Messages in this thread | | | Date | Wed, 16 Sep 2009 10:17:10 -0400 | From | Masami Hiramatsu <> | Subject | Re: [PATCH tracing/kprobes 2/6] ftrace: Fix trace_add_event_call() to initialize list |
| |
Steven Rostedt wrote: > On Mon, 2009-09-14 at 16:49 -0400, Masami Hiramatsu wrote: >> Initialize event_call.list and 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: >> [<c0438424>] warn_slowpath_common+0x65/0x7c >> [<c05371b3>] ? __list_add+0x27/0x5c >> [<c043846f>] warn_slowpath_fmt+0x24/0x27 >> [<c05371b3>] __list_add+0x27/0x5c >> [<c047f050>] list_add+0xa/0xc >> [<c047f8f5>] trace_add_event_call+0x60/0x97 >> [<c0483133>] command_trace_probe+0x42c/0x51b >> [<c044a1b3>] ? remove_wait_queue+0x22/0x27 >> [<c042a9c0>] ? __wake_up+0x32/0x3b >> [<c04832f6>] probes_write+0xd4/0x10a >> [<c0483222>] ? probes_write+0x0/0x10a >> [<c04b27a9>] vfs_write+0x80/0xdf >> [<c04b289c>] sys_write+0x3b/0x5d >> [<c0670d41>] syscall_call+0x7/0xb >> ---[ end trace 2b962b5dc1fdc07d ]--- >> >> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> >> Cc: Jim Keniston <jkenisto@us.ibm.com> >> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> >> Cc: Andi Kleen <ak@linux.intel.com> >> Cc: Christoph Hellwig <hch@infradead.org> >> Cc: Frank Ch. Eigler <fche@redhat.com> >> Cc: Frederic Weisbecker <fweisbec@gmail.com> >> Cc: H. Peter Anvin <hpa@zytor.com> >> Cc: Ingo Molnar <mingo@elte.hu> >> Cc: Jason Baron <jbaron@redhat.com> >> Cc: K.Prasad <prasad@linux.vnet.ibm.com> >> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> >> Cc: Li Zefan <lizf@cn.fujitsu.com> >> Cc: Peter Zijlstra <peterz@infradead.org> >> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> >> Cc: Steven Rostedt <rostedt@goodmis.org> >> Cc: Tom Zanussi <tzanussi@gmail.com> >> --- >> >> kernel/trace/trace_events.c | 6 +++++- >> 1 files changed, 5 insertions(+), 1 deletions(-) >> >> 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
Thank you,
-- Masami Hiramatsu
Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division
e-mail: mhiramat@redhat.com
| |