Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753573AbZIPPjx (ORCPT ); Wed, 16 Sep 2009 11:39:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752584AbZIPPjv (ORCPT ); Wed, 16 Sep 2009 11:39:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7878 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752267AbZIPPjv (ORCPT ); Wed, 16 Sep 2009 11:39:51 -0400 Message-ID: <4AB1077F.6020107@redhat.com> Date: Wed, 16 Sep 2009 11:42:55 -0400 From: Masami Hiramatsu User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.1) Gecko/20090814 Fedora/3.0-2.6.b3.fc11 Thunderbird/3.0b3 MIME-Version: 1.0 To: rostedt@goodmis.org, Frederic Weisbecker CC: Ingo Molnar , lkml , systemtap , DLE , Jim Keniston , Ananth N Mavinakayanahalli , Andi Kleen , Christoph Hellwig , "Frank Ch. Eigler" , "H. Peter Anvin" , Jason Baron , "K.Prasad" , Lai Jiangshan , Li Zefan , Peter Zijlstra , Srikar Dronamraju , Tom Zanussi Subject: [PATCH tracing/kprobes 2/6] ftrace: Fix trace_add_event_call() to initialize list take 2 References: <20090914204847.18779.69409.stgit@dhcp-100-2-132.bos.redhat.com> <20090914204904.18779.59422.stgit@dhcp-100-2-132.bos.redhat.com> <1253058681.20020.147.camel@gandalf.stny.rr.com> <4AB0F366.6080000@redhat.com> <1253111371.20020.198.camel@gandalf.stny.rr.com> In-Reply-To: <1253111371.20020.198.camel@gandalf.stny.rr.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 Content-Length: 4905 Lines: 156 Steven Rostedt wrote: > On Wed, 2009-09-16 at 10:17 -0400, Masami Hiramatsu wrote: >> Steven Rostedt wrote: > >>>> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c >>>> index ba34920..38e82a5 100644 >>>> --- a/kernel/trace/trace_events.c >>>> +++ b/kernel/trace/trace_events.c >>>> @@ -1009,10 +1009,14 @@ static int __trace_add_event_call(struct ftrace_event_call *call) >>>> if (!d_events) >>>> return -ENOENT; >>>> >>>> + INIT_LIST_HEAD(&call->list); >>> >>> The INIT_LIST_HEAD is not needed here. The list_add will assign it. >> >> Without initializing it, list debugging code warns always :-) >> Please see, __list_add()@lib/list_debug.c > > /me looks > > from: include/linux/list.h > > static inline void list_add(struct list_head *new, struct list_head *head) > { > __list_add(new, head, head->next); > } > > from: lib/list_debug.c > > void __list_add(struct list_head *new, > struct list_head *prev, > struct list_head *next) > { > WARN(next->prev != prev, > "list_add corruption. next->prev should be " > "prev (%p), but was %p. (next=%p).\n", > prev, next->prev, next); > WARN(prev->next != next, > "list_add corruption. prev->next should be " > "next (%p), but was %p. (prev=%p).\n", > next, prev->next, prev); > next->prev = new; > new->next = next; > new->prev = prev; > prev->next = new; > } > > What you pass in is: > > list_add(&call->list,&ftrace_events); > > new =&call->list; > prev =&ftrace_events->prev; > next =&ftrace_events->next; > > The above code never tests "new". The INIT_LIST_HEAD is useless. Oh, I see, I misunderstood. Thank you for pointing it out. :) Here, I updated the patch. --- ftrace: Fix trace_add_event_call() to initialize list From: Masami Hiramatsu Handle failuer path in trace_add_event_call() for fixing below bug which occurred when I tried to add invalid event twice. Could not create debugfs 'kmalloc' directory Failed to register kprobe event: kmalloc Faild to register probe event(-1) ------------[ cut here ]------------ WARNING: at /home/mhiramat/ksrc/random-tracing/lib/list_debug.c:26 __list_add+0x27/0x5c() Hardware name: list_add corruption. next->prev should be prev (c07d78cc), but was 00001000. (next=d854236c). Modules linked in: sunrpc uinput virtio_net virtio_balloon i2c_piix4 pcspkr i2c_core virtio_blk virtio_pci virtio_ring virtio [last unloaded: scsi_wait_scan] Pid: 1394, comm: tee Not tainted 2.6.31-rc9 #51 Call Trace: [] warn_slowpath_common+0x65/0x7c [] ? __list_add+0x27/0x5c [] warn_slowpath_fmt+0x24/0x27 [] __list_add+0x27/0x5c [] list_add+0xa/0xc [] trace_add_event_call+0x60/0x97 [] command_trace_probe+0x42c/0x51b [] ? remove_wait_queue+0x22/0x27 [] ? __wake_up+0x32/0x3b [] probes_write+0xd4/0x10a [] ? probes_write+0x0/0x10a [] vfs_write+0x80/0xdf [] sys_write+0x3b/0x5d [] syscall_call+0x7/0xb ---[ end trace 2b962b5dc1fdc07d ]--- Signed-off-by: Masami Hiramatsu Cc: Jim Keniston Cc: Ananth N Mavinakayanahalli Cc: Andi Kleen Cc: Christoph Hellwig Cc: Frank Ch. Eigler Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Ingo Molnar Cc: Jason Baron Cc: K.Prasad Cc: Lai Jiangshan Cc: Li Zefan Cc: Peter Zijlstra Cc: Srikar Dronamraju Cc: Steven Rostedt Cc: Tom Zanussi --- kernel/trace/trace_events.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index ba34920..83cc2c0 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -1010,9 +1010,12 @@ static int __trace_add_event_call(struct ftrace_event_call *call) return -ENOENT; list_add(&call->list, &ftrace_events); - return event_create_dir(call, d_events, &ftrace_event_id_fops, + ret = event_create_dir(call, d_events, &ftrace_event_id_fops, &ftrace_enable_fops, &ftrace_event_filter_fops, &ftrace_event_format_fops); + if (ret < 0) + list_del(&call->list); + return ret; } /* Add an additional event_call dynamically */ -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division e-mail: mhiramat@redhat.com -- 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/