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Commit 8904f5a5 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Thomas Gleixner
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virtio scsi: Convert to hotplug state machine 



Install the callbacks via the state machine. It uses the multi instance
infrastructure of the hotplug code to handle each interface.

virtscsi_set_affinity() is removed from virtscsi_init() because
virtscsi_cpu_notif_add() (the function which registers the instance) is invoked
right after it and the cpuhp_state_add_instance() functions invokes the startup
callback on all online CPUs.

The same thing can not be applied virtscsi_cpu_notif_remove() because
virtscsi_remove_vqs() invokes virtscsi_set_affinity() with affinity = false as
argument but the old CPU_DEAD state invoked the function with affinity = true
(which does not match the DEAD callback).

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: linux-scsi@vger.kernel.org
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: virtualization@lists.linux-foundation.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-11-bigeasy@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent a4e0591e

drivers/scsi/virtio_scsi.c

+49 −27
Original line number Diff line number Diff line
@@ -107,8 +107,8 @@ struct virtio_scsi { 
	/* If the affinity hint is set for virtqueues */

	bool affinity_hint_set;



	/* CPU hotplug notifier */

	struct notifier_block nb;

	struct hlist_node node;

	struct hlist_node node_dead;



	/* Protected by event_vq lock */

	bool stop_events;
@@ -118,6 +118,7 @@ struct virtio_scsi { 
	struct virtio_scsi_vq req_vqs[];

};



static enum cpuhp_state virtioscsi_online;

static struct kmem_cache *virtscsi_cmd_cache;

static mempool_t *virtscsi_cmd_pool;
@@ -852,21 +853,33 @@ static void virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity) 
	put_online_cpus();

}



static int virtscsi_cpu_callback(struct notifier_block *nfb,

				 unsigned long action, void *hcpu)

static int virtscsi_cpu_online(unsigned int cpu, struct hlist_node *node)

{

	struct virtio_scsi *vscsi = container_of(nfb, struct virtio_scsi, nb);

	switch(action) {

	case CPU_ONLINE:

	case CPU_ONLINE_FROZEN:

	case CPU_DEAD:

	case CPU_DEAD_FROZEN:

	struct virtio_scsi *vscsi = hlist_entry_safe(node, struct virtio_scsi,

						     node);

	__virtscsi_set_affinity(vscsi, true);

		break;

	default:

		break;

	return 0;

}

	return NOTIFY_OK;



static int virtscsi_cpu_notif_add(struct virtio_scsi *vi)

{

	int ret;



	ret = cpuhp_state_add_instance(virtioscsi_online, &vi->node);

	if (ret)

		return ret;



	ret = cpuhp_state_add_instance(CPUHP_VIRT_SCSI_DEAD, &vi->node_dead);

	if (ret)

		cpuhp_state_remove_instance(virtioscsi_online, &vi->node);

	return ret;

}



static void virtscsi_cpu_notif_remove(struct virtio_scsi *vi)

{

	cpuhp_state_remove_instance_nocalls(virtioscsi_online, &vi->node);

	cpuhp_state_remove_instance_nocalls(CPUHP_VIRT_SCSI_DEAD,

					    &vi->node_dead);

}



static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
@@ -929,8 +942,6 @@ static int virtscsi_init(struct virtio_device *vdev, 
		virtscsi_init_vq(&vscsi->req_vqs[i - VIRTIO_SCSI_VQ_BASE],

				 vqs[i]);



	virtscsi_set_affinity(vscsi, true);



	virtscsi_config_set(vdev, cdb_size, VIRTIO_SCSI_CDB_SIZE);

	virtscsi_config_set(vdev, sense_size, VIRTIO_SCSI_SENSE_SIZE);
@@ -987,12 +998,9 @@ static int virtscsi_probe(struct virtio_device *vdev) 
	if (err)

		goto virtscsi_init_failed;



	vscsi->nb.notifier_call = &virtscsi_cpu_callback;

	err = register_hotcpu_notifier(&vscsi->nb);

	if (err) {

		pr_err("registering cpu notifier failed\n");

	err = virtscsi_cpu_notif_add(vscsi);

	if (err)

		goto scsi_add_host_failed;

	}



	cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1;

	shost->cmd_per_lun = min_t(u32, cmd_per_lun, shost->can_queue);
@@ -1049,7 +1057,7 @@ static void virtscsi_remove(struct virtio_device *vdev) 


	scsi_remove_host(shost);



	unregister_hotcpu_notifier(&vscsi->nb);

	virtscsi_cpu_notif_remove(vscsi);



	virtscsi_remove_vqs(vdev);

	scsi_host_put(shost);
@@ -1061,7 +1069,7 @@ static int virtscsi_freeze(struct virtio_device *vdev) 
	struct Scsi_Host *sh = virtio_scsi_host(vdev);

	struct virtio_scsi *vscsi = shost_priv(sh);



	unregister_hotcpu_notifier(&vscsi->nb);

	virtscsi_cpu_notif_remove(vscsi);

	virtscsi_remove_vqs(vdev);

	return 0;

}
@@ -1076,12 +1084,11 @@ static int virtscsi_restore(struct virtio_device *vdev) 
	if (err)

		return err;



	err = register_hotcpu_notifier(&vscsi->nb);

	err = virtscsi_cpu_notif_add(vscsi);

	if (err) {

		vdev->config->del_vqs(vdev);

		return err;

	}



	virtio_device_ready(vdev);



	if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
@@ -1136,6 +1143,16 @@ static int __init init(void) 
		pr_err("mempool_create() for virtscsi_cmd_pool failed\n");

		goto error;

	}

	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,

				      "scsi/virtio:online",

				      virtscsi_cpu_online, NULL);

	if (ret < 0)

		goto error;

	virtioscsi_online = ret;

	ret = cpuhp_setup_state_multi(CPUHP_VIRT_SCSI_DEAD, "scsi/virtio:dead",

				      NULL, virtscsi_cpu_online);

	if (ret)

		goto error;

	ret = register_virtio_driver(&virtio_scsi_driver);

	if (ret < 0)

		goto error;
@@ -1151,12 +1168,17 @@ static int __init init(void) 
		kmem_cache_destroy(virtscsi_cmd_cache);

		virtscsi_cmd_cache = NULL;

	}

	if (virtioscsi_online)

		cpuhp_remove_multi_state(virtioscsi_online);

	cpuhp_remove_multi_state(CPUHP_VIRT_SCSI_DEAD);

	return ret;

}



static void __exit fini(void)

{

	unregister_virtio_driver(&virtio_scsi_driver);

	cpuhp_remove_multi_state(virtioscsi_online);

	cpuhp_remove_multi_state(CPUHP_VIRT_SCSI_DEAD);

	mempool_destroy(virtscsi_cmd_pool);

	kmem_cache_destroy(virtscsi_cmd_cache);

}

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ enum cpuhp_state { 
	CPUHP_ARM_OMAP_WAKE_DEAD,

	CPUHP_IRQ_POLL_DEAD,

	CPUHP_BLOCK_SOFTIRQ_DEAD,

	CPUHP_VIRT_SCSI_DEAD,

	CPUHP_WORKQUEUE_PREP,

	CPUHP_POWER_NUMA_PREPARE,

	CPUHP_HRTIMERS_PREPARE,