• Michel Lespinasse's avatar
    x86: Fix trigger_all_cpu_backtrace() implementation · b52e0a7c
    Michel Lespinasse authored
    The following change fixes the x86 implementation of
    trigger_all_cpu_backtrace(), which was previously (accidentally,
    as far as I can tell) disabled to always return false as on
    architectures that do not implement this function.
    
    trigger_all_cpu_backtrace(), as defined in include/linux/nmi.h,
    should call arch_trigger_all_cpu_backtrace() if available, or
    return false if the underlying arch doesn't implement this
    function.
    
    x86 did provide a suitable arch_trigger_all_cpu_backtrace()
    implementation, but it wasn't actually being used because it was
    declared in asm/nmi.h, which linux/nmi.h doesn't include. Also,
    linux/nmi.h couldn't easily be fixed by including asm/nmi.h,
    because that file is not available on all architectures.
    
    I am proposing to fix this by moving the x86 definition of
    arch_trigger_all_cpu_backtrace() to asm/irq.h.
    
    Tested via: echo l > /proc/sysrq-trigger
    
    Before the change, this uses a fallback implementation which
    shows backtraces on active CPUs (using
    smp_call_function_interrupt() )
    
    After the change, this shows NMI backtraces on all CPUs
    Signed-off-by: default avatarMichel Lespinasse <walken@google.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Link: http://lkml.kernel.org/r/1370518875-1346-1-git-send-email-walken@google.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    b52e0a7c
irq.h 1.14 KB