From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935379AbZDBHUD (ORCPT ); Thu, 2 Apr 2009 03:20:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933046AbZDBHSq (ORCPT ); Thu, 2 Apr 2009 03:18:46 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:57911 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1765968AbZDBHSp (ORCPT ); Thu, 2 Apr 2009 03:18:45 -0400 Message-ID: <49D46674.9030804@cn.fujitsu.com> Date: Thu, 02 Apr 2009 15:17:08 +0800 From: Lai Jiangshan User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Steven Rostedt CC: Ingo Molnar , Frederic Weisbecker , LKML Subject: [PATCH 4/4] tracing: fix splice return too large Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I got these from strace: splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 16384 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192 I wanted to splice_read 4096 bytes, but it returns 8192 or larger. It is because the return value of tracing_buffers_splice_read() is not include "zero out any left over data" bytes. But tracing_buffers_read() include these bytes, we make them consistent. Signed-off-by: Lai Jiangshan --- diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d101c12..a7ea047 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3408,7 +3408,19 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, int size, i; size_t ret; - 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; + } + + for (i = 0; i < PIPE_BUFFERS && len; i++, len -= PAGE_SIZE) { struct page *page; int r; @@ -3447,7 +3459,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, spd.partial[i].offset = 0; spd.partial[i].private = (unsigned long)ref; spd.nr_pages++; - *ppos += size; + *ppos += PAGE_SIZE; } spd.nr_pages = i;