Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764021AbZDHJzc (ORCPT ); Wed, 8 Apr 2009 05:55:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751840AbZDHJzX (ORCPT ); Wed, 8 Apr 2009 05:55:23 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:44813 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751268AbZDHJzW (ORCPT ); Wed, 8 Apr 2009 05:55:22 -0400 Date: Wed, 8 Apr 2009 11:55:09 +0200 From: Ingo Molnar To: Lai Jiangshan Cc: Steven Rostedt , Frederic Weisbecker , LKML Subject: Re: [PATCH 4/4] tracing: fix splice return too large Message-ID: <20090408095509.GA22471@elte.hu> References: <49D46674.9030804@cn.fujitsu.com> <20090403131629.GA8875@elte.hu> <49DC6F01.6030203@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49DC6F01.6030203@cn.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1461 Lines: 45 * Lai Jiangshan wrote: > Ingo Molnar wrote: > > * Lai Jiangshan wrote: > > > >> - for (i = 0; i < PIPE_BUFFERS && len; i++, len -= size) { > >> + if (*ppos & (PAGE_SIZE - 1)) { > >> + WARN_ONCE(1, "Ftrace: previous read must page-align\n"); > >> + return -EINVAL; > >> + } > >> + > >> + if (len & (PAGE_SIZE - 1)) { > >> + WARN_ONCE(1, "Ftrace: splice_read should page-align\n"); > >> + if (len < PAGE_SIZE) > >> + return -EINVAL; > >> + len &= PAGE_MASK; > >> + } > > > > Hm, the fix looks good, but is it a good idea to allow the > > triggering of this message from user-space? > > > > But it is only triggered once. > > If user get content from trace_pipe_raw with non-page-align, the > content is garbage. It's wasting, the kernel disallows it. This > message tell user why he read failed. > > These 4 patches make trace_pipe_raw more robustious and consistent > (read by read(2) and splice). I focus on handling raw ftrace data > in userspace, these raw ftrace data should be trustiness. Ok, agreed. i've applied these four fixes from you to tip:tracing/splice, thanks. Steve: i think they are tracing/urgent material - do you agree? Ingo -- 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/