Commit dd25296a authored by Yunsheng Lin's avatar Yunsheng Lin Committed by David S. Miller
Browse files

net: sched: avoid unnecessary seqcount operation for lockless qdisc 



qdisc->running seqcount operation is mainly used to do heuristic
locking on q->busylock for locked qdisc, see qdisc_is_running()
and __dev_xmit_skb().

So avoid doing seqcount operation for qdisc with TCQ_F_NOLOCK
flag.

Acked-by: default avatarJakub Kicinski <kuba@kernel.org>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com> # flexcan
Signed-off-by: default avatarYunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 38f75922

include/net/sch_generic.h

+3 −1
Original line number Diff line number Diff line
@@ -188,6 +188,7 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc) 


nolock_empty:

		WRITE_ONCE(qdisc->empty, false);

		return true;

	} else if (qdisc_is_running(qdisc)) {

		return false;

	}
@@ -201,7 +202,6 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc) 


static inline void qdisc_run_end(struct Qdisc *qdisc)

{

	write_seqcount_end(&qdisc->running);

	if (qdisc->flags & TCQ_F_NOLOCK) {

		spin_unlock(&qdisc->seqlock);
@@ -210,6 +210,8 @@ static inline void qdisc_run_end(struct Qdisc *qdisc) 
			clear_bit(__QDISC_STATE_MISSED, &qdisc->state);

			__netif_schedule(qdisc);

		}

	} else {

		write_seqcount_end(&qdisc->running);

	}

}