Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753338AbcCGRFn (ORCPT ); Mon, 7 Mar 2016 12:05:43 -0500 Received: from mx2.suse.de ([195.135.220.15]:60540 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753289AbcCGRFf (ORCPT ); Mon, 7 Mar 2016 12:05:35 -0500 Date: Mon, 7 Mar 2016 18:05:32 +0100 (CET) From: Jiri Kosina X-X-Sender: jkosina@pobox.suse.cz To: Alan Stern cc: Sedat Dilek , Steven Rostedt , Tejun Heo , Lai Jiangshan , Benjamin Tissoires , Paul McKenney , Andy Lutomirski , LKML , USB list , Greg Kroah-Hartman , Peter Zijlstra , Ingo Molnar Subject: Re: [PATCH] usbhid: Fix lockdep unannotated irqs-off warning In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1014 Lines: 29 On Mon, 7 Mar 2016, Alan Stern wrote: > > 319: 9c pushfq > > 31a: 41 5c pop %r12 > > 31c: 48 89 df mov %rbx,%rdi > > 31f: e8 00 00 00 00 callq 324 > > 324: 41 54 push %r12 > > 326: 9d popfq > > spin_unlock_irq(&usbhid->lock); while attempting to preserve the Z > flag. The problem is that this code sequence will also preserve the > Interrupt Flag! You are right Alan, thanks a lot, for reason I could not understand I completely missed the pushf/popf last time I was looking at the generated assembly! OK, a little bit of googling revealed related discussion on LLVM mailinglist: http://lists.llvm.org/pipermail/llvm-dev/2015-July/088780.html Seems like it has been reported already, but noone dared to fix it yet. This basically makes LLVM unusable for compiling the kernel. -- Jiri Kosina SUSE Labs