Commit 120496ac authored by Robert Jennings's avatar Robert Jennings Committed by Benjamin Herrenschmidt
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powerpc: Bring all threads online prior to migration/hibernation 



This patch brings online all threads which are present but not online
prior to migration/hibernation.  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).

Cc: <stable@kernel.org>
Signed-off-by: default avatarRobert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent a94a1472

arch/powerpc/include/asm/rtas.h

+2 −0
Original line number Diff line number Diff line
@@ -264,6 +264,8 @@ 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;

arch/powerpc/kernel/rtas.c

+113 −0
Original line number Diff line number Diff line
@@ -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 +808,95 @@ static void rtas_percpu_suspend_me(void *info) 
	__rtas_suspend_cpu((struct rtas_suspend_me_data *)info, 1);

}



enum rtas_cpu_state {

	DOWN,

	UP,

};



#ifndef CONFIG_SMP

static int rtas_cpu_state_change_mask(enum rtas_cpu_state state,

				cpumask_var_t cpus)

{

	if (!cpumask_empty(cpus)) {

		cpumask_clear(cpus);

		return -EINVAL;

	} else

		return 0;

}

#else

/* On return cpumask will be altered to indicate CPUs changed.

 * CPUs with states changed will be set in the mask,

 * CPUs with status unchanged will be unset in the mask. */

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) {

				/* clear bits for unchanged cpus, return */

				cpumask_shift_right(cpus, cpus, cpu);

				cpumask_shift_left(cpus, cpus, cpu);

				break;

			} else {

				/* clear bit for unchanged cpu, continue */

				cpumask_clear_cpu(cpu, cpus);

			}

		}

	}



	return ret;

}

#endif



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;



		/* Use tmp_mask to preserve cpus mask from first failure */

		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 +904,8 @@ 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 +929,24 @@ 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 +962,14 @@ 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 */

arch/powerpc/platforms/pseries/suspend.c

+22 −0
Original line number Diff line number Diff line
@@ -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;

}

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