Re: [PATCH -rt] wrong usage of smp_processor_id()

[Steven Rostedt <srostedt@redhat.com>]

Daniel Walker wrote:

>>> Index: linux-2.6.21/kernel/latency_trace.c
>>> ===================================================================
>>> --- linux-2.6.21.orig/kernel/latency_trace.c
>>> +++ linux-2.6.21/kernel/latency_trace.c
>>> @@ -105,7 +105,7 @@ static inline int DEBUG_WARN_ON(int cond
>>>  #ifdef CONFIG_CRITICAL_IRQSOFF_TIMING
>>>  # ifdef CONFIG_CRITICAL_PREEMPT_TIMING
>>>     static DEFINE_PER_CPU(int, trace_cpu_idle);
>>> -#  define irqs_off_preempt_count() (!__get_cpu_var(trace_cpu_idle) && preempt_count())
>>> +#  define irqs_off_preempt_count() (preempt_count() && !__get_cpu_var(trace_cpu_idle))
>>>  # else
>>>  #  define irqs_off_preempt_count() 0
>>>  # endif


> Isn't it a generic problem? It doesn't look specific to your change
> unless you made some changes to entry.S .
> 

See: http://lkml.org/lkml/2007/4/23/183

Specifically:


  #ifdef CONFIG_CRITICAL_IRQSOFF_TIMING
  # ifdef CONFIG_CRITICAL_PREEMPT_TIMING
-#  define irqs_off_preempt_count() preempt_count()
+   static DEFINE_PER_CPU(int, trace_cpu_idle);
+#  define irqs_off_preempt_count() (!__get_cpu_var(trace_cpu_idle) && 
preempt_count())
  # else
  #  define irqs_off_preempt_count() 0
  # endif
@@ -2153,6 +2154,20 @@ void notrace unmask_preempt_count(unsign
  }
  EXPORT_SYMBOL(unmask_preempt_count);


-- Steve