On Sat, 1 Oct 2016, Srinivas Pandruvada wrote: > +static int sched_itmt_update_handler(struct ctl_table *table, int write, > + void __user *buffer, size_t *lenp, loff_t *ppos) > +{ > + int ret; > + unsigned int old_sysctl; > + > + mutex_lock(&itmt_update_mutex); > + > + if (!sched_itmt_capable) { > + mutex_unlock(&itmt_update_mutex); > + return 0; This should return a proper error code. > void sched_set_itmt_support(bool itmt_supported) > { > mutex_lock(&itmt_update_mutex); > > - if (itmt_supported != sched_itmt_capable) > - sched_itmt_capable = itmt_supported; > + if (itmt_supported == sched_itmt_capable) { > + mutex_unlock(&itmt_update_mutex); > + return; > + } > + sched_itmt_capable = itmt_supported; > + > + if (itmt_supported) { > + itmt_sysctl_header = > + register_sysctl_table(itmt_root_table); > + if (!itmt_sysctl_header) { > + mutex_unlock(&itmt_update_mutex); > + return; So you now have a state of capable which cannot be enabled. Whats the point? > + } > + /* > + * ITMT capability automatically enables ITMT > + * scheduling for small systems (single node). > + */ > + if (topology_num_packages() == 1) > + sysctl_sched_itmt_enabled = 1; > + } else { > + if (itmt_sysctl_header) > + unregister_sysctl_table(itmt_sysctl_header); > + } > + > + if (sysctl_sched_itmt_enabled) { > + /* disable sched_itmt if we are no longer ITMT capable */ > + if (!itmt_supported) How do you get here if itmt is not supported? > + sysctl_sched_itmt_enabled = 0; > + x86_topology_update = true; > + rebuild_sched_domains(); > + } > > mutex_unlock(&itmt_update_mutex); Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html