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
