| Message ID | 20120915104134.GA29862@paolo-ThinkPad-W520 |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Paolo Valente <paolo.valente@unimore.it> Date: Sat, 15 Sep 2012 12:41:35 +0200 > If the old timestamps of a class, say cl, are stale when the class > becomes active, then QFQ may assign to cl a much higher start time > than the maximum value allowed. This may happen when QFQ assigns to > the start time of cl the finish time of a group whose classes are > characterized by a higher value of the ratio > max_class_pkt/weight_of_the_class with respect to that of > cl. Inserting a class with a too high start time into the bucket list > corrupts the data structure and may eventually lead to crashes. > This patch limits the maximum start time assigned to a class. > > Signed-off-by: Paolo Valente <paolo.valente@unimore.it> Applied and queued up for -stable, thanks. Please use "pkt_sched" instead of just plain "sched" in the prefixes of your subject lines for packet scheduler changes so such changes can be distinguished from process scheduler changes. I fixed it up for you this time. Thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index e4723d3..211a212 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -865,7 +865,10 @@ static void qfq_update_start(struct qfq_sched *q, struct qfq_class *cl) if (mask) { struct qfq_group *next = qfq_ffs(q, mask); if (qfq_gt(roundedF, next->F)) { - cl->S = next->F; + if (qfq_gt(limit, next->F)) + cl->S = next->F; + else /* preserve timestamp correctness */ + cl->S = limit; return; } }
If the old timestamps of a class, say cl, are stale when the class becomes active, then QFQ may assign to cl a much higher start time than the maximum value allowed. This may happen when QFQ assigns to the start time of cl the finish time of a group whose classes are characterized by a higher value of the ratio max_class_pkt/weight_of_the_class with respect to that of cl. Inserting a class with a too high start time into the bucket list corrupts the data structure and may eventually lead to crashes. This patch limits the maximum start time assigned to a class. Signed-off-by: Paolo Valente <paolo.valente@unimore.it> --- net/sched/sch_qfq.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)