• Preeti U Murthy's avatar
    cpuidle: Handle clockevents_notify(BROADCAST_ENTER) failure · ba8f20c2
    Preeti U Murthy authored
    
    
    Some archs set the CPUIDLE_FLAG_TIMER_STOP flag for idle states in which the
    local timers stop. The cpuidle_idle_call() currently handles such idle states
    by calling into the broadcast framework so as to wakeup CPUs at their next
    wakeup event. With the hrtimer mode of broadcast, the BROADCAST_ENTER call
    into the broadcast frameowork can fail for archs that do not have an external
    clock device to handle wakeups and the CPU in question has thus to be made
    the stand by CPU. This patch handles such cases by failing the call into
    cpuidle so that the arch can take some default action. The arch will certainly
    not enter a similar idle state because a failed cpuidle call will also implicitly
    indicate that the broadcast framework has not registered this CPU to be woken up.
    Hence we are safe if we fail the cpuidle call.
    
    In the process move the functions that trace idle statistics just before and
    after the entry and exit into idle states respectively. In other
    scenarios where the call to cpuidle fails, we end up not tracing idle
    entry and exit since a decision on an idle state could not be taken. Similarly
    when the call to broadcast framework fails, we skip tracing idle statistics
    because we are in no further position to take a decision on an alternative
    idle state to enter into.
    
    Signed-off-by: default avatarPreeti U Murthy <preeti@linux.vnet.ibm.com>
    Cc: deepthi@linux.vnet.ibm.com
    Cc: paulmck@linux.vnet.ibm.com
    Cc: fweisbec@gmail.com
    Cc: paulus@samba.org
    Cc: srivatsa.bhat@linux.vnet.ibm.com
    Cc: svaidy@linux.vnet.ibm.com
    Cc: peterz@infradead.org
    Cc: benh@kernel.crashing.org
    Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    Cc: linuxppc-dev@lists.ozlabs.org
    Link: http://lkml.kernel.org/r/20140207080652.17187.66344.stgit@preeti.in.ibm.com
    
    
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    ba8f20c2