From d3e0f57501bde8a9585aff79afcffd99e6a5d91c Mon Sep 17 00:00:00 2001 From: Yunsheng Lin Date: Tue, 22 Jun 2021 14:49:57 +0800 Subject: [PATCH] net: sched: remove qdisc->empty for lockless qdisc As MISSED and DRAINING state are used to indicate a non-empty qdisc, qdisc->empty is not longer needed, so remove it. 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 | 13 +++---------- net/sched/sch_generic.c | 3 --- 2 files changed, 3 insertions(+), 13 deletions(-) diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 177f240d59d4..c99ffe9cc88f 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -117,8 +117,6 @@ struct Qdisc { spinlock_t busylock ____cacheline_aligned_in_smp; spinlock_t seqlock; - /* for NOLOCK qdisc, true if there are no enqueued skbs */ - bool empty; struct rcu_head rcu; /* private data */ @@ -165,7 +163,7 @@ static inline bool qdisc_is_percpu_stats(const struct Qdisc *q) static inline bool qdisc_is_empty(const struct Qdisc *qdisc) { if (qdisc_is_percpu_stats(qdisc)) - return READ_ONCE(qdisc->empty); + return nolock_qdisc_is_empty(qdisc); return !READ_ONCE(qdisc->q.qlen); } @@ -173,7 +171,7 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc) { if (qdisc->flags & TCQ_F_NOLOCK) { if (spin_trylock(&qdisc->seqlock)) - goto nolock_empty; + return true; /* If the MISSED flag is set, it means other thread has * set the MISSED flag before second spin_trylock(), so @@ -195,12 +193,7 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc) /* Retry again in case other CPU may not see the new flag * after it releases the lock at the end of qdisc_run_end(). */ - if (!spin_trylock(&qdisc->seqlock)) - return false; - -nolock_empty: - WRITE_ONCE(qdisc->empty, false); - return true; + return spin_trylock(&qdisc->seqlock); } else if (qdisc_is_running(qdisc)) { return false; } diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 9984ccc45946..d9ac60ffe927 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -725,8 +725,6 @@ retry: need_retry = false; goto retry; - } else { - WRITE_ONCE(qdisc->empty, true); } return skb; @@ -927,7 +925,6 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue, sch->enqueue = ops->enqueue; sch->dequeue = ops->dequeue; sch->dev_queue = dev_queue; - sch->empty = true; dev_hold(dev); refcount_set(&sch->refcnt, 1); -- 2.11.0