From c5e2a973448d958feb7881e4d875eac59fdeff3d Mon Sep 17 00:00:00 2001 From: Jamal Hadi Salim Date: Fri, 8 Dec 2023 16:28:41 -0300 Subject: rtnl: add helper to check if rtnl group has listeners As of today, rtnl code creates a new skb and unconditionally fills and broadcasts it to the relevant group. For most operations this is okay and doesn't waste resources in general. When operations are done without the rtnl_lock, as in tc-flower, such skb allocation, message fill and no-op broadcasting can happen in all cores of the system, which contributes to system pressure and wastes precious cpu cycles when no one will receive the built message. Introduce this helper so rtnetlink operations can simply check if someone is listening and then proceed if necessary. Reviewed-by: Jiri Pirko Reviewed-by: Simon Horman Signed-off-by: Jamal Hadi Salim Signed-off-by: Victor Nogueira Signed-off-by: Pedro Tammela Link: https://lore.kernel.org/r/20231208192847.714940-2-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski --- include/linux/rtnetlink.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux') diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index 3d6cf306cd55..a7d757e96c55 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -130,4 +130,11 @@ extern int ndo_dflt_bridge_getlink(struct sk_buff *skb, u32 pid, u32 seq, extern void rtnl_offload_xstats_notify(struct net_device *dev); +static inline int rtnl_has_listeners(const struct net *net, u32 group) +{ + struct sock *rtnl = net->rtnl; + + return netlink_has_listeners(rtnl, group); +} + #endif /* __LINUX_RTNETLINK_H */ -- cgit v1.2.3 From 8439109b76a3c405808383bf9dd532fc4b9c2dbd Mon Sep 17 00:00:00 2001 From: Victor Nogueira Date: Fri, 8 Dec 2023 16:28:42 -0300 Subject: rtnl: add helper to check if a notification is needed Building on the rtnl_has_listeners helper, add the rtnl_notify_needed helper to check if we can bail out early in the notification routines. Reviewed-by: Jiri Pirko Reviewed-by: Simon Horman Signed-off-by: Victor Nogueira Signed-off-by: Pedro Tammela Link: https://lore.kernel.org/r/20231208192847.714940-3-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski --- include/linux/rtnetlink.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/linux') diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index a7d757e96c55..0cbbbded0331 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -137,4 +137,19 @@ static inline int rtnl_has_listeners(const struct net *net, u32 group) return netlink_has_listeners(rtnl, group); } +/** + * rtnl_notify_needed - check if notification is needed + * @net: Pointer to the net namespace + * @nlflags: netlink ingress message flags + * @group: rtnl group + * + * Based on the ingress message flags and rtnl group, returns true + * if a notification is needed, false otherwise. + */ +static inline bool +rtnl_notify_needed(const struct net *net, u16 nlflags, u32 group) +{ + return (nlflags & NLM_F_ECHO) || rtnl_has_listeners(net, group); +} + #endif /* __LINUX_RTNETLINK_H */ -- cgit v1.2.3 From ddb6b284bdc32b6e218b3d90b5a745ea26620812 Mon Sep 17 00:00:00 2001 From: Pedro Tammela Date: Fri, 8 Dec 2023 16:28:43 -0300 Subject: rtnl: add helper to send if skb is not null This is a convenience helper for routines handling conditional rtnl events, that is code that might send a notification depending on rtnl_has_listeners/rtnl_notify_needed. Instead of: if (skb) rtnetlink_send(...) Use: rtnetlink_maybe_send(...) Reviewed-by: Jiri Pirko Reviewed-by: Simon Horman Signed-off-by: Pedro Tammela Link: https://lore.kernel.org/r/20231208192847.714940-4-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski --- include/linux/rtnetlink.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux') diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index 0cbbbded0331..6a8543b34e2c 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -10,6 +10,13 @@ #include extern int rtnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, u32 group, int echo); + +static inline int rtnetlink_maybe_send(struct sk_buff *skb, struct net *net, + u32 pid, u32 group, int echo) +{ + return !skb ? 0 : rtnetlink_send(skb, net, pid, group, echo); +} + extern int rtnl_unicast(struct sk_buff *skb, struct net *net, u32 pid); extern void rtnl_notify(struct sk_buff *skb, struct net *net, u32 pid, u32 group, const struct nlmsghdr *nlh, gfp_t flags); -- cgit v1.2.3