net: sched: add helper function to take reference to Qdisc

Implement function to take reference to Qdisc that relies on rcu read lock
instead of rtnl mutex. Function only takes reference to Qdisc if reference
counter isn't zero. Intended to be used by unlocked cls API.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vlad Buslov 2018-09-24 19:22:52 +03:00 committed by David S. Miller
parent 3a7d0d07a3
commit 9d7e82cec3
1 changed files with 13 additions and 0 deletions

View File

@ -115,6 +115,19 @@ static inline void qdisc_refcount_inc(struct Qdisc *qdisc)
refcount_inc(&qdisc->refcnt);
}
/* Intended to be used by unlocked users, when concurrent qdisc release is
* possible.
*/
static inline struct Qdisc *qdisc_refcount_inc_nz(struct Qdisc *qdisc)
{
if (qdisc->flags & TCQ_F_BUILTIN)
return qdisc;
if (refcount_inc_not_zero(&qdisc->refcnt))
return qdisc;
return NULL;
}
static inline bool qdisc_is_running(struct Qdisc *qdisc)
{
if (qdisc->flags & TCQ_F_NOLOCK)