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Date: Thu, 6 Nov 2008 15:34:28 +0100 From: Ingo Molnar <mingo@...e.hu> To: Steven Rostedt <rostedt@...dmis.org> Cc: Zdenek Kabelac <zdenek.kabelac@...il.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Peter Zijlstra <a.p.zijlstra@...llo.nl> Subject: Re: sys_sched_yield keeps locked irq before call of schedule() * Steven Rostedt <rostedt@...dmis.org> wrote: > > On Thu, 6 Nov 2008, Ingo Molnar wrote: > > > > * Zdenek Kabelac <zdenek.kabelac@...il.com> 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)) { > > debug_atomic_inc(&redundant_hardirqs_on); > > return; > > } > > > > you could add a ftrace_printk("redundant hardirq") call right there, > > enable ftrace, and enable stack tracing of each trace entry: > > Quick note. Currently ftrace_printk only shows up if it is set in the > iter_ctrl. > > echo trace_printk > /debug/tracing/iter_ctrl > > I'll send out a patch to have it on by default. ok, agreed - but in that case please make the NOP tracer tracing_enabled=0 by default. (we'll get a lot of ftrace_printk tracepoints by default otherwise) Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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