Messages in this thread | | | Date | Sun, 23 Nov 2008 11:35:07 -0500 (EST) | From | Steven Rostedt <> | Subject | Re: Mmiotrace regression in 2.6.28-rc6 |
| |
On Sun, 23 Nov 2008, Pekka Paalanen wrote:
> Hi Steve, > > now that the NULL deref bug in ring buffer resize is gone, I found > another regression. > > It seems I am not getting any "buffer overflow" messages anymore. > > Oh bummer, looks like I completely missed this one: > (hope it's not in any .27 kernel) > > > commit 3928a8a2d98081d1bc3c0a84a2d70e29b90ecf1c > Author: Steven Rostedt <rostedt@goodmis.org> > Date: Mon Sep 29 23:02:41 2008 -0400 > > ftrace: make work with new ring buffer > > This patch ports ftrace over to the new ring buffer. > > Signed-off-by: Steven Rostedt <srostedt@redhat.com> > Signed-off-by: Ingo Molnar <mingo@elte.hu> > > <...> > diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c > index a108c32..bdbf09d 100644 > --- a/kernel/trace/trace_mmiotrace.c > +++ b/kernel/trace/trace_mmiotrace.c > <...> > @@ -130,10 +130,14 @@ static unsigned long count_overruns(struct trace_iterator *iter) > { > int cpu; > unsigned long cnt = 0; > +/* FIXME: */ > +#if 0 > for_each_online_cpu(cpu) { > cnt += iter->overrun[cpu]; > iter->overrun[cpu] = 0; > } > +#endif
Hi Pekka,
Use ring_buffer_overruns(iter->tr->buffer). See print_trace_hader in kernel/trace/trace.c for more info.
-- Steve
> + (void)cpu; > return cnt; > } > > Steve, how am I going to fix this? > I think it's quite crucial to know when the dump is incomplete. > > > There's also another issue, but I am not sure how to reproduce it. > The symptom is, that > echo whatever > /debug/tracing/trace_marker > gets stuck in a loop, bash eats 100% CPU: 10% user, 90% system. > I got that twice today, like this: after a fresh boot echoing 64, 200, > 70 to trace_entries, switching between nop and mmiotrace tracers, > echoing 0 or 1 to tracing_enabled, and running the testmmiotrace > module. At some point the user marker got stuck. > > But then I tried to do that a third time by repeating some usage > patterns I thought might trigger it, but it didn't happen. > > On the positive side, the basic test using testmmiotrace.ko > with the basic setup produces the correct output. > > > Thanks. > > -- > Pekka Paalanen > http://www.iki.fi/pq/ > >
| |