From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753396AbcFGICn (ORCPT ); Tue, 7 Jun 2016 04:02:43 -0400 Received: from mail.kernel.org ([198.145.29.136]:43299 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751294AbcFGICj (ORCPT ); Tue, 7 Jun 2016 04:02:39 -0400 Date: Tue, 7 Jun 2016 17:02:32 +0900 From: Masami Hiramatsu To: Omar Sandoval Cc: Steven Rostedt , Ingo Molnar , Namhyung Kim , linux-kernel@vger.kernel.org, kernel-team@fb.com, Omar Sandoval Subject: Re: [PATCH v2 3/3] tracing: make "string" the default type for [ku]probe event $comm Message-Id: <20160607170232.575878d689a656f53d357e22@kernel.org> In-Reply-To: References: X-Mailer: Sylpheed 3.4.3 (GTK+ 2.24.28; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2 Jun 2016 18:11:03 -0700 Omar Sandoval wrote: > From: Omar Sandoval > > You'd only ever want $comm as a string, but the default is still u64. > Push the type parsing later so we can decide based on the actual > fetcharg and make "string" the default for $comm. Hmm, at this moment, I'd rather like a small hack in traceprobe_parse_probe_arg() as like below: --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -522,6 +522,12 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size, arg[t - parg->comm] = '\0'; t++; } + /* + * The default type of "$comm" should be a string, and it must not + * be dereferred + */ + if (!t && strcmp("$comm", arg)) + t = "string"; parg->type = find_fetch_type(t, ftbl); if (!parg->type) { pr_info("Unsupported type: %s\n", t); This is not general, but easy to review :) Thank you, -- Masami Hiramatsu