From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH net-next-2.6] garp: remove last synchronize_rcu() call Date: Thu, 12 May 2011 15:29:17 +0200 Message-ID: <1305206957.3795.21.camel@edumazet-laptop> References: <1304948155.3342.32.camel@edumazet-laptop> <4DC831B0.80107@trash.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: David Miller , Ben Greear , netdev , "Paul E. McKenney" To: Patrick McHardy Return-path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:59547 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757048Ab1ELN3c (ORCPT ); Thu, 12 May 2011 09:29:32 -0400 Received: by wwa36 with SMTP id 36so1763974wwa.1 for ; Thu, 12 May 2011 06:29:31 -0700 (PDT) In-Reply-To: <4DC831B0.80107@trash.net> Sender: netdev-owner@vger.kernel.org List-ID: Le lundi 09 mai 2011 =C3=A0 20:25 +0200, Patrick McHardy a =C3=A9crit : > Am 09.05.2011 15:35, schrieb Eric Dumazet: > > Speedup vlan dismantling in CONFIG_VLAN_8021Q_GVRP=3Dy cases, > > by using a call_rcu() to free the memory instead of waiting with > > expensive synchronize_rcu() [ while RTNL is held ] > >=20 > > Signed-off-by: Eric Dumazet > > Cc: Ben Greear > > Cc: Patrick McHardy > > Cc: Paul E. McKenney > > --- > > Note: I'll take care of using kfree_rcu() when available in net-nex= t-2.6 > >=20 >=20 > Looks good to me. >=20 Here is a followup on this patch, thanks ! [PATCH net-next-2.6] garp: remove last synchronize_rcu() call When removing last vlan from a device, garp_uninit_applicant() calls synchronize_rcu() to make sure no user can still manipulate struct garp_applicant before we free it. Use call_rcu() instead, as a step to further net_device dismantle optimizations. Add the temporary garp_cleanup_module() function to make sure no pendin= g call_rcu() are left at module unload time [ this will be removed when kfree_rcu() is available ] Signed-off-by: Eric Dumazet Cc: Patrick McHardy Cc: Paul E. McKenney Cc: Ben Greear --- include/net/garp.h | 1 + net/802/garp.c | 14 ++++++++++++-- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/include/net/garp.h b/include/net/garp.h index 8cabbf08..834d8ad 100644 --- a/include/net/garp.h +++ b/include/net/garp.h @@ -104,6 +104,7 @@ struct garp_applicant { struct sk_buff_head queue; struct sk_buff *pdu; struct rb_root gid; + struct rcu_head rcu; }; =20 struct garp_port { diff --git a/net/802/garp.c b/net/802/garp.c index 5dbe896..f8300a8 100644 --- a/net/802/garp.c +++ b/net/802/garp.c @@ -603,6 +603,11 @@ err1: } EXPORT_SYMBOL_GPL(garp_init_applicant); =20 +static void garp_app_kfree_rcu(struct rcu_head *head) +{ + kfree(container_of(head, struct garp_applicant, rcu)); +} + void garp_uninit_applicant(struct net_device *dev, struct garp_applica= tion *appl) { struct garp_port *port =3D rtnl_dereference(dev->garp_port); @@ -611,7 +616,6 @@ void garp_uninit_applicant(struct net_device *dev, = struct garp_application *appl ASSERT_RTNL(); =20 rcu_assign_pointer(port->applicants[appl->type], NULL); - synchronize_rcu(); =20 /* Delete timer and generate a final TRANSMIT_PDU event to flush out * all pending messages before the applicant is gone. */ @@ -621,7 +625,7 @@ void garp_uninit_applicant(struct net_device *dev, = struct garp_application *appl garp_queue_xmit(app); =20 dev_mc_del(dev, appl->proto.group_address); - kfree(app); + call_rcu(&app->rcu, garp_app_kfree_rcu); garp_release_port(dev); } EXPORT_SYMBOL_GPL(garp_uninit_applicant); @@ -639,3 +643,9 @@ void garp_unregister_application(struct garp_applic= ation *appl) stp_proto_unregister(&appl->proto); } EXPORT_SYMBOL_GPL(garp_unregister_application); + +static void __exit garp_cleanup_module(void) +{ + rcu_barrier(); /* Wait for completion of call_rcu()'s */ +} +module_exit(garp_cleanup_module);