Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946548AbbGaV2c (ORCPT ); Fri, 31 Jul 2015 17:28:32 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:46612 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752948AbbGaT6V (ORCPT ); Fri, 31 Jul 2015 15:58:21 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, He Kuang , Steven Rostedt Subject: [PATCH 4.1 186/267] tracing: Fix sample output of dynamic arrays Date: Fri, 31 Jul 2015 12:40:37 -0700 Message-Id: <20150731194008.292401675@linuxfoundation.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <20150731194001.933895871@linuxfoundation.org> References: <20150731194001.933895871@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3188 Lines: 82 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Steven Rostedt (Red Hat)" commit d6726c8145290bef950ae2538ea6ae1d96a1944b upstream. He Kuang noticed that the trace event samples for arrays was broken: "The output result of trace_foo_bar event in traceevent samples is wrong. This problem can be reproduced as following: (Build kernel with SAMPLE_TRACE_EVENTS=m) $ insmod trace-events-sample.ko $ echo 1 > /sys/kernel/debug/tracing/events/sample-trace/foo_bar/enable $ cat /sys/kernel/debug/tracing/trace event-sample-980 [000] .... 43.649559: foo_bar: foo hello 21 0x15 BIT1|BIT3|0x10 {0x1,0x6f6f6e53,0xff007970,0xffffffff} Snoopy ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The array length is not right, should be {0x1}. (ffffffff,ffffffff) event-sample-980 [000] .... 44.653827: foo_bar: foo hello 22 0x16 BIT2|BIT3|0x10 {0x1,0x2,0x646e6147,0x666c61,0xffffffff,0xffffffff,0x750aeffe,0x7} ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The array length is not right, should be {0x1,0x2}. Gandalf (ffffffff,ffffffff)" This was caused by an update to have __print_array()'s second parameter be the count of items in the array and not the size of the array. As there is already users of __print_array(), it can not change. But the sample code can and we can also improve on the documentation about __print_array() and __get_dynamic_array_len(). Link: http://lkml.kernel.org/r/1436839171-31527-2-git-send-email-hekuang@huawei.com Fixes: ac01ce1410fc2 ("tracing: Make ftrace_print_array_seq compute buf_len") Reported-by: He Kuang Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- samples/trace_events/trace-events-sample.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/samples/trace_events/trace-events-sample.h +++ b/samples/trace_events/trace-events-sample.h @@ -168,7 +168,10 @@ * * For __dynamic_array(int, foo, bar) use __get_dynamic_array(foo) * Use __get_dynamic_array_len(foo) to get the length of the array - * saved. + * saved. Note, __get_dynamic_array_len() returns the total allocated + * length of the dynamic array; __print_array() expects the second + * parameter to be the number of elements. To get that, the array length + * needs to be divided by the element size. * * For __string(foo, bar) use __get_str(foo) * @@ -288,7 +291,7 @@ TRACE_EVENT(foo_bar, * This prints out the array that is defined by __array in a nice format. */ __print_array(__get_dynamic_array(list), - __get_dynamic_array_len(list), + __get_dynamic_array_len(list) / sizeof(int), sizeof(int)), __get_str(str), __get_bitmask(cpus)) ); -- 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/