[PATCH v2 3/3] netdevsim: support triggering snapshot through devlink

[Jacob Keller <jacob.e.keller@intel.com>]

Implement the trigger_snapshot callback for the dummy devlink region.
This enables the region snapshot to be requested directly through the
devlink API instead of using debugfs as an out-of-band mechanism for
triggering the snapshot.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
---
 drivers/net/netdevsim/dev.c | 36 ++++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index 2af97eeb7ba1..4ed9c8d8de7c 100644
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c
@@ -38,30 +38,46 @@ static struct dentry *nsim_dev_ddir;
 
 #define NSIM_DEV_DUMMY_REGION_SIZE (1024 * 32)
 
-static ssize_t nsim_dev_take_snapshot_write(struct file *file,
-					    const char __user *data,
-					    size_t count, loff_t *ppos)
+static int nsim_dev_trigger_snapshot(struct devlink *devlink,
+				     struct devlink_region *region,
+				     struct netlink_ext_ack *extack)
 {
-	struct nsim_dev *nsim_dev = file->private_data;
 	void *dummy_data;
 	int err;
 	u32 id;
 
 	dummy_data = kmalloc(NSIM_DEV_DUMMY_REGION_SIZE, GFP_KERNEL);
-	if (!dummy_data)
+	if (!dummy_data) {
+		NL_SET_ERR_MSG(extack, "Out of memory");
 		return -ENOMEM;
+	}
 
 	get_random_bytes(dummy_data, NSIM_DEV_DUMMY_REGION_SIZE);
 
-	id = devlink_region_snapshot_id_get(priv_to_devlink(nsim_dev));
-	err = devlink_region_snapshot_create(nsim_dev->dummy_region,
-					     dummy_data, id, kfree);
+	id = devlink_region_snapshot_id_get(devlink);
+	err = devlink_region_snapshot_create(region, dummy_data, id, kfree);
 	if (err) {
-		pr_err("Failed to create region snapshot\n");
+		NL_SET_ERR_MSG(extack, "Failed to create region snapshot");
 		kfree(dummy_data);
 		return err;
 	}
 
+	return (0);
+
+}
+
+static ssize_t nsim_dev_take_snapshot_write(struct file *file,
+					    const char __user *data,
+					    size_t count, loff_t *ppos)
+{
+	struct nsim_dev *nsim_dev = file->private_data;
+	int err;
+
+	err = nsim_dev_trigger_snapshot(priv_to_devlink(nsim_dev),
+					nsim_dev->dummy_region, NULL);
+	if (err)
+		return err;
+
 	return count;
 }
 
@@ -249,7 +265,7 @@ static int nsim_dev_dummy_region_init(struct nsim_dev *nsim_dev,
 		devlink_region_create(devlink, "dummy",
 				      NSIM_DEV_DUMMY_REGION_SNAPSHOT_MAX,
 				      NSIM_DEV_DUMMY_REGION_SIZE,
-				      NULL);
+				      nsim_dev_trigger_snapshot);
 	return PTR_ERR_OR_ZERO(nsim_dev->dummy_region);
 }
 
-- 
2.25.0.rc1