diff options
Diffstat (limited to 'include/net/sch_generic.h')
| -rw-r--r-- | include/net/sch_generic.h | 47 |
1 files changed, 19 insertions, 28 deletions
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 939fda8f9721..1ee396ce0eda 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -160,37 +160,17 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc) if (spin_trylock(&qdisc->seqlock)) goto nolock_empty; - /* Paired with smp_mb__after_atomic() to make sure - * STATE_MISSED checking is synchronized with clearing - * in pfifo_fast_dequeue(). + /* No need to insist if the MISSED flag was already set. + * Note that test_and_set_bit() also gives us memory ordering + * guarantees wrt potential earlier enqueue() and below + * spin_trylock(), both of which are necessary to prevent races */ - smp_mb__before_atomic(); - - /* If the MISSED flag is set, it means other thread has - * set the MISSED flag before second spin_trylock(), so - * we can return false here to avoid multi cpus doing - * the set_bit() and second spin_trylock() concurrently. - */ - if (test_bit(__QDISC_STATE_MISSED, &qdisc->state)) + if (test_and_set_bit(__QDISC_STATE_MISSED, &qdisc->state)) return false; - /* Set the MISSED flag before the second spin_trylock(), - * if the second spin_trylock() return false, it means - * other cpu holding the lock will do dequeuing for us - * or it will see the MISSED flag set after releasing - * lock and reschedule the net_tx_action() to do the - * dequeuing. - */ - set_bit(__QDISC_STATE_MISSED, &qdisc->state); - - /* spin_trylock() only has load-acquire semantic, so use - * smp_mb__after_atomic() to ensure STATE_MISSED is set - * before doing the second spin_trylock(). - */ - smp_mb__after_atomic(); - - /* Retry again in case other CPU may not see the new flag - * after it releases the lock at the end of qdisc_run_end(). + /* Try to take the lock again to make sure that we will either + * grab it or the CPU that still has it will see MISSED set + * when testing it in qdisc_run_end() */ if (!spin_trylock(&qdisc->seqlock)) return false; @@ -214,6 +194,12 @@ static inline void qdisc_run_end(struct Qdisc *qdisc) if (qdisc->flags & TCQ_F_NOLOCK) { spin_unlock(&qdisc->seqlock); + /* spin_unlock() only has store-release semantic. The unlock + * and test_bit() ordering is a store-load ordering, so a full + * memory barrier is needed here. + */ + smp_mb(); + if (unlikely(test_bit(__QDISC_STATE_MISSED, &qdisc->state))) { clear_bit(__QDISC_STATE_MISSED, &qdisc->state); @@ -1264,6 +1250,7 @@ struct psched_ratecfg { u64 rate_bytes_ps; /* bytes per second */ u32 mult; u16 overhead; + u16 mpu; u8 linklayer; u8 shift; }; @@ -1273,6 +1260,9 @@ static inline u64 psched_l2t_ns(const struct psched_ratecfg *r, { len += r->overhead; + if (len < r->mpu) + len = r->mpu; + if (unlikely(r->linklayer == TC_LINKLAYER_ATM)) return ((u64)(DIV_ROUND_UP(len,48)*53) * r->mult) >> r->shift; @@ -1295,6 +1285,7 @@ static inline void psched_ratecfg_getrate(struct tc_ratespec *res, res->rate = min_t(u64, r->rate_bytes_ps, ~0U); res->overhead = r->overhead; + res->mpu = r->mpu; res->linklayer = (r->linklayer & TC_LINKLAYER_MASK); } |