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Commit cd9cb389 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'rtnetlink-allow-selected-handlers-to-run-without-rtnl' 



Florian Westphal says:

====================
rtnetlink: allow selected handlers to run without rtnl

Changes since v1:
 In patch 6, don't make ipv6 route handlers lockless, they all have
 assumptions on rtnl being held.  Other patches are unchanged.

The RTNL mutex is used to serialize both rtnetlink calls and
dump requests.
Its also used to protect other things such as the list of current
net namespaces.

Unfortunately RTNL mutex is a performance issue, e.g. a cpu adding an
ip address prevents other cpus from seemingly unrelated tasks such as
dumping tc classifiers or doing rtnetlink route lookups.

This patch set adds basic infrastructure to start pushing the rtnl lock
down to those places that need it, or even elide it entirely in some cases.

Subsystems can now indicate that their doit() callback can run without
RTNL mutex, such callbacks can then run in parallel.

This will obviously need a lot of followup work; all current
users need to be audited/changed to benefit from this.
Initial no-rtnl spot is netns new/getid.

We have various 'get' handlers that are also a tempting target,
however, several of these depend on rtnl mutex to prevent information
from changing while objects are being read by rtnl handlers; however,
it doesn't appear impossible to change this.

Dumps are another problem entirely, see
commit 2907c35f ("net: hold rtnl again in dump callbacks"),
this patchset doesn't touch dump requests.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 078295fb 165b9117

include/net/rtnetlink.h

+6 −3
Original line number Diff line number Diff line
@@ -7,12 +7,15 @@ 
typedef int (*rtnl_doit_func)(struct sk_buff *, struct nlmsghdr *,

			      struct netlink_ext_ack *);

typedef int (*rtnl_dumpit_func)(struct sk_buff *, struct netlink_callback *);

typedef u16 (*rtnl_calcit_func)(struct sk_buff *, struct nlmsghdr *);



enum rtnl_link_flags {

	RTNL_FLAG_DOIT_UNLOCKED = 1,

};



int __rtnl_register(int protocol, int msgtype,

		    rtnl_doit_func, rtnl_dumpit_func, rtnl_calcit_func);

		    rtnl_doit_func, rtnl_dumpit_func, unsigned int flags);

void rtnl_register(int protocol, int msgtype,

		   rtnl_doit_func, rtnl_dumpit_func, rtnl_calcit_func);

		   rtnl_doit_func, rtnl_dumpit_func, unsigned int flags);

int rtnl_unregister(int protocol, int msgtype);

void rtnl_unregister_all(int protocol);

net/bridge/br_mdb.c

+3 −3
Original line number Diff line number Diff line
@@ -713,9 +713,9 @@ static int br_mdb_del(struct sk_buff *skb, struct nlmsghdr *nlh, 


void br_mdb_init(void)

{

	rtnl_register(PF_BRIDGE, RTM_GETMDB, NULL, br_mdb_dump, NULL);

	rtnl_register(PF_BRIDGE, RTM_NEWMDB, br_mdb_add, NULL, NULL);

	rtnl_register(PF_BRIDGE, RTM_DELMDB, br_mdb_del, NULL, NULL);

	rtnl_register(PF_BRIDGE, RTM_GETMDB, NULL, br_mdb_dump, 0);

	rtnl_register(PF_BRIDGE, RTM_NEWMDB, br_mdb_add, NULL, 0);

	rtnl_register(PF_BRIDGE, RTM_DELMDB, br_mdb_del, NULL, 0);

}



void br_mdb_uninit(void)

net/can/gw.c

+3 −3
Original line number Diff line number Diff line
@@ -1031,15 +1031,15 @@ static __init int cgw_module_init(void) 
	notifier.notifier_call = cgw_notifier;

	register_netdevice_notifier(&notifier);



	if (__rtnl_register(PF_CAN, RTM_GETROUTE, NULL, cgw_dump_jobs, NULL)) {

	if (__rtnl_register(PF_CAN, RTM_GETROUTE, NULL, cgw_dump_jobs, 0)) {

		unregister_netdevice_notifier(&notifier);

		kmem_cache_destroy(cgw_cache);

		return -ENOBUFS;

	}



	/* Only the first call to __rtnl_register can fail */

	__rtnl_register(PF_CAN, RTM_NEWROUTE, cgw_create_job, NULL, NULL);

	__rtnl_register(PF_CAN, RTM_DELROUTE, cgw_remove_job, NULL, NULL);

	__rtnl_register(PF_CAN, RTM_NEWROUTE, cgw_create_job, NULL, 0);

	__rtnl_register(PF_CAN, RTM_DELROUTE, cgw_remove_job, NULL, 0);



	return 0;

}

net/core/fib_rules.c

+3 −3
Original line number Diff line number Diff line
@@ -1026,9 +1026,9 @@ static struct pernet_operations fib_rules_net_ops = { 
static int __init fib_rules_init(void)

{

	int err;

	rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL, NULL);

	rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL, NULL);

	rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule, NULL);

	rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL, 0);

	rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL, 0);

	rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule, 0);



	err = register_pernet_subsys(&fib_rules_net_ops);

	if (err < 0)

net/core/neighbour.c

+5 −5
Original line number Diff line number Diff line
@@ -3261,13 +3261,13 @@ EXPORT_SYMBOL(neigh_sysctl_unregister); 


static int __init neigh_init(void)

{

	rtnl_register(PF_UNSPEC, RTM_NEWNEIGH, neigh_add, NULL, NULL);

	rtnl_register(PF_UNSPEC, RTM_DELNEIGH, neigh_delete, NULL, NULL);

	rtnl_register(PF_UNSPEC, RTM_GETNEIGH, NULL, neigh_dump_info, NULL);

	rtnl_register(PF_UNSPEC, RTM_NEWNEIGH, neigh_add, NULL, 0);

	rtnl_register(PF_UNSPEC, RTM_DELNEIGH, neigh_delete, NULL, 0);

	rtnl_register(PF_UNSPEC, RTM_GETNEIGH, NULL, neigh_dump_info, 0);



	rtnl_register(PF_UNSPEC, RTM_GETNEIGHTBL, NULL, neightbl_dump_info,

		      NULL);

	rtnl_register(PF_UNSPEC, RTM_SETNEIGHTBL, neightbl_set, NULL, NULL);

		      0);

	rtnl_register(PF_UNSPEC, RTM_SETNEIGHTBL, neightbl_set, NULL, 0);



	return 0;

}