From dd25296afaf60b5140ddfa9e3d8e5d9df7076754 Mon Sep 17 00:00:00 2001 From: Yunsheng Lin Date: Tue, 22 Jun 2021 14:49:55 +0800 Subject: 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: Jakub Kicinski Tested-by: Vladimir Oltean # flexcan Signed-off-by: Yunsheng Lin Signed-off-by: David S. Miller --- include/net/sch_generic.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/net/sch_generic.h') diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 1e625519ae96..3ed6bcc4be72 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -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 @@ nolock_empty: 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); } } -- cgit v1.2.3-59-g8ed1b