From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932552AbaFLG5u (ORCPT ); Thu, 12 Jun 2014 02:57:50 -0400 Received: from mail4.hitachi.co.jp ([133.145.228.5]:39930 "EHLO mail4.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932111AbaFLG5t (ORCPT ); Thu, 12 Jun 2014 02:57:49 -0400 Message-ID: <53994F67.9030106@hitachi.com> Date: Thu, 12 Jun 2014 15:57:43 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Namhyung Kim Cc: Steven Rostedt , Josh Poimboeuf , Ingo Molnar , Ananth N Mavinakayanahalli , Linux Kernel Mailing List , "yrl.pp-manager.tt@hitachi.com" Subject: Re: 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> <871tuuad02.fsf@sejong.aot.lge.com> In-Reply-To: <871tuuad02.fsf@sejong.aot.lge.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/06/12 14:54), Namhyung Kim wrote: > 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(). I guessed that was just for speeding up by skipping ftrace_lookup_ip(). (but I'm not sure how much it improves...) Reviewed-by: Masami Hiramatsu However, I'd like to ask Steven his Ack. Thank you, > > 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/ > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com