• Rafael J. Wysocki's avatar
    cpufreq: Drop the 'initialized' field from struct cpufreq_governor · 9a15fb2c
    Rafael J. Wysocki authored
    The 'initialized' field in struct cpufreq_governor is only used by
    the conservative governor (as a usage counter) and the way that
    happens is far from straightforward and arguably incorrect.
    Namely, the value of 'initialized' is checked by
    cpufreq_dbs_governor_init() and cpufreq_dbs_governor_exit() and
    the results of those checks are passed (as the second argument) to
    the ->init() and ->exit() callbacks in struct dbs_governor.  Those
    callbacks are only implemented by the ondemand and conservative
    governors and ondemand doesn't use their second argument at all.
    In turn, the conservative governor uses it to decide whether or not
    to either register or unregister a transition notifier.
    That whole mechanism is not only unnecessarily convoluted, but also
    racy, because the 'initialized' field of struct cpufreq_governor is
    updated in cpufreq_init_governor() and cpufreq_exit_governor() under
    policy->rwsem which doesn't help if one of these functions is run
    twice in parallel for different policies (which isn't impossible in
    principle), for example.
    Instead of it, add a proper usage counter to the conservative
    governor and update it from cs_init() and cs_exit() which is
    guaranteed to be non-racy, as those functions are only called
    under gov_dbs_data_mutex which is global.
    With that in place, drop the 'initialized' field from struct
    cpufreq_governor as it is not used any more.
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>