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net: sched: use Qdisc rcu API instead of relying on rtnl lock
As a preparation from removing rtnl lock dependency from rules update path, use Qdisc rcu and reference counting capabilities instead of relying on rtnl lock while working with Qdiscs. Create new tcf_block_release() function, and use it to free resources taken by tcf_block_find(). Currently, this function only releases Qdisc and it is extended in next patches in this series. Signed-off-by: Vlad Buslov <vladbu@mellanox.com> Acked-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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parent
9d7e82cec3
commit
e368fdb61d
@ -537,6 +537,7 @@ static struct tcf_block *tcf_block_find(struct net *net, struct Qdisc **q,
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struct netlink_ext_ack *extack)
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{
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struct tcf_block *block;
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int err = 0;
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if (ifindex == TCM_IFINDEX_MAGIC_BLOCK) {
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block = tcf_block_lookup(net, block_index);
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@ -548,55 +549,93 @@ static struct tcf_block *tcf_block_find(struct net *net, struct Qdisc **q,
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const struct Qdisc_class_ops *cops;
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struct net_device *dev;
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rcu_read_lock();
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/* Find link */
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dev = __dev_get_by_index(net, ifindex);
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if (!dev)
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dev = dev_get_by_index_rcu(net, ifindex);
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if (!dev) {
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rcu_read_unlock();
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return ERR_PTR(-ENODEV);
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}
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/* Find qdisc */
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if (!*parent) {
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*q = dev->qdisc;
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*parent = (*q)->handle;
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} else {
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*q = qdisc_lookup(dev, TC_H_MAJ(*parent));
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*q = qdisc_lookup_rcu(dev, TC_H_MAJ(*parent));
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if (!*q) {
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NL_SET_ERR_MSG(extack, "Parent Qdisc doesn't exists");
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return ERR_PTR(-EINVAL);
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err = -EINVAL;
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goto errout_rcu;
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}
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}
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*q = qdisc_refcount_inc_nz(*q);
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if (!*q) {
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NL_SET_ERR_MSG(extack, "Parent Qdisc doesn't exists");
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err = -EINVAL;
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goto errout_rcu;
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}
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/* Is it classful? */
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cops = (*q)->ops->cl_ops;
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if (!cops) {
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NL_SET_ERR_MSG(extack, "Qdisc not classful");
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return ERR_PTR(-EINVAL);
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err = -EINVAL;
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goto errout_rcu;
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}
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if (!cops->tcf_block) {
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NL_SET_ERR_MSG(extack, "Class doesn't support blocks");
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return ERR_PTR(-EOPNOTSUPP);
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err = -EOPNOTSUPP;
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goto errout_rcu;
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}
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/* At this point we know that qdisc is not noop_qdisc,
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* which means that qdisc holds a reference to net_device
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* and we hold a reference to qdisc, so it is safe to release
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* rcu read lock.
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*/
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rcu_read_unlock();
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/* Do we search for filter, attached to class? */
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if (TC_H_MIN(*parent)) {
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*cl = cops->find(*q, *parent);
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if (*cl == 0) {
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NL_SET_ERR_MSG(extack, "Specified class doesn't exist");
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return ERR_PTR(-ENOENT);
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err = -ENOENT;
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goto errout_qdisc;
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}
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}
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/* And the last stroke */
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block = cops->tcf_block(*q, *cl, extack);
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if (!block)
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return ERR_PTR(-EINVAL);
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if (!block) {
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err = -EINVAL;
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goto errout_qdisc;
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}
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if (tcf_block_shared(block)) {
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NL_SET_ERR_MSG(extack, "This filter block is shared. Please use the block index to manipulate the filters");
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return ERR_PTR(-EOPNOTSUPP);
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err = -EOPNOTSUPP;
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goto errout_qdisc;
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}
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}
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return block;
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errout_rcu:
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rcu_read_unlock();
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errout_qdisc:
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if (*q)
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qdisc_put(*q);
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return ERR_PTR(err);
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}
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static void tcf_block_release(struct Qdisc *q, struct tcf_block *block)
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{
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if (q)
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qdisc_put(q);
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}
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struct tcf_block_owner_item {
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@ -1332,6 +1371,7 @@ replay:
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errout:
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if (chain)
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tcf_chain_put(chain);
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tcf_block_release(q, block);
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if (err == -EAGAIN)
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/* Replay the request. */
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goto replay;
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@ -1453,6 +1493,7 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
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errout:
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if (chain)
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tcf_chain_put(chain);
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tcf_block_release(q, block);
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return err;
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}
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@ -1538,6 +1579,7 @@ static int tc_get_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
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errout:
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if (chain)
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tcf_chain_put(chain);
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tcf_block_release(q, block);
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return err;
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}
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@ -1854,7 +1896,8 @@ replay:
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chain_index = tca[TCA_CHAIN] ? nla_get_u32(tca[TCA_CHAIN]) : 0;
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if (chain_index > TC_ACT_EXT_VAL_MASK) {
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NL_SET_ERR_MSG(extack, "Specified chain index exceeds upper limit");
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return -EINVAL;
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err = -EINVAL;
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goto errout_block;
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}
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chain = tcf_chain_lookup(block, chain_index);
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if (n->nlmsg_type == RTM_NEWCHAIN) {
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@ -1866,23 +1909,27 @@ replay:
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tcf_chain_hold(chain);
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} else {
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NL_SET_ERR_MSG(extack, "Filter chain already exists");
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return -EEXIST;
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err = -EEXIST;
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goto errout_block;
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}
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} else {
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if (!(n->nlmsg_flags & NLM_F_CREATE)) {
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NL_SET_ERR_MSG(extack, "Need both RTM_NEWCHAIN and NLM_F_CREATE to create a new chain");
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return -ENOENT;
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err = -ENOENT;
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goto errout_block;
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}
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chain = tcf_chain_create(block, chain_index);
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if (!chain) {
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NL_SET_ERR_MSG(extack, "Failed to create filter chain");
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return -ENOMEM;
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err = -ENOMEM;
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goto errout_block;
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}
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}
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} else {
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if (!chain || tcf_chain_held_by_acts_only(chain)) {
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NL_SET_ERR_MSG(extack, "Cannot find specified filter chain");
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return -EINVAL;
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err = -EINVAL;
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goto errout_block;
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}
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tcf_chain_hold(chain);
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}
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@ -1926,6 +1973,8 @@ replay:
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errout:
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tcf_chain_put(chain);
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errout_block:
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tcf_block_release(q, block);
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if (err == -EAGAIN)
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/* Replay the request. */
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goto replay;
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