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net: sched: avoid unnecessary seqcount operation for lockless qdisc

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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 <kuba@kernel.org>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com> # flexcan
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yunsheng Lin 2021-06-22 14:49:55 +08:00 committed by David S. Miller
parent 38f75922a6
commit dd25296afa
1 changed files with 3 additions and 1 deletions
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4
include/net/sch_generic.h
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@ -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);
}
}