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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-03-24 00:13:14 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-03-24 00:13:14 -0700 |
| commit | ef352e7cdf714596f51ad18809404edeaa50e8fd (patch) | |
| tree | 6323cffca24cba664cd57a7245eb78647c48b914 | |
| parent | 8c64b4cc0201cf05b218ea3271a2abb4f86acb7b (diff) | |
| download | linux-ef352e7cdf714596f51ad18809404edeaa50e8fd.tar.gz linux-ef352e7cdf714596f51ad18809404edeaa50e8fd.tar.bz2 linux-ef352e7cdf714596f51ad18809404edeaa50e8fd.zip | |
net_sched: fix THROTTLED/RUNNING race
commit fd245a4adb52 (net_sched: move TCQ_F_THROTTLED flag)
added a race.
qdisc_watchdog() is run from softirq, so special care should be taken or
we can lose one state transition (THROTTLED/RUNNING)
Prior to fd245a4adb52, we were manipulating q->flags (qdisc->flags &=
~TCQ_F_THROTTLED;) and this manipulation could only race with
qdisc_warn_nonwc().
Since we want to avoid atomic ops in qdisc fast path - it was the
meaning of commit 371121057607e (QDISC_STATE_RUNNING dont need atomic
bit ops) - fix is to move THROTTLE bit into 'state' field, this one
being manipulated with SMP and IRQ safe operations.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/sch_generic.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index a9505b6a18e3..b931f021d7ab 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -25,6 +25,7 @@ struct qdisc_rate_table { enum qdisc_state_t { __QDISC_STATE_SCHED, __QDISC_STATE_DEACTIVATED, + __QDISC_STATE_THROTTLED, }; /* @@ -32,7 +33,6 @@ enum qdisc_state_t { */ enum qdisc___state_t { __QDISC___STATE_RUNNING = 1, - __QDISC___STATE_THROTTLED = 2, }; struct qdisc_size_table { @@ -106,17 +106,17 @@ static inline void qdisc_run_end(struct Qdisc *qdisc) static inline bool qdisc_is_throttled(const struct Qdisc *qdisc) { - return (qdisc->__state & __QDISC___STATE_THROTTLED) ? true : false; + return test_bit(__QDISC_STATE_THROTTLED, &qdisc->state) ? true : false; } static inline void qdisc_throttled(struct Qdisc *qdisc) { - qdisc->__state |= __QDISC___STATE_THROTTLED; + set_bit(__QDISC_STATE_THROTTLED, &qdisc->state); } static inline void qdisc_unthrottled(struct Qdisc *qdisc) { - qdisc->__state &= ~__QDISC___STATE_THROTTLED; + clear_bit(__QDISC_STATE_THROTTLED, &qdisc->state); } struct Qdisc_class_ops { |