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Message-Id: <1544523120-4566-18-git-send-email-vladbu@mellanox.com>
Date: Tue, 11 Dec 2018 12:12:00 +0200
From: Vlad Buslov <vladbu@...lanox.com>
To: netdev@...r.kernel.org
Cc: jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
davem@...emloft.net, ast@...nel.org, daniel@...earbox.net,
Vlad Buslov <vladbu@...lanox.com>
Subject: [PATCH net-next v2 17/17] net: sched: unlock rules update API
Register netlink protocol handlers for message types RTM_NEWTFILTER,
RTM_DELTFILTER, RTM_GETTFILTER as unlocked. Set rtnl_held variable that
tracks rtnl mutex state to be false by default.
Introduce tcf_proto_is_unlocked() helper that is used to check
tcf_proto_ops->flag to determine if ops can be called without taking rtnl
lock. Manually lookup Qdisc, class and block in rule update handlers.
Verify that both Qdisc ops and proto ops are unlocked before using any of
their callbacks and obtain rtnl lock otherwise.
Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
---
Changes from V1 to V2:
- Refactor to only lock take rtnl lock once (at the beginning of rule
update handlers).
- Always release rtnl mutex in the same function that locked it.
Remove unlock code from tcf_block_release().
net/sched/cls_api.c | 142 ++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 120 insertions(+), 22 deletions(-)
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 0a841f65e518..33992cc1326f 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -180,6 +180,23 @@ static void tcf_proto_destroy_work(struct work_struct *work)
rtnl_unlock();
}
+static bool tcf_proto_is_unlocked(const char *kind)
+{
+ const struct tcf_proto_ops *ops;
+ bool ret;
+
+ ops = tcf_proto_lookup_ops(kind, false, NULL);
+ /* On error return false to take rtnl lock. Proto lookup/create
+ * functions will perform lookup again and properly handle errors.
+ */
+ if (IS_ERR(ops))
+ return false;
+
+ ret = !!(ops->flags & TCF_PROTO_OPS_DOIT_UNLOCKED);
+ module_put(ops->owner);
+ return ret;
+}
+
static struct tcf_proto *tcf_proto_create(const char *kind, u32 protocol,
u32 prio, struct tcf_chain *chain,
bool rtnl_held,
@@ -1310,13 +1327,18 @@ static struct tcf_block *tcf_block_find(struct net *net, struct Qdisc **q,
return ERR_PTR(err);
}
-static void tcf_block_release(struct Qdisc *q, struct tcf_block *block)
+static void tcf_block_release(struct Qdisc *q, struct tcf_block *block,
+ bool rtnl_held)
{
if (!IS_ERR_OR_NULL(block))
tcf_block_refcnt_put(block);
- if (q)
- qdisc_put(q);
+ if (q) {
+ if (rtnl_held)
+ qdisc_put(q);
+ else
+ qdisc_put_unlocked(q);
+ }
}
struct tcf_block_owner_item {
@@ -1992,7 +2014,7 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
void *fh;
int err;
int tp_created;
- bool rtnl_held = true;
+ bool rtnl_held = false;
if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
return -EPERM;
@@ -2011,6 +2033,7 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
parent = t->tcm_parent;
tp = NULL;
cl = 0;
+ block = NULL;
if (prio == 0) {
/* If no priority is provided by the user,
@@ -2027,8 +2050,27 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
/* Find head of filter chain. */
- block = tcf_block_find(net, &q, &parent, &cl,
- t->tcm_ifindex, t->tcm_block_index, extack);
+ err = __tcf_qdisc_find(net, &q, &parent, t->tcm_ifindex, false, extack);
+ if (err)
+ return err;
+
+ /* Take rtnl mutex if rtnl_held was set to true on previous iteration,
+ * block is shared (no qdisc found), qdisc is not unlocked, classifier
+ * type is not specified, classifier is not unlocked.
+ */
+ if (rtnl_held ||
+ (q && !(q->ops->cl_ops->flags & QDISC_CLASS_OPS_DOIT_UNLOCKED)) ||
+ !tca[TCA_KIND] || !tcf_proto_is_unlocked(nla_data(tca[TCA_KIND]))) {
+ rtnl_held = true;
+ rtnl_lock();
+ }
+
+ err = __tcf_qdisc_cl_find(q, parent, &cl, t->tcm_ifindex, extack);
+ if (err)
+ goto errout;
+
+ block = __tcf_block_find(net, q, cl, t->tcm_ifindex, t->tcm_block_index,
+ extack);
if (IS_ERR(block)) {
err = PTR_ERR(block);
goto errout;
@@ -2147,10 +2189,19 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
if (!tp_created)
tcf_chain_put(chain);
}
- tcf_block_release(q, block);
- if (err == -EAGAIN)
+ tcf_block_release(q, block, rtnl_held);
+
+ if (rtnl_held)
+ rtnl_unlock();
+
+ if (err == -EAGAIN) {
+ /* Take rtnl lock in case EAGAIN is caused by concurrent flush
+ * of target chain.
+ */
+ rtnl_held = true;
/* Replay the request. */
goto replay;
+ }
return err;
errout_locked:
@@ -2171,12 +2222,12 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
struct Qdisc *q = NULL;
struct tcf_chain_info chain_info;
struct tcf_chain *chain = NULL;
- struct tcf_block *block;
+ struct tcf_block *block = NULL;
struct tcf_proto *tp = NULL;
unsigned long cl = 0;
void *fh = NULL;
int err;
- bool rtnl_held = true;
+ bool rtnl_held = false;
if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
return -EPERM;
@@ -2197,8 +2248,27 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
/* Find head of filter chain. */
- block = tcf_block_find(net, &q, &parent, &cl,
- t->tcm_ifindex, t->tcm_block_index, extack);
+ err = __tcf_qdisc_find(net, &q, &parent, t->tcm_ifindex, false, extack);
+ if (err)
+ return err;
+
+ /* Take rtnl mutex if flushing whole chain, block is shared (no qdisc
+ * found), qdisc is not unlocked, classifier type is not specified,
+ * classifier is not unlocked.
+ */
+ if (!prio ||
+ (q && !(q->ops->cl_ops->flags & QDISC_CLASS_OPS_DOIT_UNLOCKED)) ||
+ !tca[TCA_KIND] || !tcf_proto_is_unlocked(nla_data(tca[TCA_KIND]))) {
+ rtnl_held = true;
+ rtnl_lock();
+ }
+
+ err = __tcf_qdisc_cl_find(q, parent, &cl, t->tcm_ifindex, extack);
+ if (err)
+ goto errout;
+
+ block = __tcf_block_find(net, q, cl, t->tcm_ifindex, t->tcm_block_index,
+ extack);
if (IS_ERR(block)) {
err = PTR_ERR(block);
goto errout;
@@ -2279,7 +2349,11 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
tcf_proto_put(tp, NULL);
tcf_chain_put(chain);
}
- tcf_block_release(q, block);
+ tcf_block_release(q, block, rtnl_held);
+
+ if (rtnl_held)
+ rtnl_unlock();
+
return err;
errout_locked:
@@ -2300,12 +2374,12 @@ static int tc_get_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
struct Qdisc *q = NULL;
struct tcf_chain_info chain_info;
struct tcf_chain *chain = NULL;
- struct tcf_block *block;
+ struct tcf_block *block = NULL;
struct tcf_proto *tp = NULL;
unsigned long cl = 0;
void *fh = NULL;
int err;
- bool rtnl_held = true;
+ bool rtnl_held = false;
err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, rtm_tca_policy, extack);
if (err < 0)
@@ -2323,8 +2397,26 @@ static int tc_get_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
/* Find head of filter chain. */
- block = tcf_block_find(net, &q, &parent, &cl,
- t->tcm_ifindex, t->tcm_block_index, extack);
+ err = __tcf_qdisc_find(net, &q, &parent, t->tcm_ifindex, false, extack);
+ if (err)
+ return err;
+
+ /* Take rtnl mutex if block is shared (no qdisc found), qdisc is not
+ * unlocked, classifier type is not specified, classifier is not
+ * unlocked.
+ */
+ if ((q && !(q->ops->cl_ops->flags & QDISC_CLASS_OPS_DOIT_UNLOCKED)) ||
+ !tca[TCA_KIND] || !tcf_proto_is_unlocked(nla_data(tca[TCA_KIND]))) {
+ rtnl_held = true;
+ rtnl_lock();
+ }
+
+ err = __tcf_qdisc_cl_find(q, parent, &cl, t->tcm_ifindex, extack);
+ if (err)
+ goto errout;
+
+ block = __tcf_block_find(net, q, cl, t->tcm_ifindex, t->tcm_block_index,
+ extack);
if (IS_ERR(block)) {
err = PTR_ERR(block);
goto errout;
@@ -2376,7 +2468,11 @@ static int tc_get_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
tcf_proto_put(tp, NULL);
tcf_chain_put(chain);
}
- tcf_block_release(q, block);
+ tcf_block_release(q, block, rtnl_held);
+
+ if (rtnl_held)
+ rtnl_unlock();
+
return err;
}
@@ -2823,7 +2919,7 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n,
errout:
tcf_chain_put(chain);
errout_block:
- tcf_block_release(q, block);
+ tcf_block_release(q, block, true);
if (err == -EAGAIN)
/* Replay the request. */
goto replay;
@@ -3166,10 +3262,12 @@ static int __init tc_filter_init(void)
if (err)
goto err_rhash_setup_block_ht;
- rtnl_register(PF_UNSPEC, RTM_NEWTFILTER, tc_new_tfilter, NULL, 0);
- rtnl_register(PF_UNSPEC, RTM_DELTFILTER, tc_del_tfilter, NULL, 0);
+ rtnl_register(PF_UNSPEC, RTM_NEWTFILTER, tc_new_tfilter, NULL,
+ RTNL_FLAG_DOIT_UNLOCKED);
+ rtnl_register(PF_UNSPEC, RTM_DELTFILTER, tc_del_tfilter, NULL,
+ RTNL_FLAG_DOIT_UNLOCKED);
rtnl_register(PF_UNSPEC, RTM_GETTFILTER, tc_get_tfilter,
- tc_dump_tfilter, 0);
+ tc_dump_tfilter, RTNL_FLAG_DOIT_UNLOCKED);
rtnl_register(PF_UNSPEC, RTM_NEWCHAIN, tc_ctl_chain, NULL, 0);
rtnl_register(PF_UNSPEC, RTM_DELCHAIN, tc_ctl_chain, NULL, 0);
rtnl_register(PF_UNSPEC, RTM_GETCHAIN, tc_ctl_chain,
--
2.7.5
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