[PATCH v4 1/3] genetlink: Add per family bind/unbind callbacks
From: Stanislaw Gruszka <hidden>
Date: 2024-02-12 16:16:34
Also in:
linux-pm
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Add genetlink family bind()/unbind() callbacks when adding/removing multicast group to/from netlink client socket via setsockopt() or bind() syscall. They can be used to track if consumers of netlink multicast messages emerge or disappear. Thus, a client implementing callbacks, can now send events only when there are active consumers, preventing unnecessary work when none exist. Suggested-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Stanislaw Gruszka <redacted> --- include/net/genetlink.h | 4 ++++ net/netlink/genetlink.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 34 insertions(+)
diff --git a/include/net/genetlink.h b/include/net/genetlink.h
index e61469129402..ecadba836ae5 100644
--- a/include/net/genetlink.h
+++ b/include/net/genetlink.h@@ -41,6 +41,8 @@ struct genl_info; * do additional, common, filtering and return an error * @post_doit: called after an operation's doit callback, it may * undo operations done by pre_doit, for example release locks + * @bind: called when family multicast group is added to a netlink socket + * @unbind: called when family multicast group is removed from a netlink socket * @module: pointer to the owning module (set to THIS_MODULE) * @mcgrps: multicast groups used by this family * @n_mcgrps: number of multicast groups
@@ -84,6 +86,8 @@ struct genl_family { void (*post_doit)(const struct genl_split_ops *ops, struct sk_buff *skb, struct genl_info *info); + int (*bind)(int mcgrp); + void (*unbind)(int mcgrp); const struct genl_ops * ops; const struct genl_small_ops *small_ops; const struct genl_split_ops *split_ops;
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 8c7af02f8454..50ec599a5cff 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c@@ -1836,6 +1836,9 @@ static int genl_bind(struct net *net, int group) !ns_capable(net->user_ns, CAP_SYS_ADMIN)) ret = -EPERM; + if (family->bind) + family->bind(i); + break; }
@@ -1843,12 +1846,39 @@ static int genl_bind(struct net *net, int group) return ret; } +static void genl_unbind(struct net *net, int group) +{ + const struct genl_family *family; + unsigned int id; + + down_read(&cb_lock); + + idr_for_each_entry(&genl_fam_idr, family, id) { + int i; + + if (family->n_mcgrps == 0) + continue; + + i = group - family->mcgrp_offset; + if (i < 0 || i >= family->n_mcgrps) + continue; + + if (family->unbind) + family->unbind(i); + + break; + } + + up_read(&cb_lock); +} + static int __net_init genl_pernet_init(struct net *net) { struct netlink_kernel_cfg cfg = { .input = genl_rcv, .flags = NL_CFG_F_NONROOT_RECV, .bind = genl_bind, + .unbind = genl_unbind, .release = genl_release, };
--
2.34.1