On 6 March 2014 09:23, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > On Tuesday, March 04, 2014 12:42:15 PM Aaron Plattner wrote: >> If a module calls cpufreq_get while cpufreq is initializing, it's possible for >> it to be called after cpufreq_driver is set but before cpufreq_cpu_data is >> written during subsys_interface_register. This happens because cpufreq_get >> doesn't take the cpufreq_driver_lock around its use of cpufreq_cpu_data. > > Is this a theoretical race, or can you actually reproduce it? If so, on what > system/driver? Or are there any bug reports related to this you can point me > to? > >> Fix this by using cpufreq_cpu_get(cpu) to look up the policy rather than reading >> it out of cpufreq_cpu_data directly. cpufreq_cpu_get takes the appropriate >> locks to prevent this race from happening. >> >> Since it's possible for policy to be NULL if the caller passes in an invalid CPU >> number or calls the function before cpufreq is initialized, delete the >> BUG_ON(!policy) and simply return 0. Don't try to return -ENOENT because that's >> negative and the function returns an unsigned integer. >> >> Signed-off-by: Aaron Plattner <aplattner@xxxxxxxxxx> > > Viresh, have you seen this? Sorry for being late. Though I see you have already applied this one, I will still add this for records :) Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
