IB: Allow userspace to set node description

Expose a writable "node_desc" sysfs attribute for InfiniBand devices.
This allows userspace to update the node description with information
such as the node's hostname, so that IB network management software
can tie its view to the real world.

Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

2 files changed, 33 insertions, 2 deletions

diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c
index 5982d687a000..49601bb8475b 100644
--- a/drivers/infiniband/core/sysfs.c
+++ b/drivers/infiniband/core/sysfs.c
@@ -628,14 +628,42 @@ static ssize_t show_node_guid(struct class_device *cdev, char *buf)
                        be16_to_cpu(((__be16 *) &dev->node_guid)[3]));
 }
 
+static ssize_t show_node_desc(struct class_device *cdev, char *buf)
+{
+        struct ib_device *dev = container_of(cdev, struct ib_device, class_dev);
+
+        return sprintf(buf, "%.64s\n", dev->node_desc);
+}
+
+static ssize_t set_node_desc(struct class_device *cdev, const char *buf,
+                              size_t count)
+{
+        struct ib_device *dev = container_of(cdev, struct ib_device, class_dev);
+        struct ib_device_modify desc = {};
+        int ret;
+
+        if (!dev->modify_device)
+                return -EIO;
+
+        memcpy(desc.node_desc, buf, min_t(int, count, 64));
+        ret = ib_modify_device(dev, IB_DEVICE_MODIFY_NODE_DESC, &desc);
+        if (ret)
+                return ret;
+
+        return count;
+}
+
 static CLASS_DEVICE_ATTR(node_type, S_IRUGO, show_node_type, NULL);
 static CLASS_DEVICE_ATTR(sys_image_guid, S_IRUGO, show_sys_image_guid, NULL);
 static CLASS_DEVICE_ATTR(node_guid, S_IRUGO, show_node_guid, NULL);
+static CLASS_DEVICE_ATTR(node_desc, S_IRUGO | S_IWUSR, show_node_desc,
+                         set_node_desc);
 
 static struct class_device_attribute *ib_class_attributes[] = {
         &class_device_attr_node_type,
         &class_device_attr_sys_image_guid,
-        &class_device_attr_node_guid
+        &class_device_attr_node_guid,
+        &class_device_attr_node_desc
 };
 
 static struct class ib_class = {
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 38fa6c082eae..1d31c8cd5ce0 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -222,11 +222,13 @@ struct ib_port_attr {
 };
 
 enum ib_device_modify_flags {
-        IB_DEVICE_MODIFY_SYS_IMAGE_GUID = 1
+        IB_DEVICE_MODIFY_SYS_IMAGE_GUID = 1 << 0,
+        IB_DEVICE_MODIFY_NODE_DESC      = 1 << 1
 };
 
 struct ib_device_modify {
         u64     sys_image_guid;
+        char    node_desc[64];
 };
 
 enum ib_port_modify_flags {
@@ -951,6 +953,7 @@ struct ib_device {
         u64                          uverbs_cmd_mask;
         int                          uverbs_abi_ver;
 
+        char                         node_desc[64];
         __be64                       node_guid;
         u8                           node_type;
         u8                           phys_port_cnt;