Commit 043b3e22 authored by Jakub Kicinski's avatar Jakub Kicinski Committed by David S. Miller
Browse files

devlink: let kernel allocate region snapshot id 



Currently users have to choose a free snapshot id before
calling DEVLINK_CMD_REGION_NEW. This is potentially racy
and inconvenient.

Make the DEVLINK_ATTR_REGION_SNAPSHOT_ID optional and try
to allocate id automatically. Send a message back to the
caller with the snapshot info.

Example use:
$ devlink region new netdevsim/netdevsim1/dummy
netdevsim/netdevsim1/dummy: snapshot 1

$ id=$(devlink -j region new netdevsim/netdevsim1/dummy | \
       jq '.[][][][]')
$ devlink region dump netdevsim/netdevsim1/dummy snapshot $id
[...]
$ devlink region del netdevsim/netdevsim1/dummy snapshot $id

v4:
 - inline the notification code
v3:
 - send the notification only once snapshot creation completed.
v2:
 - don't wrap the line containing extack;
 - add a few sentences to the docs.

Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Reviewed-by: default avatarJacob Keller <jacob.e.keller@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent dd86fec7

Documentation/networking/devlink/devlink-region.rst

+5 −2
Original line number Diff line number Diff line
@@ -23,7 +23,9 @@ states, but see also :doc:`devlink-health` 
Regions may optionally support capturing a snapshot on demand via the

``DEVLINK_CMD_REGION_NEW`` netlink message. A driver wishing to allow

requested snapshots must implement the ``.snapshot`` callback for the region

in its ``devlink_region_ops`` structure.

in its ``devlink_region_ops`` structure. If snapshot id is not set in

the ``DEVLINK_CMD_REGION_NEW`` request kernel will allocate one and send

the snapshot information to user space.



example usage

-------------
@@ -45,7 +47,8 @@ example usage 
    $ devlink region del pci/0000:00:05.0/cr-space snapshot 1



    # Request an immediate snapshot, if supported by the region

    $ devlink region new pci/0000:00:05.0/cr-space snapshot 5

    $ devlink region new pci/0000:00:05.0/cr-space

    pci/0000:00:05.0/cr-space: snapshot 5



    # Dump a snapshot:

    $ devlink region dump pci/0000:00:05.0/fw-health snapshot 1

net/core/devlink.c

+44 −13
Original line number Diff line number Diff line
@@ -4086,6 +4086,8 @@ static int 
devlink_nl_cmd_region_new(struct sk_buff *skb, struct genl_info *info)

{

	struct devlink *devlink = info->user_ptr[0];

	struct devlink_snapshot *snapshot;

	struct nlattr *snapshot_id_attr;

	struct devlink_region *region;

	const char *region_name;

	u32 snapshot_id;
@@ -4097,11 +4099,6 @@ devlink_nl_cmd_region_new(struct sk_buff *skb, struct genl_info *info) 
		return -EINVAL;

	}



	if (!info->attrs[DEVLINK_ATTR_REGION_SNAPSHOT_ID]) {

		NL_SET_ERR_MSG_MOD(info->extack, "No snapshot id provided");

		return -EINVAL;

	}



	region_name = nla_data(info->attrs[DEVLINK_ATTR_REGION_NAME]);

	region = devlink_region_get_by_name(devlink, region_name);

	if (!region) {
@@ -4119,7 +4116,9 @@ devlink_nl_cmd_region_new(struct sk_buff *skb, struct genl_info *info) 
		return -ENOSPC;

	}



	snapshot_id = nla_get_u32(info->attrs[DEVLINK_ATTR_REGION_SNAPSHOT_ID]);

	snapshot_id_attr = info->attrs[DEVLINK_ATTR_REGION_SNAPSHOT_ID];

	if (snapshot_id_attr) {

		snapshot_id = nla_get_u32(snapshot_id_attr);



		if (devlink_region_snapshot_get_by_id(region, snapshot_id)) {

			NL_SET_ERR_MSG_MOD(info->extack, "The requested snapshot id is already in use");
@@ -4129,6 +4128,13 @@ devlink_nl_cmd_region_new(struct sk_buff *skb, struct genl_info *info) 
		err = __devlink_snapshot_id_insert(devlink, snapshot_id);

		if (err)

			return err;

	} else {

		err = __devlink_region_snapshot_id_get(devlink, &snapshot_id);

		if (err) {

			NL_SET_ERR_MSG_MOD(info->extack, "Failed to allocate a new snapshot id");

			return err;

		}

	}



	err = region->ops->snapshot(devlink, info->extack, &data);

	if (err)
@@ -4138,6 +4144,27 @@ devlink_nl_cmd_region_new(struct sk_buff *skb, struct genl_info *info) 
	if (err)

		goto err_snapshot_create;



	if (!snapshot_id_attr) {

		struct sk_buff *msg;



		snapshot = devlink_region_snapshot_get_by_id(region,

							     snapshot_id);

		if (WARN_ON(!snapshot))

			return -EINVAL;



		msg = devlink_nl_region_notify_build(region, snapshot,

						     DEVLINK_CMD_REGION_NEW,

						     info->snd_portid,

						     info->snd_seq);

		err = PTR_ERR_OR_ZERO(msg);

		if (err)

			goto err_notify;



		err = genlmsg_reply(msg, info);

		if (err)

			goto err_notify;

	}



	return 0;



err_snapshot_create:
@@ -4145,6 +4172,10 @@ err_snapshot_create: 
err_snapshot_capture:

	__devlink_snapshot_id_decrement(devlink, snapshot_id);

	return err;



err_notify:

	devlink_region_snapshot_del(region, snapshot);

	return err;

}



static int devlink_nl_cmd_region_read_chunk_fill(struct sk_buff *msg,

tools/testing/selftests/drivers/net/netdevsim/devlink.sh

+13 −0
Original line number Diff line number Diff line
@@ -151,6 +151,19 @@ regions_test() 


	check_region_snapshot_count dummy post-second-delete 2



	sid=$(devlink -j region new $DL_HANDLE/dummy | jq '.[][][][]')

	check_err $? "Failed to create a new snapshot with id allocated by the kernel"



	check_region_snapshot_count dummy post-first-request 3



	devlink region dump $DL_HANDLE/dummy snapshot $sid >> /dev/null

	check_err $? "Failed to dump a snapshot with id allocated by the kernel"



	devlink region del $DL_HANDLE/dummy snapshot $sid

	check_err $? "Failed to delete snapshot with id allocated by the kernel"



	check_region_snapshot_count dummy post-first-request 2



	log_test "regions test"

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE