• Viresh Kumar's avatar
    cpufreq: Don't use cpu removed during cpufreq_driver_unregister · 6954ca9c
    Viresh Kumar authored
    This is how the core works:
    cpufreq_driver_unregister()
     - subsys_interface_unregister()
       - for_each_cpu() call cpufreq_remove_dev(), i.e. 0,1,2,3,4 when we
         unregister.
    
    cpufreq_remove_dev():
     - Remove policy node
     - Call cpufreq_add_dev() for next cpu, sharing mask with removed cpu.
       i.e. When cpu 0 is removed, we call it for cpu 1. And when called for cpu 2,
       we call it for cpu 3.
       - cpufreq_add_dev() would call cpufreq_driver->init()
       - init would return mask as AND of 2, 3 and 4 for cluster A7.
       - cpufreq core would do online_cpu && policy->cpus
         Here is the BUG(). Because cpu hasn't died but we have just unregistered
         the cpufreq driver, online cpu would still have cpu 2 in it. And so thing
         go bad again.
    
    Solution: Keep cpumask of cpus that are registered with cpufreq core and clear
    	  cpus when we get a call from subsys_interface_unregister() via
    	  cpufreq_remove_dev().
    Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    6954ca9c
cpufreq.c 50.1 KB