux/compiler.h b/include/linux/compiler.h index b5ff9881bef8..8886de704d33 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -544,6 +544,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s */ #define lockless_dereference(p) \ ({ \ + __maybe_unused void * _________p2 = p; \ typeof(p) _________p1 = READ_ONCE(p); \ smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ (_________p1); \