• Frederic Weisbecker's avatar
    tracing/function-graph-tracer: prevent hangs during self-tests · cf586b61
    Frederic Weisbecker authored
    Impact: detect tracing related hangs
    Sometimes, with some configs, the function graph tracer can make
    the timer interrupt too much slow, hanging the kernel in an endless
    loop of timer interrupts servicing.
    As suggested by Ingo, this patch brings a watchdog which stops the
    selftest after a defined number of functions traced, definitely
    disabling this tracer.
    For those who want to debug the cause of the function graph trace
    hang, you can pass the ftrace_dump_on_oops kernel parameter to dump
    the traces after this hang detection.
    Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    LKML-Reference: <1237694675-23509-1-git-send-email-fweisbec@gmail.com>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>