In order to remove dependency on rtnl lock on rules update path, always
take reference to block while using it on rules update path. Change
tcf_block_get() error handling to properly release block with reference
counting, instead of just destroying it, in order to accommodate potential
concurrent users.
Signed-off-by: Vlad Buslov <vla...@mellanox.com>
Acked-by: Jiri Pirko <j...@mellanox.com>
---
net/sched/cls_api.c | 37 ++++++++++++++++++++-----------------
1 file changed, 20 insertions(+), 17 deletions(-)
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 0a7a3ace2da9..6a3eec5dbdf1 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -633,7 +633,7 @@ static struct tcf_block *tcf_block_find(struct net *net,
struct Qdisc **q,
int err = 0;
if (ifindex == TCM_IFINDEX_MAGIC_BLOCK) {
- block = tcf_block_lookup(net, block_index);
+ block = tcf_block_refcnt_get(net, block_index);
if (!block) {
NL_SET_ERR_MSG(extack, "Block of given index was not
found");
return ERR_PTR(-EINVAL);
@@ -713,6 +713,14 @@ static struct tcf_block *tcf_block_find(struct net *net,
struct Qdisc **q,
err = -EOPNOTSUPP;
goto errout_qdisc;
}
+
+ /* Always take reference to block in order to support execution
+ * of rules update path of cls API without rtnl lock. Caller
+ * must release block when it is finished using it. 'if' block
+ * of this conditional obtain reference to block by calling
+ * tcf_block_refcnt_get().
+ */
+ refcount_inc(&block->refcnt);
}
return block;
@@ -726,6 +734,8 @@ static struct tcf_block *tcf_block_find(struct net *net,
struct Qdisc **q,
static void tcf_block_release(struct Qdisc *q, struct tcf_block *block)
{
+ if (!IS_ERR_OR_NULL(block))
+ tcf_block_refcnt_put(block);
tcf_qdisc_put(q, true);
}
@@ -794,21 +804,16 @@ int tcf_block_get_ext(struct tcf_block **p_block, struct
Qdisc *q,
{
struct net *net = qdisc_net(q);
struct tcf_block *block = NULL;
- bool created = false;
int err;
- if (ei->block_index) {
+ if (ei->block_index)
/* block_index not 0 means the shared block is requested */
- block = tcf_block_lookup(net, ei->block_index);
- if (block)
- refcount_inc(&block->refcnt);
- }
+ block = tcf_block_refcnt_get(net, ei->block_index);
if (!block) {
block = tcf_block_create(net, q, ei->block_index, extack);
if (IS_ERR(block))
return PTR_ERR(block);
- created = true;
if (tcf_block_shared(block)) {
err = tcf_block_insert(block, net, extack);
if (err)
@@ -838,14 +843,8 @@ int tcf_block_get_ext(struct tcf_block **p_block, struct
Qdisc *q,
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_rcu(block, rcu);
- } else {
- refcount_dec(&block->refcnt);
- }
+ tcf_block_refcnt_put(block);
return err;
}
EXPORT_SYMBOL(tcf_block_get_ext);
@@ -1739,7 +1738,7 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct
netlink_callback *cb)
return err;
if (tcm->tcm_ifindex == TCM_IFINDEX_MAGIC_BLOCK) {
- block = tcf_block_lookup(net, tcm->tcm_block_index);
+ block = tcf_block_refcnt_get(net, tcm->tcm_block_index);
if (!block)
goto out;
/* If we work with block index, q is NULL and parent value
@@ -1798,6 +1797,8 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct
netlink_callback *cb)
}
}
+ if (tcm->tcm_ifindex == TCM_IFINDEX_MAGIC_BLOCK)
+ tcf_block_refcnt_put(block);
cb->args[0] = index;
out:
@@ -2062,7 +2063,7 @@ static int tc_dump_chain(struct sk_buff *skb, struct
netlink_callback *cb)
return err;
if (tcm->tcm_ifindex == TCM_IFINDEX_MAGIC_BLOCK) {
- block = tcf_block_lookup(net, tcm->tcm_block_index);
+ block = tcf_block_refcnt_get(net, tcm->tcm_block_index);
if (!block)
goto out;
/* If we work with block index, q is NULL and parent value
@@ -2129,6 +2130,8 @@ static int tc_dump_chain(struct sk_buff *skb, struct
netlink_callback *cb)
index++;
}
+ if (tcm->tcm_ifindex == TCM_IFINDEX_MAGIC_BLOCK)
+ tcf_block_refcnt_put(block);
cb->args[0] = index;
out:
--
2.7.5
