Messages in this thread | | | Date | Sun, 19 Apr 2009 20:45:51 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] tracing/core: Add current context on tracing recursion warning |
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* Frederic Weisbecker <fweisbec@gmail.com> wrote:
> On Sun, Apr 19, 2009 at 04:01:54PM +0200, Ingo Molnar wrote: > > It would be nice to have this ... but there's no need to do that > > atomic thing - just use printk_once() please. (if we race with > > another instance and get two messages that's not a problem) > > > > Ingo > > > Ah, indeed I forgot about printk_once() > I've updated the repo with the following v2 on: > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing tracing/recursion > > --- > >From e894732989e345ea012de146c37d71dd7ed3575d Mon Sep 17 00:00:00 2001 > From: Frederic Weisbecker <fweisbec@gmail.com> > Date: Sun, 19 Apr 2009 16:18:16 +0200 > Subject: [PATCH v2] tracing/core: Add current context on tracing recursion warning
> > In case of tracing recursion detection, we only get the stacktrace. > But the current context may be very useful to debug the issue. > > This patch adds the softirq/hardirq/nmi context with the warning > using lockdep context display to have a familiar output. > > v2: Use printk_once() > > [ Impact: more information in tracing recursion ] > > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> > --- > kernel/trace/ring_buffer.c | 10 ++++++++++ > 1 files changed, 10 insertions(+), 0 deletions(-) > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index b421b0e..e315178 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -1495,6 +1495,16 @@ static int trace_recursive_lock(void) > if (unlikely(current->trace_recursion & (1 << level))) { > /* Disable all tracing before we do anything else */ > tracing_off_permanent(); > + > + printk_once(KERN_WARNING "Tracing recursion: " > + "[HC%u[%lu]:SC%u[%lu]:NMI[%lu]:HE%u:SE%u]\n", > + current->hardirq_context, > + hardirq_count() >> HARDIRQ_SHIFT, > + current->softirq_context, > + softirq_count() >> SOFTIRQ_SHIFT, > + in_nmi(), current->hardirqs_enabled, > + current->softirqs_enabled); > + > WARN_ON_ONCE(1);
Pulled, thanks Frederic!
btw., we might have done it via:
if (WARN_ON_ONCE(1)) { printk(...); }
as well ... but i have not checked how WARN_ON_ONCE() return value behaves after the first warning - does it return true or false?
Ingo
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