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tracing, x86/irq: Do not trace arch_local_{*,irq_*}() functions
I triggered a triple fault with gcc 4.5.1 because it did not honor the inline annotation to arch_local_save_flags() function and that function was added to the pool of functions traced by the function tracer. When preempt_schedule() called arch_local_save_flags() (called by irqs_disabled()), it was traced, but the first thing the function tracer does is disable preemption. When it enables preemption, the NEED_RESCHED flag will not have been cleared and the preemption check will trigger the call to preempt_schedule() again. Although the dynamic function tracer crashed immediately, the static version of the function tracer (CONFIG_DYNAMIC_FTRACE is not set) actually was able to show where the problem was. swapper-1 3.N.. 103885us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103886us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103886us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103887us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103887us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103888us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103888us : arch_local_save_flags <-preempt_schedule It went on for a while before it triple faulted with a corrupted stack. The arch_local_save_flags and arch_local_irq_* functions should not be traced. Even though they are marked as inline, gcc may still make them a function and enable tracing of them. The simple solution is to just mark them as notrace. I had to add the <linux/types.h> for this file to include the notrace tag. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20110702033852.733414762@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
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1 changed files with 6 additions and 5 deletions
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@ -60,23 +60,24 @@ static inline void native_halt(void)
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#include <asm/paravirt.h>
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#else
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#ifndef __ASSEMBLY__
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#include <linux/types.h>
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static inline unsigned long arch_local_save_flags(void)
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static inline notrace unsigned long arch_local_save_flags(void)
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{
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return native_save_fl();
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}
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static inline void arch_local_irq_restore(unsigned long flags)
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static inline notrace void arch_local_irq_restore(unsigned long flags)
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{
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native_restore_fl(flags);
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}
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static inline void arch_local_irq_disable(void)
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static inline notrace void arch_local_irq_disable(void)
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{
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native_irq_disable();
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}
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static inline void arch_local_irq_enable(void)
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static inline notrace void arch_local_irq_enable(void)
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{
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native_irq_enable();
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}
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@ -102,7 +103,7 @@ static inline void halt(void)
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/*
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* For spinlocks, etc:
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*/
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static inline unsigned long arch_local_irq_save(void)
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static inline notrace unsigned long arch_local_irq_save(void)
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{
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unsigned long flags = arch_local_save_flags();
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arch_local_irq_disable();
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