From c749cdda9089eb1fdb6a9ab98f945124d12f2595 Mon Sep 17 00:00:00 2001 From: Davide Caratti Date: Wed, 11 Jul 2018 16:04:50 +0200 Subject: net/sched: act_skbedit: don't use spinlock in the data path use RCU instead of spin_{,un}lock_bh, to protect concurrent read/write on act_skbedit configuration. This reduces the effects of contention in the data path, in case multiple readers are present. Signed-off-by: Davide Caratti Signed-off-by: David S. Miller --- net/sched/act_skbedit.c | 107 ++++++++++++++++++++++++++++++------------------ 1 file changed, 68 insertions(+), 39 deletions(-) (limited to 'net/sched/act_skbedit.c') diff --git a/net/sched/act_skbedit.c b/net/sched/act_skbedit.c index 8651b5bd6b59..da56e6938c9e 100644 --- a/net/sched/act_skbedit.c +++ b/net/sched/act_skbedit.c @@ -37,14 +37,19 @@ static int tcf_skbedit(struct sk_buff *skb, const struct tc_action *a, struct tcf_result *res) { struct tcf_skbedit *d = to_skbedit(a); + struct tcf_skbedit_params *params; + int action; tcf_lastuse_update(&d->tcf_tm); bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb); - spin_lock(&d->tcf_lock); - if (d->flags & SKBEDIT_F_PRIORITY) - skb->priority = d->priority; - if (d->flags & SKBEDIT_F_INHERITDSFIELD) { + rcu_read_lock(); + params = rcu_dereference(d->params); + action = READ_ONCE(d->tcf_action); + + if (params->flags & SKBEDIT_F_PRIORITY) + skb->priority = params->priority; + if (params->flags & SKBEDIT_F_INHERITDSFIELD) { int wlen = skb_network_offset(skb); switch (tc_skb_protocol(skb)) { @@ -63,23 +68,23 @@ static int tcf_skbedit(struct sk_buff *skb, const struct tc_action *a, break; } } - if (d->flags & SKBEDIT_F_QUEUE_MAPPING && - skb->dev->real_num_tx_queues > d->queue_mapping) - skb_set_queue_mapping(skb, d->queue_mapping); - if (d->flags & SKBEDIT_F_MARK) { - skb->mark &= ~d->mask; - skb->mark |= d->mark & d->mask; + if (params->flags & SKBEDIT_F_QUEUE_MAPPING && + skb->dev->real_num_tx_queues > params->queue_mapping) + skb_set_queue_mapping(skb, params->queue_mapping); + if (params->flags & SKBEDIT_F_MARK) { + skb->mark &= ~params->mask; + skb->mark |= params->mark & params->mask; } - if (d->flags & SKBEDIT_F_PTYPE) - skb->pkt_type = d->ptype; - - spin_unlock(&d->tcf_lock); - return d->tcf_action; + if (params->flags & SKBEDIT_F_PTYPE) + skb->pkt_type = params->ptype; +unlock: + rcu_read_unlock(); + return action; err: - spin_unlock(&d->tcf_lock); qstats_drop_inc(this_cpu_ptr(d->common.cpu_qstats)); - return TC_ACT_SHOT; + action = TC_ACT_SHOT; + goto unlock; } static const struct nla_policy skbedit_policy[TCA_SKBEDIT_MAX + 1] = { @@ -98,6 +103,7 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla, struct netlink_ext_ack *extack) { struct tc_action_net *tn = net_generic(net, skbedit_net_id); + struct tcf_skbedit_params *params_old, *params_new; struct nlattr *tb[TCA_SKBEDIT_MAX + 1]; struct tc_skbedit *parm; struct tcf_skbedit *d; @@ -185,25 +191,34 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla, } } - spin_lock_bh(&d->tcf_lock); + ASSERT_RTNL(); - d->flags = flags; + params_new = kzalloc(sizeof(*params_new), GFP_KERNEL); + if (unlikely(!params_new)) { + if (ret == ACT_P_CREATED) + tcf_idr_release(*a, bind); + return -ENOMEM; + } + + params_new->flags = flags; if (flags & SKBEDIT_F_PRIORITY) - d->priority = *priority; + params_new->priority = *priority; if (flags & SKBEDIT_F_QUEUE_MAPPING) - d->queue_mapping = *queue_mapping; + params_new->queue_mapping = *queue_mapping; if (flags & SKBEDIT_F_MARK) - d->mark = *mark; + params_new->mark = *mark; if (flags & SKBEDIT_F_PTYPE) - d->ptype = *ptype; + params_new->ptype = *ptype; /* default behaviour is to use all the bits */ - d->mask = 0xffffffff; + params_new->mask = 0xffffffff; if (flags & SKBEDIT_F_MASK) - d->mask = *mask; + params_new->mask = *mask; d->tcf_action = parm->action; - - spin_unlock_bh(&d->tcf_lock); + params_old = rtnl_dereference(d->params); + rcu_assign_pointer(d->params, params_new); + if (params_old) + kfree_rcu(params_old, rcu); if (ret == ACT_P_CREATED) tcf_idr_insert(tn, *a); @@ -215,33 +230,36 @@ static int tcf_skbedit_dump(struct sk_buff *skb, struct tc_action *a, { unsigned char *b = skb_tail_pointer(skb); struct tcf_skbedit *d = to_skbedit(a); + struct tcf_skbedit_params *params; struct tc_skbedit opt = { .index = d->tcf_index, .refcnt = refcount_read(&d->tcf_refcnt) - ref, .bindcnt = atomic_read(&d->tcf_bindcnt) - bind, .action = d->tcf_action, }; - struct tcf_t t; u64 pure_flags = 0; + struct tcf_t t; + + params = rtnl_dereference(d->params); if (nla_put(skb, TCA_SKBEDIT_PARMS, sizeof(opt), &opt)) goto nla_put_failure; - if ((d->flags & SKBEDIT_F_PRIORITY) && - nla_put_u32(skb, TCA_SKBEDIT_PRIORITY, d->priority)) + if ((params->flags & SKBEDIT_F_PRIORITY) && + nla_put_u32(skb, TCA_SKBEDIT_PRIORITY, params->priority)) goto nla_put_failure; - if ((d->flags & SKBEDIT_F_QUEUE_MAPPING) && - nla_put_u16(skb, TCA_SKBEDIT_QUEUE_MAPPING, d->queue_mapping)) + if ((params->flags & SKBEDIT_F_QUEUE_MAPPING) && + nla_put_u16(skb, TCA_SKBEDIT_QUEUE_MAPPING, params->queue_mapping)) goto nla_put_failure; - if ((d->flags & SKBEDIT_F_MARK) && - nla_put_u32(skb, TCA_SKBEDIT_MARK, d->mark)) + if ((params->flags & SKBEDIT_F_MARK) && + nla_put_u32(skb, TCA_SKBEDIT_MARK, params->mark)) goto nla_put_failure; - if ((d->flags & SKBEDIT_F_PTYPE) && - nla_put_u16(skb, TCA_SKBEDIT_PTYPE, d->ptype)) + if ((params->flags & SKBEDIT_F_PTYPE) && + nla_put_u16(skb, TCA_SKBEDIT_PTYPE, params->ptype)) goto nla_put_failure; - if ((d->flags & SKBEDIT_F_MASK) && - nla_put_u32(skb, TCA_SKBEDIT_MASK, d->mask)) + if ((params->flags & SKBEDIT_F_MASK) && + nla_put_u32(skb, TCA_SKBEDIT_MASK, params->mask)) goto nla_put_failure; - if (d->flags & SKBEDIT_F_INHERITDSFIELD) + if (params->flags & SKBEDIT_F_INHERITDSFIELD) pure_flags |= SKBEDIT_F_INHERITDSFIELD; if (pure_flags != 0 && nla_put(skb, TCA_SKBEDIT_FLAGS, sizeof(pure_flags), &pure_flags)) @@ -257,6 +275,16 @@ nla_put_failure: return -1; } +static void tcf_skbedit_cleanup(struct tc_action *a) +{ + struct tcf_skbedit *d = to_skbedit(a); + struct tcf_skbedit_params *params; + + params = rcu_dereference_protected(d->params, 1); + if (params) + kfree_rcu(params, rcu); +} + static int tcf_skbedit_walker(struct net *net, struct sk_buff *skb, struct netlink_callback *cb, int type, const struct tc_action_ops *ops, @@ -289,6 +317,7 @@ static struct tc_action_ops act_skbedit_ops = { .act = tcf_skbedit, .dump = tcf_skbedit_dump, .init = tcf_skbedit_init, + .cleanup = tcf_skbedit_cleanup, .walk = tcf_skbedit_walker, .lookup = tcf_skbedit_search, .delete = tcf_skbedit_delete, -- cgit v1.2.3-59-g8ed1b