devlink: Add callback to query for snapshot id before snapshot create

To restrict the driver with the snapshot ID selection a new callback
is introduced for the driver to get the snapshot ID before creating
a new snapshot. This will also allow giving the same ID for multiple
snapshots taken of different regions on the same time.
Signed-off-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/devlink.h

@@ -29,6 +29,7 @@ struct devlink {
 	struct list_head resource_list;
 	struct list_head param_list;
 	struct list_head region_list;
+	u32 snapshot_id;
 	struct devlink_dpipe_headers *dpipe_headers;
 	const struct devlink_ops *ops;
 	struct device *dev;
@@ -551,6 +552,7 @@ struct devlink_region *devlink_region_create(struct devlink *devlink,
 					     u32 region_max_snapshots,
 					     u64 region_size);
 void devlink_region_destroy(struct devlink_region *region);
+u32 devlink_region_shapshot_id_get(struct devlink *devlink);
 
 #else
 
@@ -792,6 +794,12 @@ devlink_region_destroy(struct devlink_region *region)
 {
 }
 
+static inline u32
+devlink_region_shapshot_id_get(struct devlink *devlink)
+{
+	return 0;
+}
+
 #endif
 
 #endif /* _NET_DEVLINK_H_ */

net/core/devlink.c

@@ -4193,6 +4193,27 @@ void devlink_region_destroy(struct devlink_region *region)
 }
 EXPORT_SYMBOL_GPL(devlink_region_destroy);
 
+/**
+ *	devlink_region_shapshot_id_get - get snapshot ID
+ *
+ *	This callback should be called when adding a new snapshot,
+ *	Driver should use the same id for multiple snapshots taken
+ *	on multiple regions at the same time/by the same trigger.
+ *
+ *	@devlink: devlink
+ */
+u32 devlink_region_shapshot_id_get(struct devlink *devlink)
+{
+	u32 id;
+
+	mutex_lock(&devlink->lock);
+	id = ++devlink->snapshot_id;
+	mutex_unlock(&devlink->lock);
+
+	return id;
+}
+EXPORT_SYMBOL_GPL(devlink_region_shapshot_id_get);
+
 static int __init devlink_module_init(void)
 {
 	return genl_register_family(&devlink_nl_family);