Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752377AbaFLFy4 (ORCPT ); Thu, 12 Jun 2014 01:54:56 -0400 Received: from lgeamrelo01.lge.com ([156.147.1.125]:54195 "EHLO lgeamrelo01.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751134AbaFLFyz (ORCPT ); Thu, 12 Jun 2014 01:54:55 -0400 X-Original-SENDERIP: 10.177.220.181 X-Original-MAILFROM: namhyung@gmail.com From: Namhyung Kim To: Masami Hiramatsu Cc: Steven Rostedt , Josh Poimboeuf , Ingo Molnar , Ananth N Mavinakayanahalli , Linux Kernel Mailing List Subject: Re: [PATCH ftrace/core 2/2] ftrace, kprobes: Support IPMODIFY flag to find IP modify conflict References: <20140610105001.8732.93502.stgit@kbuild-fedora.novalocal> <20140610105014.8732.43086.stgit@kbuild-fedora.novalocal> <1402408435.1676.13.camel@leonhard> <5397B0A1.7060401@hitachi.com> <87tx7rao6p.fsf@sejong.aot.lge.com> <53991E85.70109@hitachi.com> Date: Thu, 12 Jun 2014 14:54:53 +0900 In-Reply-To: <53991E85.70109@hitachi.com> (Masami Hiramatsu's message of "Thu, 12 Jun 2014 12:29:09 +0900") Message-ID: <871tuuad02.fsf@sejong.aot.lge.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 12 Jun 2014 12:29:09 +0900, Masami Hiramatsu wrote: > NO, ftrace_lookup_ip() returns NULL if the hash is empty, so adding > !ftrace_hash_empty() is meaningless :) > > Actually, here I intended to have 3 meanings for the new/old_hash arguments, > - If it is NULL, it hits all > - If it is EMPTY_HASH, it hits nothing > - If it has some entries, it hits those entries. > > And in ftrace.c(__ftrace_hash_rec_update), AFAICS, ops->filter_hash has only > 2 meanings, > - If it is EMPTY_HASH or NULL, it hits all > - If it has some entries, it hits those entries. Then I found an unrelated issue during review. It seems that checking NULL other_hash for the 'all' case in __ftrace_hash_rec_update() is not sufficient. It should check EMPTY_HASH case too, but then it ends up removing the check at all since it can be covered in ftrace_lookup_ip(). Thanks, Namhyung diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 13885590a184..8bd7aa69a479 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1545,7 +1545,7 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops, * Only the filter_hash affects all records. * Update if the record is not in the notrace hash. */ - if (!other_hash || !ftrace_lookup_ip(other_hash, rec->ip)) + if (!ftrace_lookup_ip(other_hash, rec->ip)) match = 1; } else { in_hash = !!ftrace_lookup_ip(hash, rec->ip); -- 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/