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net_sched: transform qdisc running bit into a seqcount

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Instead of using a single bit (__QDISC___STATE_RUNNING)
in sch->__state, use a seqcount.

This adds lockdep support, but more importantly it will allow us
to sample qdisc/class statistics without having to grab qdisc root lock.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2016-06-06 09:37:15 -07:00
committed by David S. Miller
parent 64151ae36e
commit f9eb8aea2a
10 changed files with 32 additions and 16 deletions
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15
include/net/sch_generic.h
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@@ -29,13 +29,6 @@ enum qdisc_state_t {
__QDISC_STATE_THROTTLED,
};
/*
* following bits are only changed while qdisc lock is held
*/
enum qdisc___state_t {
__QDISC___STATE_RUNNING = 1,
};
struct qdisc_size_table {
struct rcu_head rcu;
struct list_head list;
@@ -93,7 +86,7 @@ struct Qdisc {
unsigned long state;
struct sk_buff_head q;
struct gnet_stats_basic_packed bstats;
unsigned int __state;
seqcount_t running;
struct gnet_stats_queue qstats;
struct rcu_head rcu_head;
int padded;
@@ -104,20 +97,20 @@ struct Qdisc {
static inline bool qdisc_is_running(const struct Qdisc *qdisc)
{
return (qdisc->__state & __QDISC___STATE_RUNNING) ? true : false;
return (raw_read_seqcount(&qdisc->running) & 1) ? true : false;
}
static inline bool qdisc_run_begin(struct Qdisc *qdisc)
{
if (qdisc_is_running(qdisc))
return false;
qdisc->__state |= __QDISC___STATE_RUNNING;
write_seqcount_begin(&qdisc->running);
return true;
}
static inline void qdisc_run_end(struct Qdisc *qdisc)
{
qdisc->__state &= ~__QDISC___STATE_RUNNING;
write_seqcount_end(&qdisc->running);
}
static inline bool qdisc_may_bulk(const struct Qdisc *qdisc)