devlink: add by-instance dump infra

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>

diff --git a/net/devlink/devl_internal.h b/net/devlink/devl_internal.h
index 1e32bded7c8a0637d880342b9cf324ce5adc92d8..856954e4a02d0a3afad3426a9546f2e08866f550 100644 (file)
--- 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 registered devlink instances for devlink dump.
  * devlink_put() needs to be called for each iterated devlink pointer
  * in loop body in order to release the reference.
@@ -140,6 +145,9 @@ 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_nl_instance_iter_dump(struct sk_buff *msg,
+                                 struct netlink_callback *cb);
+
 static inline struct devlink_nl_dump_state *
 devlink_dump_state(struct netlink_callback *cb)
 {
@@ -175,6 +183,8 @@ 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 4c91143d0792c3418f93e6b7dd5f5fba30eb396e..6b5d60c91816304b67e552dfb17f51b3f5410e24 100644 (file)
--- 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_dump_one(struct sk_buff *msg, struct devlink *devlink,
+                                struct netlink_callback *cb)
 {
        struct devlink_nl_dump_state *state = devlink_dump_state(cb);
-       struct devlink *devlink;
+       struct devlink_rate *devlink_rate;
+       int idx = 0;
        int err = 0;
 
-       devlink_dump_for_each_instance_get(msg, state, 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 < state->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);
-                               state->idx = idx;
-                               goto out;
-                       }
+               if (idx < state->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) {
+                       state->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_dump_one,
+};
+
 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_nl_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 ce1a7d674d14770b99d1f1cd330075512aae4e3d..82ee5621bd9c320e5bc21ebc0b3aced5bbdc38ed 100644 (file)
--- 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 +178,39 @@ 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_nl_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 *state = devlink_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, state, 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 */
+               state->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,