From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f170.google.com (mail-io0-f170.google.com [209.85.223.170]) by kanga.kvack.org (Postfix) with ESMTP id 5F2D76B0253 for ; Thu, 3 Dec 2015 14:06:17 -0500 (EST) Received: by ioc74 with SMTP id 74so91344465ioc.2 for ; Thu, 03 Dec 2015 11:06:17 -0800 (PST) Received: from smtprelay.hostedemail.com (smtprelay0055.hostedemail.com. [216.40.44.55]) by mx.google.com with ESMTPS id l2si403807igv.8.2015.12.03.11.06.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 03 Dec 2015 11:06:16 -0800 (PST) Date: Thu, 3 Dec 2015 14:06:14 -0500 From: Steven Rostedt Subject: Re: [PATCH V2 2/7] mm/gup: add gup trace points Message-ID: <20151203140614.75f49aad@gandalf.local.home> In-Reply-To: <56608BA2.2050300@linaro.org> References: <1449096813-22436-1-git-send-email-yang.shi@linaro.org> <1449096813-22436-3-git-send-email-yang.shi@linaro.org> <565F8092.7000001@intel.com> <20151202231348.7058d6e2@grimm.local.home> <56608BA2.2050300@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "Shi, Yang" Cc: Dave Hansen , akpm@linux-foundation.org, mingo@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linaro-kernel@lists.linaro.org On Thu, 03 Dec 2015 10:36:18 -0800 "Shi, Yang" wrote: > > called directly that calls these functions internally and the tracepoint > > can trap the return value. > > This will incur more changes in other subsystems (futex, kvm, etc), I'm > not sure if it is worth making such changes to get return value. No, it wouldn't require any changes outside of this. -long __get_user_pages(..) +static long __get_user_pages_internal(..) { [..] } + +long __get_user_pages(..) +{ + long ret; + ret = __get_user_pages_internal(..); + trace_get_user_pages(.., ret) +} > > > I can probably make function_graph tracer give return values, although > > it will give a return value for void functions as well. And it may give > > long long returns for int returns that may have bogus data in the > > higher bits. > > If the return value requirement is not limited to gup, the approach > sounds more reasonable. > Others have asked about it. Maybe I should do it. -- Steve -- 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