From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F068C433B4 for ; Thu, 13 May 2021 20:24:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9DF6613E9 for ; Thu, 13 May 2021 20:24:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232832AbhEMUZg (ORCPT ); Thu, 13 May 2021 16:25:36 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:40099 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232805AbhEMUZf (ORCPT ); Thu, 13 May 2021 16:25:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620937465; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ksER9Zeo8ZqIFysycLmXjmnFf6PSPfo6EBdkip46x2o=; b=dUtndAcNvtZJWKQuzzh8PPlt3akh9OrBdqzbMaoCeQPqbM518COrup1pteTsLZbbXwX0PM z52D/0FrZmoMhgZXH7j1QO/mt1Ijhvkhp942CsTQgggRUU0BhWIcALE4ECrGod67PTG/sC Eh2LGEIx3I32ATC/ml6+e29Fnr2oy24= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-502-tlK80T5dOCSi6fCs_FO1ew-1; Thu, 13 May 2021 16:24:22 -0400 X-MC-Unique: tlK80T5dOCSi6fCs_FO1ew-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DB3E4803622; Thu, 13 May 2021 20:24:21 +0000 (UTC) Received: from krava (unknown [10.40.192.9]) by smtp.corp.redhat.com (Postfix) with SMTP id D98445D736; Thu, 13 May 2021 20:24:20 +0000 (UTC) Date: Thu, 13 May 2021 22:24:19 +0200 From: Jiri Olsa To: Steven Rostedt Cc: LKML , Ingo Molnar , Andrew Morton Subject: Re: [PATCH] ftrace: Handle commands when closing set_ftrace_filter file Message-ID: References: <20210505104818.24358ef7@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210505104818.24358ef7@gandalf.local.home> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 05, 2021 at 10:48:18AM -0400, Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" > > # echo switch_mm:traceoff > /sys/kernel/tracing/set_ftrace_filter > > will cause switch_mm to stop tracing by the traceoff command. > > # echo -n switch_mm:traceoff > /sys/kernel/tracing/set_ftrace_filter > > does nothing. > > The reason is that the parsing in the write function only processes > commands if it finished parsing (there is white space written after the > command). That's to handle: > > write(fd, "switch_mm:", 10); > write(fd, "traceoff", 8); > > cases, where the command is broken over multiple writes. > > The problem is if the file descriptor is closed, then the write call is > not processed, and the command needs to be processed in the release code. > The release code can handle matching of functions, but does not handle > commands. > > Cc: stable@vger.kernel.org > Fixes: eda1e32855656 ("tracing: handle broken names in ftrace filter") nice, breaking kernel since 2009.. I'll put that on t-shirt ;-) I saw the patch got already merged, FWIW: Acked-by: Jiri Olsa jirka > Signed-off-by: Steven Rostedt (VMware) > --- > kernel/trace/ftrace.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 057e962ca5ce..c57508445faa 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -5591,7 +5591,10 @@ int ftrace_regex_release(struct inode *inode, struct file *file) > > parser = &iter->parser; > if (trace_parser_loaded(parser)) { > - ftrace_match_records(iter->hash, parser->buffer, parser->idx); > + int enable = !(iter->flags & FTRACE_ITER_NOTRACE); > + > + ftrace_process_regex(iter, parser->buffer, > + parser->idx, enable); > } > > trace_parser_put(parser); > -- > 2.29.2 >