From 25d8c0d55f241ce2d360df1bea48e23a55836ee6 Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Fri, 12 Sep 2014 20:05:27 -0700 Subject: net: rcu-ify tcf_proto rcu'ify tcf_proto this allows calling tc_classify() without holding any locks. Updaters are protected by RTNL. This patch prepares the core net_sched infrastracture for running the classifier/action chains without holding the qdisc lock however it does nothing to ensure cls_xxx and act_xxx types also work without locking. Additional patches are required to address the fall out. Signed-off-by: John Fastabend Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/sched/cls_api.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) (limited to 'net/sched/cls_api.c') diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index c28b0d327b12..e547efdaba9d 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -117,7 +117,6 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n) { struct net *net = sock_net(skb->sk); struct nlattr *tca[TCA_MAX + 1]; - spinlock_t *root_lock; struct tcmsg *t; u32 protocol; u32 prio; @@ -125,7 +124,8 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n) u32 parent; struct net_device *dev; struct Qdisc *q; - struct tcf_proto **back, **chain; + struct tcf_proto __rcu **back; + struct tcf_proto __rcu **chain; struct tcf_proto *tp; const struct tcf_proto_ops *tp_ops; const struct Qdisc_class_ops *cops; @@ -197,7 +197,9 @@ replay: goto errout; /* Check the chain for existence of proto-tcf with this priority */ - for (back = chain; (tp = *back) != NULL; back = &tp->next) { + for (back = chain; + (tp = rtnl_dereference(*back)) != NULL; + back = &tp->next) { if (tp->prio >= prio) { if (tp->prio == prio) { if (!nprio || @@ -209,8 +211,6 @@ replay: } } - root_lock = qdisc_root_sleeping_lock(q); - if (tp == NULL) { /* Proto-tcf does not exist, create new one */ @@ -259,7 +259,8 @@ replay: } tp->ops = tp_ops; tp->protocol = protocol; - tp->prio = nprio ? : TC_H_MAJ(tcf_auto_prio(*back)); + tp->prio = nprio ? : + TC_H_MAJ(tcf_auto_prio(rtnl_dereference(*back))); tp->q = q; tp->classify = tp_ops->classify; tp->classid = parent; @@ -280,9 +281,9 @@ replay: if (fh == 0) { if (n->nlmsg_type == RTM_DELTFILTER && t->tcm_handle == 0) { - spin_lock_bh(root_lock); - *back = tp->next; - spin_unlock_bh(root_lock); + struct tcf_proto *next = rtnl_dereference(tp->next); + + RCU_INIT_POINTER(*back, next); tfilter_notify(net, skb, n, tp, fh, RTM_DELTFILTER); tcf_destroy(tp); @@ -322,10 +323,8 @@ replay: n->nlmsg_flags & NLM_F_CREATE ? TCA_ACT_NOREPLACE : TCA_ACT_REPLACE); if (err == 0) { if (tp_created) { - spin_lock_bh(root_lock); - tp->next = *back; - *back = tp; - spin_unlock_bh(root_lock); + RCU_INIT_POINTER(tp->next, rtnl_dereference(*back)); + rcu_assign_pointer(*back, tp); } tfilter_notify(net, skb, n, tp, fh, RTM_NEWTFILTER); } else { @@ -420,7 +419,7 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb) int s_t; struct net_device *dev; struct Qdisc *q; - struct tcf_proto *tp, **chain; + struct tcf_proto *tp, __rcu **chain; struct tcmsg *tcm = nlmsg_data(cb->nlh); unsigned long cl = 0; const struct Qdisc_class_ops *cops; @@ -454,7 +453,8 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb) s_t = cb->args[0]; - for (tp = *chain, t = 0; tp; tp = tp->next, t++) { + for (tp = rtnl_dereference(*chain), t = 0; + tp; tp = rtnl_dereference(tp->next), t++) { if (t < s_t) continue; if (TC_H_MAJ(tcm->tcm_info) && -- cgit v1.2.3-58-ga151