Commit 97604c65 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

net: sched: remove one pair of atomic operations 



__QDISC_STATE_RUNNING is only set/cleared from contexts owning qdisc lock.

Thus we can use less expensive bit operations, as we were doing
before commit f9eb8aea ("net_sched: transform qdisc running bit into a seqcount")

Fixes: 29cbcd85 ("net: sched: Remove Qdisc::running sequence counter")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Ahmed S. Darwish <a.darwish@linutronix.de>
Acked-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 4c57e2fa

include/net/sch_generic.h

+8 −4
Original line number Diff line number Diff line
@@ -38,10 +38,13 @@ enum qdisc_state_t { 
	__QDISC_STATE_DEACTIVATED,

	__QDISC_STATE_MISSED,

	__QDISC_STATE_DRAINING,

};



enum qdisc_state2_t {

	/* Only for !TCQ_F_NOLOCK qdisc. Never access it directly.

	 * Use qdisc_run_begin/end() or qdisc_is_running() instead.

	 */

	__QDISC_STATE_RUNNING,

	__QDISC_STATE2_RUNNING,

};



#define QDISC_STATE_MISSED	BIT(__QDISC_STATE_MISSED)
@@ -114,6 +117,7 @@ struct Qdisc { 
	struct gnet_stats_basic_sync bstats;

	struct gnet_stats_queue	qstats;

	unsigned long		state;

	unsigned long		state2; /* must be written under qdisc spinlock */

	struct Qdisc            *next_sched;

	struct sk_buff_head	skb_bad_txq;
@@ -154,7 +158,7 @@ static inline bool qdisc_is_running(struct Qdisc *qdisc) 
{

	if (qdisc->flags & TCQ_F_NOLOCK)

		return spin_is_locked(&qdisc->seqlock);

	return test_bit(__QDISC_STATE_RUNNING, &qdisc->state);

	return test_bit(__QDISC_STATE2_RUNNING, &qdisc->state2);

}



static inline bool nolock_qdisc_is_empty(const struct Qdisc *qdisc)
@@ -217,7 +221,7 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc) 
		 */

		return spin_trylock(&qdisc->seqlock);

	}

	return !test_and_set_bit(__QDISC_STATE_RUNNING, &qdisc->state);

	return !__test_and_set_bit(__QDISC_STATE2_RUNNING, &qdisc->state2);

}



static inline void qdisc_run_end(struct Qdisc *qdisc)
@@ -229,7 +233,7 @@ static inline void qdisc_run_end(struct Qdisc *qdisc) 
				      &qdisc->state)))

			__netif_schedule(qdisc);

	} else {

		clear_bit(__QDISC_STATE_RUNNING, &qdisc->state);

		__clear_bit(__QDISC_STATE2_RUNNING, &qdisc->state2);

	}

}