devlink: convert snapshot destructor callback to region op

It does not makes sense that two snapshots for a given region would use
different destructors. Simplify snapshot creation by adding
a .destructor op for regions.

This operation will replace the data_destructor for the snapshot
creation, and makes snapshot creation easier.

Noticed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/crdump.c

@@ -43,10 +43,12 @@ static const char * const region_fw_health_str = "fw-health";
 
 static const struct devlink_region_ops region_cr_space_ops = {
 	.name = region_cr_space_str,
+	.destructor = &kvfree,
 };
 
 static const struct devlink_region_ops region_fw_health_ops = {
 	.name = region_fw_health_str,
+	.destructor = &kvfree,
 };
 
 /* Set to true in case cr enable bit was set to true before crdump */
@@ -107,7 +109,7 @@ static void mlx4_crdump_collect_crspace(struct mlx4_dev *dev,
 					readl(cr_space + offset);
 
 		err = devlink_region_snapshot_create(crdump->region_crspace,
-						     crspace_data, id, &kvfree);
+						     crspace_data, id);
 		if (err) {
 			kvfree(crspace_data);
 			mlx4_warn(dev, "crdump: devlink create %s snapshot id %d err %d\n",
@@ -146,7 +148,7 @@ static void mlx4_crdump_collect_fw_health(struct mlx4_dev *dev,
 					readl(health_buf_start + offset);
 
 		err = devlink_region_snapshot_create(crdump->region_fw_health,
-						     health_data, id, &kvfree);
+						     health_data, id);
 		if (err) {
 			kvfree(health_data);
 			mlx4_warn(dev, "crdump: devlink create %s snapshot id %d err %d\n",

drivers/net/netdevsim/dev.c

@@ -56,7 +56,7 @@ static ssize_t nsim_dev_take_snapshot_write(struct file *file,
 
 	id = devlink_region_snapshot_id_get(priv_to_devlink(nsim_dev));
 	err = devlink_region_snapshot_create(nsim_dev->dummy_region,
-					     dummy_data, id, kfree);
+					     dummy_data, id);
 	if (err) {
 		pr_err("Failed to create region snapshot\n");
 		kfree(dummy_data);
@@ -342,6 +342,7 @@ static void nsim_devlink_param_load_driverinit_values(struct devlink *devlink)
 
 static const struct devlink_region_ops dummy_region_ops = {
 	.name = "dummy",
+	.destructor = &kfree,
 };
 
 static int nsim_dev_dummy_region_init(struct nsim_dev *nsim_dev,

include/net/devlink.h

@@ -496,14 +496,14 @@ enum devlink_param_generic_id {
 struct devlink_region;
 struct devlink_info_req;
 
-typedef void devlink_snapshot_data_dest_t(const void *data);
-
 /**
  * struct devlink_region_ops - Region operations
  * @name: region name
+ * @destructor: callback used to free snapshot memory when deleting
  */
 struct devlink_region_ops {
 	const char *name;
+	void (*destructor)(const void *data);
 };
 
 struct devlink_fmsg;
@@ -978,8 +978,7 @@ devlink_region_create(struct devlink *devlink,
 void devlink_region_destroy(struct devlink_region *region);
 u32 devlink_region_snapshot_id_get(struct devlink *devlink);
 int devlink_region_snapshot_create(struct devlink_region *region,
-				   u8 *data, u32 snapshot_id,
-				   devlink_snapshot_data_dest_t *data_destructor);
+				   u8 *data, u32 snapshot_id);
 int devlink_info_serial_number_put(struct devlink_info_req *req,
 				   const char *sn);
 int devlink_info_driver_name_put(struct devlink_info_req *req,

net/core/devlink.c

@@ -354,7 +354,6 @@ struct devlink_region {
 struct devlink_snapshot {
 	struct list_head list;
 	struct devlink_region *region;
-	devlink_snapshot_data_dest_t *data_destructor;
 	u8 *data;
 	u32 id;
 };
@@ -3775,7 +3774,7 @@ static void devlink_region_snapshot_del(struct devlink_region *region,
 	devlink_nl_region_notify(region, snapshot, DEVLINK_CMD_REGION_DEL);
 	region->cur_snapshots--;
 	list_del(&snapshot->list);
-	(*snapshot->data_destructor)(snapshot->data);
+	region->ops->destructor(snapshot->data);
 	kfree(snapshot);
 }
 
@@ -7660,6 +7659,9 @@ devlink_region_create(struct devlink *devlink,
 	struct devlink_region *region;
 	int err = 0;
 
+	if (WARN_ON(!ops) || WARN_ON(!ops->destructor))
+		return ERR_PTR(-EINVAL);
+
 	mutex_lock(&devlink->lock);
 
 	if (devlink_region_get_by_name(devlink, ops->name)) {
@@ -7746,11 +7748,9 @@ EXPORT_SYMBOL_GPL(devlink_region_snapshot_id_get);
  *	@region: devlink region of the snapshot
  *	@data: snapshot data
  *	@snapshot_id: snapshot id to be created
- *	@data_destructor: pointer to destructor function to free data
  */
 int devlink_region_snapshot_create(struct devlink_region *region,
-				   u8 *data, u32 snapshot_id,
-				   devlink_snapshot_data_dest_t *data_destructor)
+				   u8 *data, u32 snapshot_id)
 {
 	struct devlink *devlink = region->devlink;
 	struct devlink_snapshot *snapshot;
@@ -7778,7 +7778,6 @@ int devlink_region_snapshot_create(struct devlink_region *region,
 	snapshot->id = snapshot_id;
 	snapshot->region = region;
 	snapshot->data = data;
-	snapshot->data_destructor = data_destructor;
 
 	list_add_tail(&snapshot->list, &region->snapshot_list);