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authorPaolo Valente <paolo.valente@unimore.it>2012-09-15 04:41:35 +0400
committerDavid S. Miller <davem@davemloft.net>2012-09-20 00:23:53 +0400
commit71261956973ba9e0637848a5adb4a5819b4bae83 (patch)
treeb73da61b6f4ff0c5156f6f1a2252ed98304366a3 /net/sched/sch_qfq.c
parent15c041759bfcd9ab0a4e43f1c16e2644977d0467 (diff)
downloadlinux-71261956973ba9e0637848a5adb4a5819b4bae83.tar.xz
pkt_sched: fix virtual-start-time update in QFQ
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> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/sch_qfq.c')
-rw-r--r--net/sched/sch_qfq.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index e4723d31fdd5..211a21217045 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;
}
}