On 04/26/2013 04:32 PM, Robert Jennings wrote:
> With this patch before a migration/hibernation all threads present but
> not online will be brought online. After migration/hibernation those
> threads are taken back offline.
>
> During migration/hibernation all online CPUs must call H_JOIN, this is
> required by the hypervisor. Without this patch, threads that are offline
> (H_CEDE'd) will not be woken to make the H_JOIN call and the OS will be
> deadlocked (all threads either JOIN'd or CEDE'd).
>
This fixes a long standing bug in partition migration.
Acked-by: Nathan Fontenot <nf...@linux.vnet.ibm.com>
> Cc: <sta...@kernel.org>
> Signed-off-by: Robert Jennings <r...@linux.vnet.ibm.com>
> ---
> arch/powerpc/include/asm/rtas.h | 2 +
> arch/powerpc/kernel/rtas.c | 95
> ++++++++++++++++++++++++++++++
> arch/powerpc/platforms/pseries/suspend.c | 22 +++++++
> 3 files changed, 119 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
> index aef00c6..ee38f29 100644
> --- a/arch/powerpc/include/asm/rtas.h
> +++ b/arch/powerpc/include/asm/rtas.h
> @@ -262,6 +262,8 @@ extern void rtas_progress(char *s, unsigned short hex);
> extern void rtas_initialize(void);
> extern int rtas_suspend_cpu(struct rtas_suspend_me_data *data);
> extern int rtas_suspend_last_cpu(struct rtas_suspend_me_data *data);
> +extern int rtas_online_cpus_mask(cpumask_var_t cpus);
> +extern int rtas_offline_cpus_mask(cpumask_var_t cpus);
> extern int rtas_ibm_suspend_me(struct rtas_args *);
>
> struct rtc_time;
> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
> index 1fd6e7b..855ee98 100644
> --- a/arch/powerpc/kernel/rtas.c
> +++ b/arch/powerpc/kernel/rtas.c
> @@ -19,6 +19,7 @@
> #include <linux/init.h>
> #include <linux/capability.h>
> #include <linux/delay.h>
> +#include <linux/cpu.h>
> #include <linux/smp.h>
> #include <linux/completion.h>
> #include <linux/cpumask.h>
> @@ -807,6 +808,77 @@ static void rtas_percpu_suspend_me(void *info)
> __rtas_suspend_cpu((struct rtas_suspend_me_data *)info, 1);
> }
>
> +enum rtas_cpu_state {
> + DOWN,
> + UP,
> +};
> +
> +/* On return cpumask will be altered to indicate CPUs changed */
> +static int rtas_cpu_state_change_mask(enum rtas_cpu_state state,
> + cpumask_var_t cpus)
> +{
> + int cpu;
> + int cpuret = 0;
> + int ret = 0;
> +
> + if (cpumask_empty(cpus))
> + return 0;
> +
> + for_each_cpu(cpu, cpus) {
> + switch (state) {
> + case DOWN:
> + cpuret = cpu_down(cpu);
> + break;
> + case UP:
> + cpuret = cpu_up(cpu);
> + break;
> + }
> + if (cpuret) {
> + pr_debug("%s: cpu_%s for cpu#%d returned %d.\n",
> + __func__,
> + ((state == UP) ? "up" : "down"),
> + cpu, cpuret);
> + if (!ret)
> + ret = cpuret;
> + if (state == UP) {
> + cpumask_shift_right(cpus, cpus, cpu);
> + cpumask_shift_left(cpus, cpus, cpu);
> + break;
> + } else
> + cpumask_clear_cpu(cpu, cpus);
> + }
> + }
> +
> + return ret;
> +}
> +
> +int rtas_online_cpus_mask(cpumask_var_t cpus)
> +{
> + int ret;
> +
> + ret = rtas_cpu_state_change_mask(UP, cpus);
> +
> + if (ret) {
> + cpumask_var_t tmp_mask;
> +
> + if (!alloc_cpumask_var(&tmp_mask, GFP_TEMPORARY))
> + return ret;
> +
> + cpumask_copy(tmp_mask, cpus);
> + rtas_offline_cpus_mask(tmp_mask);
> + free_cpumask_var(tmp_mask);
> + }
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(rtas_online_cpus_mask);
> +
> +int rtas_offline_cpus_mask(cpumask_var_t cpus)
> +{
> + return rtas_cpu_state_change_mask(DOWN, cpus);
> +}
> +EXPORT_SYMBOL(rtas_offline_cpus_mask);
> +
> int rtas_ibm_suspend_me(struct rtas_args *args)
> {
> long state;
> @@ -814,6 +886,8 @@ int rtas_ibm_suspend_me(struct rtas_args *args)
> unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
> struct rtas_suspend_me_data data;
> DECLARE_COMPLETION_ONSTACK(done);
> + cpumask_var_t offline_mask;
> + int cpuret;
>
> if (!rtas_service_present("ibm,suspend-me"))
> return -ENOSYS;
> @@ -837,11 +911,24 @@ int rtas_ibm_suspend_me(struct rtas_args *args)
> return 0;
> }
>
> + if (!alloc_cpumask_var(&offline_mask, GFP_TEMPORARY))
> + return -ENOMEM;
> +
> atomic_set(&data.working, 0);
> atomic_set(&data.done, 0);
> atomic_set(&data.error, 0);
> data.token = rtas_token("ibm,suspend-me");
> data.complete = &done;
> +
> + /* All present CPUs must be online */
> + cpumask_andnot(offline_mask, cpu_present_mask, cpu_online_mask);
> + cpuret = rtas_online_cpus_mask(offline_mask);
> + if (cpuret) {
> + pr_err("%s: Could not bring present CPUs online.\n", __func__);
> + atomic_set(&data.error, cpuret);
> + goto out;
> + }
> +
> stop_topology_update();
>
> /* Call function on all CPUs. One of us will make the
> @@ -857,6 +944,14 @@ int rtas_ibm_suspend_me(struct rtas_args *args)
>
> start_topology_update();
>
> + /* Take down CPUs not online prior to suspend */
> + cpuret = rtas_offline_cpus_mask(offline_mask);
> + if (cpuret)
> + pr_warn("%s: Could not restore CPUs to offline state.\n",
> + __func__);
> +
> +out:
> + free_cpumask_var(offline_mask);
> return atomic_read(&data.error);
> }
> #else /* CONFIG_PPC_PSERIES */
> diff --git a/arch/powerpc/platforms/pseries/suspend.c
> b/arch/powerpc/platforms/pseries/suspend.c
> index 47226e0..5f997e7 100644
> --- a/arch/powerpc/platforms/pseries/suspend.c
> +++ b/arch/powerpc/platforms/pseries/suspend.c
> @@ -16,6 +16,7 @@
> * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> */
>
> +#include <linux/cpu.h>
> #include <linux/delay.h>
> #include <linux/suspend.h>
> #include <linux/stat.h>
> @@ -126,11 +127,15 @@ static ssize_t store_hibernate(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t count)
> {
> + cpumask_var_t offline_mask;
> int rc;
>
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
>
> + if (!alloc_cpumask_var(&offline_mask, GFP_TEMPORARY))
> + return -ENOMEM;
> +
> stream_id = simple_strtoul(buf, NULL, 16);
>
> do {
> @@ -140,15 +145,32 @@ static ssize_t store_hibernate(struct device *dev,
> } while (rc == -EAGAIN);
>
> if (!rc) {
> + /* All present CPUs must be online */
> + cpumask_andnot(offline_mask, cpu_present_mask,
> + cpu_online_mask);
> + rc = rtas_online_cpus_mask(offline_mask);
> + if (rc) {
> + pr_err("%s: Could not bring present CPUs online.\n",
> + __func__);
> + goto out;
> + }
> +
> stop_topology_update();
> rc = pm_suspend(PM_SUSPEND_MEM);
> start_topology_update();
> +
> + /* Take down CPUs not online prior to suspend */
> + if (!rtas_offline_cpus_mask(offline_mask))
> + pr_warn("%s: Could not restore CPUs to offline "
> + "state.\n", __func__);
> }
>
> stream_id = 0;
>
> if (!rc)
> rc = count;
> +out:
> + free_cpumask_var(offline_mask);
> return rc;
> }
>
--
-Nathan
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
