Messages in this thread | | | Date | Thu, 15 Apr 2010 20:52:42 -0700 | Subject | Re: [PATCH 3/3] Stop tracing on a schedule bug | From | Chase Douglas <> |
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On Thu, Apr 15, 2010 at 4:50 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > On Thu, 15 Apr 2010, Chase Douglas wrote: >> On Thu, Apr 15, 2010 at 4:01 PM, Thomas Gleixner <tglx@linutronix.de> wrote: >> > On Thu, 15 Apr 2010, Chase Douglas wrote: >> >> On Thu, Apr 15, 2010 at 2:03 PM, Frederic Weisbecker <fweisbec@gmail.com> wrote: >> >> > On Wed, Apr 14, 2010 at 12:20:16PM -0400, Chase Douglas wrote: >> >> >> This change adds a tracing_off_event() call to stop tracing on schedule >> >> >> bugs unless tracing_off=none was specified on the commandline. >> >> >> >> >> >> Signed-off-by: Chase Douglas <chase.douglas@canonical.com> >> >> >> --- >> >> >> kernel/sched.c | 2 ++ >> >> >> 1 files changed, 2 insertions(+), 0 deletions(-) >> >> >> >> >> >> diff --git a/kernel/sched.c b/kernel/sched.c >> >> >> index 6af210a..439f036 100644 >> >> >> --- a/kernel/sched.c >> >> >> +++ b/kernel/sched.c >> >> >> @@ -3590,6 +3590,8 @@ static noinline void __schedule_bug(struct task_struct *prev) >> >> >> { >> >> >> struct pt_regs *regs = get_irq_regs(); >> >> >> >> >> >> + tracing_off_event(TRACE_EVENT_BUG); >> >> >> + >> >> >> printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", >> >> >> prev->comm, prev->pid, preempt_count()); >> >> > >> >> > >> >> > >> >> > I would rather call that a TRACE_EVENT_WARN as this is what happens: we >> >> > warn but we continue. >> >> >> >> I tend to think of the TRACE_EVENT_* as an indication of severity and >> >> whether we want to stop the trace by default. From a distro >> >> standpoint, the likelihood that we want to continue tracing after a >> >> __schedule_bug is pretty low. It's easiest if we don't have to tell >> > >> > Well, scheduling while atomic is a BUG, but one of the category which >> > allows the kernel to continue. So in fact it's treated like a WARN_ON. >> > So the tracing_off_event() qualifier should be *_WARN. >> > >> > That's independent of the question whether you want to stop tracing in >> > that very case. Though I agree that the tracer should stop here. >> >> We seem to be agreeing on the functionality. The disagreement seems to >> be in the macro name/functionality mapping. However, the name of the >> function itself is *_bug. I don't see how things are clearer or more >> useful by inserting a *_WARN level macro in a *_bug named function. > > Care to read what I wrote ? Again:
I misunderstood what you wrote. I thought you were agreeing that the tracing should stop by default in __schedule_bug. I now realize you meant that you agree it should be possible to stop it, but it should not be the default behavior. Sorry for the confusion.
I will change the event to be a *_WARN type.
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