Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754053AbaDVIYm (ORCPT ); Tue, 22 Apr 2014 04:24:42 -0400 Received: from mail-qc0-f169.google.com ([209.85.216.169]:49967 "EHLO mail-qc0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752384AbaDVIYe (ORCPT ); Tue, 22 Apr 2014 04:24:34 -0400 MIME-Version: 1.0 In-Reply-To: <20140421204835.GB22181@amd.pavel.ucw.cz> References: <1397824031-4892-1-git-send-email-lftan@altera.com> <1397824031-4892-13-git-send-email-lftan@altera.com> <20140419160947.GA27776@amd.pavel.ucw.cz> <20140421204835.GB22181@amd.pavel.ucw.cz> Date: Tue, 22 Apr 2014 16:24:33 +0800 X-Google-Sender-Auth: 7BrZIvRXsuiRABeCOUJFcpPOWA8 Message-ID: Subject: Re: [PATCH 16/28] nios2: System calls handling From: Ley Foon Tan To: Pavel Machek Cc: Richard Weinberger , Linux-Arch , LKML , "linux-doc@vger.kernel.org" , cltang@codesourcery.com, Michael Kerrisk-manpages Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 22, 2014 at 4:48 AM, Pavel Machek wrote: >> >>> +/* sys_cacheflush -- flush the processor cache. */ >> >>> +asmlinkage int sys_cacheflush(unsigned long addr, unsigned long len, >> >>> + unsigned int op) >> >>> +{ >> >>> + struct vm_area_struct *vma; >> >>> + >> >>> + if (len == 0) >> >>> + return 0; >> >> >> >> op is being ignored? You should remove it... or if (op) return -EINVAL >> >> if you want future extensions. >> > Yes, op argument is being ignored. Okay, will add the return -EINVAL >> > if op is non-zero. >> >> Be careful. If existing applications already use this and maybe pass a >> dummy value >> to it you break them. > > Well.. of course, but passing ignored integer to syscall, that can be > never used is beyond ugly. NAK-level ugly. > > If it is so, you can never ever use the argument, and might as well > remove it (depending on your calling convention, it should not break > anything.) > I'm prefer to keep the calling convention here for future use and add the op checking here. This prevent us to update toolchain if we plan to add in op option later. Regards Ley Foon -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/