net: sched: Avoid implicit chain 0 creation

Currently, chain 0 is implicitly created during block creation. However
that does not align with chain object exposure, creation and destruction
api introduced later on. So make the chain 0 behave the same way as any
other chain and only create it when it is needed. Since chain 0 is
somehow special as the qdiscs need to hold pointer to the first chain
tp, this requires to move the chain head change callback infra to the
block structure.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 7432100027b7f14d4bbd4109901bd8b144a39415..86f4651784e88454e55316eace227bed558147fe 100644 (file)
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -300,7 +300,6 @@ typedef void tcf_chain_head_change_t(struct tcf_proto *tp_head, void *priv);
 
 struct tcf_chain {
        struct tcf_proto __rcu *filter_chain;
-       struct list_head filter_chain_list;
        struct list_head list;
        struct tcf_block *block;
        u32 index; /* chain index */
@@ -318,6 +317,10 @@ struct tcf_block {
        bool keep_dst;
        unsigned int offloadcnt; /* Number of oddloaded filters */
        unsigned int nooffloaddevcnt; /* Number of devs unable to do offload */
+       struct {
+               struct tcf_chain *chain;
+               struct list_head filter_chain_list;
+       } chain0;
 };
 
 static inline void tcf_block_offload_inc(struct tcf_block *block, u32 *flags)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 1e8d69790d820f1ed56459ae20bf850e2e14ac29..eb0bf9037ef956054c78903ec02a915eaaf5a788 100644 (file)
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -204,11 +204,12 @@ static struct tcf_chain *tcf_chain_create(struct tcf_block *block,
        chain = kzalloc(sizeof(*chain), GFP_KERNEL);
        if (!chain)
                return NULL;
-       INIT_LIST_HEAD(&chain->filter_chain_list);
        list_add_tail(&chain->list, &block->chain_list);
        chain->block = block;
        chain->index = chain_index;
        chain->refcnt = 1;
+       if (!chain->index)
+               block->chain0.chain = chain;
        return chain;
 }
 
@@ -218,12 +219,16 @@ static void tcf_chain_head_change_item(struct tcf_filter_chain_list_item *item,
        if (item->chain_head_change)
                item->chain_head_change(tp_head, item->chain_head_change_priv);
 }
-static void tcf_chain_head_change(struct tcf_chain *chain,
-                                 struct tcf_proto *tp_head)
+
+static void tcf_chain0_head_change(struct tcf_chain *chain,
+                                  struct tcf_proto *tp_head)
 {
        struct tcf_filter_chain_list_item *item;
+       struct tcf_block *block = chain->block;
 
-       list_for_each_entry(item, &chain->filter_chain_list, list)
+       if (chain->index)
+               return;
+       list_for_each_entry(item, &block->chain0.filter_chain_list, list)
                tcf_chain_head_change_item(item, tp_head);
 }
 
@@ -231,7 +236,7 @@ static void tcf_chain_flush(struct tcf_chain *chain)
 {
        struct tcf_proto *tp = rtnl_dereference(chain->filter_chain);
 
-       tcf_chain_head_change(chain, NULL);
+       tcf_chain0_head_change(chain, NULL);
        while (tp) {
                RCU_INIT_POINTER(chain->filter_chain, tp->next);
                tcf_proto_destroy(tp, NULL);
@@ -245,8 +250,10 @@ static void tcf_chain_destroy(struct tcf_chain *chain)
        struct tcf_block *block = chain->block;
 
        list_del(&chain->list);
+       if (!chain->index)
+               block->chain0.chain = NULL;
        kfree(chain);
-       if (list_empty(&block->chain_list))
+       if (list_empty(&block->chain_list) && block->refcnt == 0)
                kfree(block);
 }
 
@@ -346,10 +353,11 @@ no_offload_dev_dec:
 }
 
 static int
-tcf_chain_head_change_cb_add(struct tcf_chain *chain,
-                            struct tcf_block_ext_info *ei,
-                            struct netlink_ext_ack *extack)
+tcf_chain0_head_change_cb_add(struct tcf_block *block,
+                             struct tcf_block_ext_info *ei,
+                             struct netlink_ext_ack *extack)
 {
+       struct tcf_chain *chain0 = block->chain0.chain;
        struct tcf_filter_chain_list_item *item;
 
        item = kmalloc(sizeof(*item), GFP_KERNEL);
@@ -359,23 +367,25 @@ tcf_chain_head_change_cb_add(struct tcf_chain *chain,
        }
        item->chain_head_change = ei->chain_head_change;
        item->chain_head_change_priv = ei->chain_head_change_priv;
-       if (chain->filter_chain)
-               tcf_chain_head_change_item(item, chain->filter_chain);
-       list_add(&item->list, &chain->filter_chain_list);
+       if (chain0 && chain0->filter_chain)
+               tcf_chain_head_change_item(item, chain0->filter_chain);
+       list_add(&item->list, &block->chain0.filter_chain_list);
        return 0;
 }
 
 static void
-tcf_chain_head_change_cb_del(struct tcf_chain *chain,
-                            struct tcf_block_ext_info *ei)
+tcf_chain0_head_change_cb_del(struct tcf_block *block,
+                             struct tcf_block_ext_info *ei)
 {
+       struct tcf_chain *chain0 = block->chain0.chain;
        struct tcf_filter_chain_list_item *item;
 
-       list_for_each_entry(item, &chain->filter_chain_list, list) {
+       list_for_each_entry(item, &block->chain0.filter_chain_list, list) {
                if ((!ei->chain_head_change && !ei->chain_head_change_priv) ||
                    (item->chain_head_change == ei->chain_head_change &&
                     item->chain_head_change_priv == ei->chain_head_change_priv)) {
-                       tcf_chain_head_change_item(item, NULL);
+                       if (chain0)
+                               tcf_chain_head_change_item(item, NULL);
                        list_del(&item->list);
                        kfree(item);
                        return;
@@ -411,8 +421,6 @@ static struct tcf_block *tcf_block_create(struct net *net, struct Qdisc *q,
                                          struct netlink_ext_ack *extack)
 {
        struct tcf_block *block;
-       struct tcf_chain *chain;
-       int err;
 
        block = kzalloc(sizeof(*block), GFP_KERNEL);
        if (!block) {
@@ -422,14 +430,8 @@ static struct tcf_block *tcf_block_create(struct net *net, struct Qdisc *q,
        INIT_LIST_HEAD(&block->chain_list);
        INIT_LIST_HEAD(&block->cb_list);
        INIT_LIST_HEAD(&block->owner_list);
+       INIT_LIST_HEAD(&block->chain0.filter_chain_list);
 
-       /* Create chain 0 by default, it has to be always present. */
-       chain = tcf_chain_create(block, 0);
-       if (!chain) {
-               NL_SET_ERR_MSG(extack, "Failed to create new tcf chain");
-               err = -ENOMEM;
-               goto err_chain_create;
-       }
        block->refcnt = 1;
        block->net = net;
        block->index = block_index;
@@ -438,10 +440,6 @@ static struct tcf_block *tcf_block_create(struct net *net, struct Qdisc *q,
        if (!tcf_block_shared(block))
                block->q = q;
        return block;
-
-err_chain_create:
-       kfree(block);
-       return ERR_PTR(err);
 }
 
 static struct tcf_block *tcf_block_lookup(struct net *net, u32 block_index)
@@ -523,11 +521,6 @@ static struct tcf_block *tcf_block_find(struct net *net, struct Qdisc **q,
        return block;
 }
 
-static struct tcf_chain *tcf_block_chain_zero(struct tcf_block *block)
-{
-       return list_first_entry(&block->chain_list, struct tcf_chain, list);
-}
-
 struct tcf_block_owner_item {
        struct list_head list;
        struct Qdisc *q;
@@ -621,10 +614,9 @@ int tcf_block_get_ext(struct tcf_block **p_block, struct Qdisc *q,
 
        tcf_block_owner_netif_keep_dst(block, q, ei->binder_type);
 
-       err = tcf_chain_head_change_cb_add(tcf_block_chain_zero(block),
-                                          ei, extack);
+       err = tcf_chain0_head_change_cb_add(block, ei, extack);
        if (err)
-               goto err_chain_head_change_cb_add;
+               goto err_chain0_head_change_cb_add;
 
        err = tcf_block_offload_bind(block, q, ei, extack);
        if (err)
@@ -634,15 +626,14 @@ int tcf_block_get_ext(struct tcf_block **p_block, struct Qdisc *q,
        return 0;
 
 err_block_offload_bind:
-       tcf_chain_head_change_cb_del(tcf_block_chain_zero(block), ei);
-err_chain_head_change_cb_add:
+       tcf_chain0_head_change_cb_del(block, ei);
+err_chain0_head_change_cb_add:
        tcf_block_owner_del(block, q, ei->binder_type);
 err_block_owner_add:
        if (created) {
                if (tcf_block_shared(block))
                        tcf_block_remove(block, net);
 err_block_insert:
-               kfree(tcf_block_chain_zero(block));
                kfree(block);
        } else {
                block->refcnt--;
@@ -682,10 +673,10 @@ void tcf_block_put_ext(struct tcf_block *block, struct Qdisc *q,
 
        if (!block)
                return;
-       tcf_chain_head_change_cb_del(tcf_block_chain_zero(block), ei);
+       tcf_chain0_head_change_cb_del(block, ei);
        tcf_block_owner_del(block, q, ei->binder_type);
 
-       if (--block->refcnt == 0) {
+       if (block->refcnt == 1) {
                if (tcf_block_shared(block))
                        tcf_block_remove(block, block->net);
 
@@ -701,13 +692,14 @@ void tcf_block_put_ext(struct tcf_block *block, struct Qdisc *q,
 
        tcf_block_offload_unbind(block, q, ei);
 
-       if (block->refcnt == 0) {
+       if (block->refcnt == 1) {
                /* At this point, all the chains should have refcnt >= 1. */
                list_for_each_entry_safe(chain, tmp, &block->chain_list, list)
                        tcf_chain_put(chain);
 
-               /* Finally, put chain 0 and allow block to be freed. */
-               tcf_chain_put(tcf_block_chain_zero(block));
+               block->refcnt--;
+               if (list_empty(&block->chain_list))
+                       kfree(block);
        }
 }
 EXPORT_SYMBOL(tcf_block_put_ext);
@@ -947,7 +939,7 @@ static void tcf_chain_tp_insert(struct tcf_chain *chain,
                                struct tcf_proto *tp)
 {
        if (*chain_info->pprev == chain->filter_chain)
-               tcf_chain_head_change(chain, tp);
+               tcf_chain0_head_change(chain, tp);
        RCU_INIT_POINTER(tp->next, tcf_chain_tp_prev(chain_info));
        rcu_assign_pointer(*chain_info->pprev, tp);
        tcf_chain_hold(chain);
@@ -960,7 +952,7 @@ static void tcf_chain_tp_remove(struct tcf_chain *chain,
        struct tcf_proto *next = rtnl_dereference(chain_info->next);
 
        if (tp == chain->filter_chain)
-               tcf_chain_head_change(chain, next);
+               tcf_chain0_head_change(chain, next);
        RCU_INIT_POINTER(*chain_info->pprev, next);
        tcf_chain_put(chain);
 }