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authorSteven Rostedt <srostedt@redhat.com>2011-07-02 05:04:36 +0200
committerIngo Molnar <mingo@elte.hu>2011-07-07 19:22:32 +0200
commite08fbb78f03fe2c4f88824faf6f51ce6af185e11 (patch)
treec15a70f94c4123afd3075a0ed73ea18022f7ad7a /kernel/trace/trace.h
parentMerge branch 'tip/perf/core-2' of git://git.kernel.org/pub/scm/linux/kernel/g... (diff)
downloadlinux-e08fbb78f03fe2c4f88824faf6f51ce6af185e11.tar.xz
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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>
Diffstat (limited to 'kernel/trace/trace.h')
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