[PATCH net-next 13/14] devlink: add by-instance dump infra

Jakub Kicinski
2023-01-04T04:17:19Z

Most dumpit implementations walk the devlink instances.
This requires careful lock taking and reference dropping.
Factor the loop out and provide just a callback to handle
a single instance dump.

Convert one user as an example, other users converted
in the next change.

Slightly inspired by ethtool netlink code.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
net/devlink/devl_internal.h | 10 +++++++
net/devlink/leftover.c | 55 ++++++++++++++++---------------------
net/devlink/netlink.c | 33 ++++++++++++++++++++++
3 files changed, 67 insertions(+), 31 deletions(-)

diff --git a/net/devlink/devl_internal.h b/net/devlink/devl_internal.h
index 5adac38454fd..e49b82dd77cd 100644
--- a/net/devlink/devl_internal.h
+++ b/net/devlink/devl_internal.h
@@ -122,6 +122,11 @@ struct devlink_nl_dump_state {
};
};

+struct devlink_gen_cmd {
+ int (*dump_one)(struct sk_buff *msg, struct devlink *devlink,
+ struct netlink_callback *cb);
+};
+
/* Iterate over devlink pointers which were possible to get reference to.
* devlink_put() needs to be called for each iterated devlink pointer
* in loop body in order to release the reference.
@@ -138,6 +143,9 @@ struct devlink *devlink_get_from_attrs(struct net *net, struct nlattr **attrs);
void devlink_notify_unregister(struct devlink *devlink);
void devlink_notify_register(struct devlink *devlink);

+int devlink_instance_iter_dump(struct sk_buff *msg,
+ struct netlink_callback *cb);
+
static inline struct devlink_nl_dump_state *
devl_dump_state(struct netlink_callback *cb)
{
@@ -173,6 +181,8 @@ devlink_linecard_get_from_info(struct devlink *devlink, struct genl_info *info);
void devlink_linecard_put(struct devlink_linecard *linecard);

/* Rates */
+extern const struct devlink_gen_cmd devl_gen_rate_get;
+
struct devlink_rate *
devlink_rate_get_from_info(struct devlink *devlink, struct genl_info *info);
struct devlink_rate *
diff --git a/net/devlink/leftover.c b/net/devlink/leftover.c
index c6ad8133fc23..f18d8dcf9751 100644
--- a/net/devlink/leftover.c
+++ b/net/devlink/leftover.c
@@ -1219,47 +1219,40 @@ static void devlink_rate_notify(struct devlink_rate *devlink_rate,
0, DEVLINK_MCGRP_CONFIG, GFP_KERNEL);
}

-static int devlink_nl_cmd_rate_get_dumpit(struct sk_buff *msg,
- struct netlink_callback *cb)
+static int
+devlink_nl_cmd_rate_get_dumpinst(struct sk_buff *msg, struct devlink *devlink,
+ struct netlink_callback *cb)
{
struct devlink_nl_dump_state *dump = devl_dump_state(cb);
- struct devlink *devlink;
+ struct devlink_rate *devlink_rate;
+ int idx = 0;
int err = 0;

- devlink_dump_for_each_instance_get(msg, dump, devlink) {
- struct devlink_rate *devlink_rate;
- int idx = 0;
-
- devl_lock(devlink);
- list_for_each_entry(devlink_rate, &devlink->rate_list, list) {
- enum devlink_command cmd = DEVLINK_CMD_RATE_NEW;
- u32 id = NETLINK_CB(cb->skb).portid;
+ list_for_each_entry(devlink_rate, &devlink->rate_list, list) {
+ enum devlink_command cmd = DEVLINK_CMD_RATE_NEW;
+ u32 id = NETLINK_CB(cb->skb).portid;

- if (idx < dump->idx) {
- idx++;
- continue;
- }
- err = devlink_nl_rate_fill(msg, devlink_rate, cmd, id,
- cb->nlh->nlmsg_seq,
- NLM_F_MULTI, NULL);
- if (err) {
- devl_unlock(devlink);
- devlink_put(devlink);
- dump->idx = idx;
- goto out;
- }
+ if (idx < dump->idx) {
idx++;
+ continue;
}
- devl_unlock(devlink);
- devlink_put(devlink);
+ err = devlink_nl_rate_fill(msg, devlink_rate, cmd, id,
+ cb->nlh->nlmsg_seq,
+ NLM_F_MULTI, NULL);
+ if (err) {
+ dump->idx = idx;
+ break;
+ }
+ idx++;
}
-out:
- if (err != -EMSGSIZE)
- return err;

- return msg->len;
+ return err;
}

+const struct devlink_gen_cmd devl_gen_rate_get = {
+ .dump_one = devlink_nl_cmd_rate_get_dumpinst,
+};
+
static int devlink_nl_cmd_rate_get_doit(struct sk_buff *skb,
struct genl_info *info)
{
@@ -9130,7 +9123,7 @@ const struct genl_small_ops devlink_nl_ops[56] = {
{
.cmd = DEVLINK_CMD_RATE_GET,
.doit = devlink_nl_cmd_rate_get_doit,
- .dumpit = devlink_nl_cmd_rate_get_dumpit,
+ .dumpit = devlink_instance_iter_dump,
.internal_flags = DEVLINK_NL_FLAG_NEED_RATE,
/* can be retrieved by unprivileged users */
},
diff --git a/net/devlink/netlink.c b/net/devlink/netlink.c
index ce1a7d674d14..fcf10c288480 100644
--- a/net/devlink/netlink.c
+++ b/net/devlink/netlink.c
@@ -5,6 +5,7 @@
*/

#include <net/genetlink.h>
+#include <net/sock.h>

#include "devl_internal.h"

@@ -177,6 +178,38 @@ static void devlink_nl_post_doit(const struct genl_split_ops *ops,
devlink_put(devlink);
}

+static const struct devlink_gen_cmd *devl_gen_cmds[] = {
+ [DEVLINK_CMD_RATE_GET] = &devl_gen_rate_get,
+};
+
+int devlink_instance_iter_dump(struct sk_buff *msg, struct netlink_callback *cb)
+{
+ const struct genl_dumpit_info *info = genl_dumpit_info(cb);
+ struct devlink_nl_dump_state *dump = devl_dump_state(cb);
+ const struct devlink_gen_cmd *cmd;
+ struct devlink *devlink;
+ int err = 0;
+
+ cmd = devl_gen_cmds[info->op.cmd];
+
+ devlink_dump_for_each_instance_get(msg, dump, devlink) {
+ devl_lock(devlink);
+ err = cmd->dump_one(msg, devlink, cb);
+ devl_unlock(devlink);
+ devlink_put(devlink);
+
+ if (err)
+ break;
+
+ /* restart sub-object walk for the next instance */
+ dump->idx = 0;
+ }
+
+ if (err != -EMSGSIZE)
+ return err;
+ return msg->len;
+}
+
struct genl_family devlink_nl_family __ro_after_init = {
.name = DEVLINK_GENL_NAME,
.version = DEVLINK_GENL_VERSION,
--
2.38.1