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From: Ingo Molnar <>
To: Zdenek Kabelac <>
Cc: Linux Kernel Mailing List <>,
	Peter Zijlstra <>,
	Steven Rostedt <>
Subject: Re: sys_sched_yield keeps locked irq before call of schedule()
Date: Thu, 6 Nov 2008 08:57:54 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

* Zdenek Kabelac <> wrote:

> > is this some special warning you added? The stock kernel certainly 
> > does not emit this warning.
> Yes - it's my personal debug checker that tries to watch wether irq 
> & irqsafe are running in pair. So it shows a warning if there is a 
> call of spin_lock_irq and irq is already dissabled.

btw., i have added lockdep instrumentation for this two years ago, 
it's in the upstream kernel:

/proc/lockdep_stats: redundant hardirq ons:                7744
/proc/lockdep_stats: redundant hardirq offs:            1873736
/proc/lockdep_stats: redundant softirq ons:                   0
/proc/lockdep_stats: redundant softirq offs:                  0

you could extend the code to trace it. See 
kernel/lockdep.c:trace_hardirqs_on_caller(). This bit does it:

        if (unlikely(curr->hardirqs_enabled)) {

you could add a ftrace_printk("redundant hardirq") call right there, 
enable ftrace, and enable stack tracing of each trace entry:

 echo stacktrace > /debug/tracing/iter_ctrl

then you should see all the call sites in /debug/tracing/trace.


  parent reply	other threads:[~2008-11-06  7:58 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-05 12:57 Zdenek Kabelac
2008-11-05 13:01 ` Ingo Molnar
2008-11-05 13:09   ` Zdenek Kabelac
2008-11-05 14:05     ` Arnd Bergmann
2008-11-05 14:37       ` Zdenek Kabelac
2008-11-06  7:57     ` Ingo Molnar [this message]
2008-11-06 13:46       ` Steven Rostedt
2008-11-06 14:34         ` Ingo Molnar
2008-11-06 14:46           ` Steven Rostedt

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