Re: [PATCH v07 2/9] hotplug/cpu: Add operation queuing function

[John Allen <jallen@linux.ibm.com>]

On Fri, Jul 13, 2018 at 03:18:01PM -0500, Michael Bringmann wrote:
>migration/dlpar: This patch adds function dlpar_queue_action()
>which will queued up information about a CPU/Memory 'readd'
>operation according to resource type, action code, and DRC index.
>At a subsequent point, the list of operations can be run/played
>in series.  Examples of such oprations include 'readd' of CPU
>and Memory blocks identified as having changed their associativity
>during an LPAR migration event.
>
>Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
>---
>Changes in patch:
>  -- Correct drc_index before adding to pseries_hp_errorlog struct
>  -- Correct text of notice
>  -- Revise queuing model to save up all of the DLPAR actions for
>     later execution.
>  -- Restore list init statement missing from patch
>  -- Move call to apply queued operations into 'mobility.c'
>  -- Compress some code
>  -- Rename some of queueing function APIs
>  -- Revise implementation to push execution of queued operations
>     to a workqueue task.
>  -- Cleanup reference to outdated queuing operation.
>---
> arch/powerpc/include/asm/rtas.h           |    2 +
> arch/powerpc/platforms/pseries/dlpar.c    |   61 +++++++++++++++++++++++++++++
> arch/powerpc/platforms/pseries/mobility.c |    4 ++
> arch/powerpc/platforms/pseries/pseries.h  |    2 +
> 4 files changed, 69 insertions(+)
>
>diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
>index 71e393c..4f601c7 100644
>--- a/arch/powerpc/include/asm/rtas.h
>+++ b/arch/powerpc/include/asm/rtas.h
>@@ -310,12 +310,14 @@ struct pseries_hp_errorlog {
> 		struct { __be32 count, index; } ic;
> 		char	drc_name[1];
> 	} _drc_u;
>+	struct list_head list;
> };
>
> #define PSERIES_HP_ELOG_RESOURCE_CPU	1
> #define PSERIES_HP_ELOG_RESOURCE_MEM	2
> #define PSERIES_HP_ELOG_RESOURCE_SLOT	3
> #define PSERIES_HP_ELOG_RESOURCE_PHB	4
>+#define PSERIES_HP_ELOG_RESOURCE_PMT	5
>
> #define PSERIES_HP_ELOG_ACTION_ADD	1
> #define PSERIES_HP_ELOG_ACTION_REMOVE	2
>diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
>index a0b20c0..7264b8e 100644
>--- a/arch/powerpc/platforms/pseries/dlpar.c
>+++ b/arch/powerpc/platforms/pseries/dlpar.c
>@@ -25,6 +25,7 @@
> #include <asm/prom.h>
> #include <asm/machdep.h>
> #include <linux/uaccess.h>
>+#include <linux/delay.h>
> #include <asm/rtas.h>
>
> static struct workqueue_struct *pseries_hp_wq;
>@@ -329,6 +330,8 @@ int dlpar_release_drc(u32 drc_index)
> 	return 0;
> }
>
>+static int dlpar_pmt(struct pseries_hp_errorlog *work);
>+
> static int handle_dlpar_errorlog(struct pseries_hp_errorlog *hp_elog)
> {
> 	int rc;
>@@ -357,6 +360,9 @@ static int handle_dlpar_errorlog(struct pseries_hp_errorlog *hp_elog)
> 	case PSERIES_HP_ELOG_RESOURCE_CPU:
> 		rc = dlpar_cpu(hp_elog);
> 		break;
>+	case PSERIES_HP_ELOG_RESOURCE_PMT:
>+		rc = dlpar_pmt(hp_elog);
>+		break;
> 	default:
> 		pr_warn_ratelimited("Invalid resource (%d) specified\n",
> 				    hp_elog->resource);
>@@ -407,6 +413,61 @@ void queue_hotplug_event(struct pseries_hp_errorlog *hp_errlog,
> 	}
> }
>
>+LIST_HEAD(dlpar_delayed_list);
>+
>+int dlpar_queue_action(int resource, int action, u32 drc_index)
>+{
>+	struct pseries_hp_errorlog *hp_errlog;
>+
>+	hp_errlog = kmalloc(sizeof(struct pseries_hp_errorlog), GFP_KERNEL);
>+	if (!hp_errlog)
>+		return -ENOMEM;
>+
>+	hp_errlog->resource = resource;
>+	hp_errlog->action = action;
>+	hp_errlog->id_type = PSERIES_HP_ELOG_ID_DRC_INDEX;
>+	hp_errlog->_drc_u.drc_index = cpu_to_be32(drc_index);
>+
>+	list_add_tail(&hp_errlog->list, &dlpar_delayed_list);
>+
>+	return 0;
>+}
>+
>+static int dlpar_pmt(struct pseries_hp_errorlog *work)
>+{
>+	struct list_head *pos, *q;
>+
>+	ssleep(15);

Why do we need to sleep for so long here?

-John

>+
>+	list_for_each_safe(pos, q, &dlpar_delayed_list) {
>+		struct pseries_hp_errorlog *tmp;
>+
>+		tmp = list_entry(pos, struct pseries_hp_errorlog, list);
>+		handle_dlpar_errorlog(tmp);
>+
>+		list_del(pos);
>+		kfree(tmp);
>+
>+		ssleep(10);
>+	}
>+
>+	return 0;
>+}
>+
>+int dlpar_queued_actions_run(void)
>+{
>+	if (!list_empty(&dlpar_delayed_list)) {
>+		struct pseries_hp_errorlog hp_errlog;
>+
>+		hp_errlog.resource = PSERIES_HP_ELOG_RESOURCE_PMT;
>+		hp_errlog.action = 0;
>+		hp_errlog.id_type = 0;
>+
>+		queue_hotplug_event(&hp_errlog, 0, 0);
>+	}
>+	return 0;
>+}
>+
> static int dlpar_parse_resource(char **cmd, struct pseries_hp_errorlog *hp_elog)
> {
> 	char *arg;
>diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
>index f6364d9..d0d1cae 100644
>--- a/arch/powerpc/platforms/pseries/mobility.c
>+++ b/arch/powerpc/platforms/pseries/mobility.c
>@@ -378,6 +378,10 @@ static ssize_t migration_store(struct class *class,
> 		return rc;
>
> 	post_mobility_fixup();
>+
>+	/* Apply any necessary changes identified during fixup */
>+	dlpar_queued_actions_run();
>+
> 	return count;
> }
>
>diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
>index 60db2ee..72ca996 100644
>--- a/arch/powerpc/platforms/pseries/pseries.h
>+++ b/arch/powerpc/platforms/pseries/pseries.h
>@@ -61,6 +61,8 @@ extern struct device_node *dlpar_configure_connector(__be32,
>
> void queue_hotplug_event(struct pseries_hp_errorlog *hp_errlog,
> 			 struct completion *hotplug_done, int *rc);
>+int dlpar_queue_action(int resource, int action, u32 drc_index);
>+int dlpar_queued_actions_run(void);
> #ifdef CONFIG_MEMORY_HOTPLUG
> int dlpar_memory(struct pseries_hp_errorlog *hp_elog);
> #else
>