[PATCH 2/2] virtio-scsi: reset virtqueue affinity when doing cpu hotplug

[Wanlong Gao]

Add hot cpu notifier to reset the request virtqueue affinity
when doing cpu hotplug.

Signed-off-by: Wanlong Gao <gaowanl...@cn.fujitsu.com>
---
 drivers/scsi/virtio_scsi.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 16b0ef2..a3b5f12 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -20,6 +20,7 @@
 #include <linux/virtio_ids.h>
 #include <linux/virtio_config.h>
 #include <linux/virtio_scsi.h>
+#include <linux/cpu.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_cmnd.h>
@@ -109,6 +110,9 @@ struct virtio_scsi {
        /* Does the affinity hint is set for virtqueues? */
        bool affinity_hint_set;
 
+       /* CPU hotplug notifier */
+       struct notifier_block nb;
+
        struct virtio_scsi_vq ctrl_vq;
        struct virtio_scsi_vq event_vq;
        struct virtio_scsi_vq req_vqs[];
@@ -738,6 +742,23 @@ static void virtscsi_set_affinity(struct virtio_scsi 
*vscsi, bool affinity)
        }
 }
 
+static int virtscsi_cpu_callback(struct notifier_block *nfb,
+                                unsigned long action, void *hcpu)
+{
+       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:
+               virtscsi_set_affinity(vscsi, true);
+               break;
+       default:
+               break;
+       }
+       return NOTIFY_OK;
+}
+
 static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
                             struct virtqueue *vq)
 {
@@ -888,6 +909,13 @@ static int __devinit 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("virtio_scsi: registering cpu notifier failed\n");
+               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);
        shost->max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0xFFFF;
@@ -925,6 +953,8 @@ static void __devexit virtscsi_remove(struct virtio_device 
*vdev)
 
        scsi_remove_host(shost);
 
+       unregister_hotcpu_notifier(&vscsi->nb);
+
        virtscsi_remove_vqs(vdev);
        scsi_host_put(shost);
 }
-- 
1.8.1
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