• Thomas Gleixner's avatar
    tick/powerclamp: Remove tick_nohz_idle abuse · 1ff5b9fb
    Thomas Gleixner authored
    commit a5fd9733 upstream.
    
    commit 4dbd2771 "tick: export nohz tick idle symbols for module
    use" was merged via the thermal tree without an explicit ack from the
    relevant maintainers.
    
    The exports are abused by the intel powerclamp driver which implements
    a fake idle state from a sched FIFO task. This causes all kinds of
    wreckage in the NOHZ core code which rightfully assumes that
    tick_nohz_idle_enter/exit() are only called from the idle task itself.
    
    Recent changes in the NOHZ core lead to a failure of the powerclamp
    driver and now people try to hack completely broken and backwards
    workarounds into the NOHZ core code. This is completely unacceptable
    and just papers over the real problem. There are way more subtle
    issues lurking around the corner.
    
    The real solution is to fix the powerclamp driver by rewriting it with
    a sane concept, but that's beyond the scope of this.
    
    So the only solution for now is to remove the calls into the core NOHZ
    code from the powerclamp trainwreck along with the exports.
    
    Fixes: d6d71ee4 "PM: Introduce Intel PowerClamp Driver"
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
    Cc: Viresh Kumar <viresh.kumar@linaro.org>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Fengguang Wu <fengguang.wu@intel.com>
    Cc: Frederic Weisbecker <frederic@kernel.org>
    Cc: Pan Jacob jun <jacob.jun.pan@intel.com>
    Cc: LKP <lkp@01.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Zhang Rui <rui.zhang@intel.com>
    Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412181110110.17382@nanosSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
    1ff5b9fb
tick-sched.c 29.2 KB