Action API was changed to work with actions and action_idr in concurrency
safe manner, however tcf_del_walker() still uses actions without taking a
reference or idrinfo->lock first, and deletes them directly, disregarding
possible concurrent delete.
Add tc_action_wq workqueue to action API. Implement
tcf_idr_release_unsafe() that assumes external synchronization by caller
and delays blocking action cleanup part to tc_action_wq workqueue. Extend
tcf_action_cleanup() with 'async' argument to indicate that function should
free action asynchronously.
Change tcf_del_walker() to take idrinfo->lock while iterating over actions
and use new tcf_idr_release_unsafe() to release them while holding the
lock.
Signed-off-by: Vlad Buslov <vla...@mellanox.com>
---
include/net/act_api.h | 1 +
net/sched/act_api.c | 73 ++++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 65 insertions(+), 9 deletions(-)
diff --git a/include/net/act_api.h b/include/net/act_api.h
index c6f195b3c706..4c5117bc4afb 100644
--- a/include/net/act_api.h
+++ b/include/net/act_api.h
@@ -38,6 +38,7 @@ struct tc_action {
struct gnet_stats_queue __percpu *cpu_qstats;
struct tc_cookie __rcu *act_cookie;
struct tcf_chain *goto_chain;
+ struct work_struct work;
};
#define tcf_index common.tcfa_index
#define tcf_refcnt common.tcfa_refcnt
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 6f118d62c731..4ad9062c34b3 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -90,13 +90,38 @@ static void free_tcf(struct tc_action *p)
kfree(p);
}
-static void tcf_action_cleanup(struct tc_action *p)
+static void tcf_action_free(struct tc_action *p)
+{
+ gen_kill_estimator(&p->tcfa_rate_est);
+ free_tcf(p);
+}
+
+static void tcf_action_free_work(struct work_struct *work)
+{
+ struct tc_action *p = container_of(work,
+ struct tc_action,
+ work);
+
+ tcf_action_free(p);
+}
+
+static struct workqueue_struct *tc_action_wq;
+
+static bool tcf_action_queue_work(struct work_struct *work, work_func_t func)
+{
+ INIT_WORK(work, func);
+ return queue_work(tc_action_wq, work);
+}
+
+static void tcf_action_cleanup(struct tc_action *p, bool async)
{
if (p->ops->cleanup)
p->ops->cleanup(p);
- gen_kill_estimator(&p->tcfa_rate_est);
- free_tcf(p);
+ if (async)
+ tcf_action_queue_work(&p->work, tcf_action_free_work);
+ else
+ tcf_action_free(p);
}
static int __tcf_action_put(struct tc_action *p, bool bind)
@@ -109,7 +134,7 @@ static int __tcf_action_put(struct tc_action *p, bool bind)
idr_remove(&idrinfo->action_idr, p->tcfa_index);
spin_unlock(&idrinfo->lock);
- tcf_action_cleanup(p);
+ tcf_action_cleanup(p, false);
return 1;
}
@@ -147,6 +172,24 @@ int __tcf_idr_release(struct tc_action *p, bool bind, bool
strict)
}
EXPORT_SYMBOL(__tcf_idr_release);
+/* Release idr without obtaining idrinfo->lock. Caller must prevent any
+ * concurrent modifications of idrinfo->action_idr!
+ */
+
+static int tcf_idr_release_unsafe(struct tc_action *p)
+{
+ if (atomic_read(&p->tcfa_bindcnt) > 0)
+ return -EPERM;
+
+ if (refcount_dec_and_test(&p->tcfa_refcnt)) {
+ idr_remove(&p->idrinfo->action_idr, p->tcfa_index);
+ tcf_action_cleanup(p, true);
+ return ACT_P_DELETED;
+ }
+
+ return 0;
+}
+
static size_t tcf_action_shared_attrs_size(const struct tc_action *act)
{
struct tc_cookie *act_cookie;
@@ -262,20 +305,25 @@ static int tcf_del_walker(struct tcf_idrinfo *idrinfo,
struct sk_buff *skb,
if (nla_put_string(skb, TCA_KIND, ops->kind))
goto nla_put_failure;
+ spin_lock(&idrinfo->lock);
idr_for_each_entry_ul(idr, p, id) {
- ret = __tcf_idr_release(p, false, true);
+ ret = tcf_idr_release_unsafe(p);
if (ret == ACT_P_DELETED) {
module_put(ops->owner);
n_i++;
} else if (ret < 0) {
- goto nla_put_failure;
+ goto nla_put_failure_locked;
}
}
+ spin_unlock(&idrinfo->lock);
+
if (nla_put_u32(skb, TCA_FCNT, n_i))
goto nla_put_failure;
nla_nest_end(skb, nest);
return n_i;
+nla_put_failure_locked:
+ spin_unlock(&idrinfo->lock);
nla_put_failure:
nla_nest_cancel(skb, nest);
return ret;
@@ -341,7 +389,7 @@ static int tcf_idr_delete_index(struct tcf_idrinfo
*idrinfo, u32 index)
p->tcfa_index));
spin_unlock(&idrinfo->lock);
- tcf_action_cleanup(p);
+ tcf_action_cleanup(p, false);
module_put(owner);
return 0;
}
@@ -1713,16 +1761,23 @@ static int __init tc_action_init(void)
{
int err;
+ tc_action_wq = alloc_ordered_workqueue("tc_action_workqueue", 0);
+ if (!tc_action_wq)
+ return -ENOMEM;
+
err = register_pernet_subsys(&tcf_action_net_ops);
if (err)
- return err;
+ goto err_register_pernet_subsys;
rtnl_register(PF_UNSPEC, RTM_NEWACTION, tc_ctl_action, NULL, 0);
rtnl_register(PF_UNSPEC, RTM_DELACTION, tc_ctl_action, NULL, 0);
rtnl_register(PF_UNSPEC, RTM_GETACTION, tc_ctl_action, tc_dump_action,
0);
+ return err;
- return 0;
+err_register_pernet_subsys:
+ destroy_workqueue(tc_action_wq);
+ return err;
}
subsys_initcall(tc_action_init);
--
2.7.5
