Hi Nathan,
Just a couple of nits ...
Nathan Lynch <nath...@linux.ibm.com> writes:
> The partition suspend sequence as specified in the platform
> architecture requires that all active processor threads call
> H_JOIN, which:
...
> diff --git a/arch/powerpc/platforms/pseries/mobility.c
> b/arch/powerpc/platforms/pseries/mobility.c
> index 1b8ae221b98a..44ca7d4e143d 100644
> --- a/arch/powerpc/platforms/pseries/mobility.c
> +++ b/arch/powerpc/platforms/pseries/mobility.c
> @@ -412,6 +414,128 @@ static int wait_for_vasi_session_suspending(u64 handle)
...
> +
> +static int do_join(void *arg)
> +{
> + atomic_t *counter = arg;
> + long hvrc;
> + int ret;
> +
> + /* Must ensure MSR.EE off for H_JOIN. */
> + hard_irq_disable();
Didn't stop_machine() already do that for us?
In the state machine in multi_cpu_stop().
> + hvrc = plpar_hcall_norets(H_JOIN);
> +
> + switch (hvrc) {
> + case H_CONTINUE:
> + /*
> + * All other CPUs are offline or in H_JOIN. This CPU
> + * attempts the suspend.
> + */
> + ret = do_suspend();
> + break;
> + case H_SUCCESS:
> + /*
> + * The suspend is complete and this cpu has received a
> + * prod.
> + */
> + ret = 0;
> + break;
> + case H_BAD_MODE:
> + case H_HARDWARE:
> + default:
> + ret = -EIO;
> + pr_err_ratelimited("H_JOIN error %ld on CPU %i\n",
> + hvrc, smp_processor_id());
> + break;
> + }
> +
> + if (atomic_inc_return(counter) == 1) {
> + pr_info("CPU %u waking all threads\n", smp_processor_id());
> + prod_others();
> + }
Do we even need the counter? IIUC only one CPU receives H_CONTINUE. So
couldn't we just have that CPU do the prodding of others?
> + /*
> + * Execution may have been suspended for several seconds, so
> + * reset the watchdog.
> + */
> + touch_nmi_watchdog();
> + return ret;
> +}
> +
> +static int pseries_migrate_partition(u64 handle)
> +{
> + atomic_t counter = ATOMIC_INIT(0);
> + int ret;
> +
> + ret = wait_for_vasi_session_suspending(handle);
> + if (ret)
> + goto out;
Direct return would be clearer IMHO.
> +
> + ret = stop_machine(do_join, &counter, cpu_online_mask);
> + if (ret == 0)
> + post_mobility_fixup();
> +out:
> + return ret;
> +}
> +
cheers
