NVMe: CPU hot plug notification

Registers with hot cpu notification to rebalance, and potentially allocate
additional, io queues.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 48d7bd55207a..ce5a4f1a3950 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -2002,6 +2002,19 @@ static size_t db_bar_size(struct nvme_dev *dev, unsigned nr_io_queues)
         return 4096 + ((nr_io_queues + 1) * 8 * dev->db_stride);
 }
 
+static int nvme_cpu_notify(struct notifier_block *self,
+                                unsigned long action, void *hcpu)
+{
+        struct nvme_dev *dev = container_of(self, struct nvme_dev, nb);
+        switch (action) {
+        case CPU_ONLINE:
+        case CPU_DEAD:
+                nvme_assign_io_queues(dev);
+                break;
+        }
+        return NOTIFY_OK;
+}
+
 static int nvme_setup_io_queues(struct nvme_dev *dev)
 {
         struct nvme_queue *adminq = raw_nvmeq(dev, 0);
@@ -2080,6 +2093,11 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
         nvme_free_queues(dev, nr_io_queues + 1);
         nvme_assign_io_queues(dev);
 
+        dev->nb.notifier_call = &nvme_cpu_notify;
+        result = register_hotcpu_notifier(&dev->nb);
+        if (result)
+                goto free_queues;
+
         return 0;
 
  free_queues:
@@ -2357,6 +2375,7 @@ static void nvme_dev_shutdown(struct nvme_dev *dev)
         int i;
 
         dev->initialized = 0;
+        unregister_hotcpu_notifier(&dev->nb);
 
         spin_lock(&dev_list_lock);
         list_del_init(&dev->node);