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devlink: let kernel allocate region snapshot id

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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: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Kicinski
2020-05-01 09:40:41 -07:00
committed by David S. Miller
parent dd86fec7e0
commit 043b3e2276
3 changed files with 62 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

57
net/core/devlink.c
View File

@@ -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) {
@@ -4119,17 +4116,26 @@ 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");
return -EEXIST;
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");
return -EEXIST;
}
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 = __devlink_snapshot_id_insert(devlink, snapshot_id);
if (err)
return err;
err = region->ops->snapshot(devlink, info->extack, &data);
if (err)
goto err_snapshot_capture;
@@ -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,