• Steven Rostedt's avatar
    powerpc/ftrace: Do not trace restore_interrupts() · 2d773aa4
    Steven Rostedt authored
    As I was adding code that affects all archs, I started testing function
    tracer against PPC64 and found that it currently locks up with 3.4
    kernel. I figured it was due to tracing a function that shouldn't be, so
    I went through the following process to bisect to find the culprit:
     cat /debug/tracing/available_filter_functions > t
     num=`wc -l t`
     sed -ne "1,${num}p" t > t1
     let num=num+1
     sed -ne "${num},$p" t > t2
     cat t1 > /debug/tracing/set_ftrace_filter
     echo function /debug/tracing/current_tracer
     <failed? bisect t1, if not bisect t2>
    It finally came down to this function: restore_interrupts()
    I'm not sure why this locks up the system. It just seems to prevent
    scheduling from occurring. Interrupts seem to still work, as I can ping
    the box. But all user processes freeze.
    When restore_interrupts() is not traced, function tracing works fine.
    Cc: stable@kernel.org
    Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
irq.c 15.6 KB