virtio-scsi: reset virtqueue affinity when doing cpu hotplug

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

Cc: linux-scsi@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Reviewed-by: Asias He <asias@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 29 insertions, 0 deletions

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 8dcdef0783db..2168258fb2c3 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -110,6 +110,9 @@ struct virtio_scsi {
         /* If 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[];
@@ -762,6 +765,23 @@ 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)
+{
+        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)
 {
@@ -884,6 +904,13 @@ 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");
+                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;
@@ -921,6 +948,8 @@ static void virtscsi_remove(struct virtio_device *vdev)
 
         scsi_remove_host(shost);
 
+        unregister_hotcpu_notifier(&vscsi->nb);
+
         virtscsi_remove_vqs(vdev);
         scsi_host_put(shost);
 }