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authorPaolo Valente <paolo.valente@unimore.it>2012-09-15 00:41:35 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-10-13 05:28:06 +0900
commit3f99feef88eb867056bd4459e4cf68da33af8861 (patch)
tree5fae9878c0d2732aad01e3bfd660721f3e7163d3 /net
parent829f2161f7057a511df7a41e52c5a43cbf5a49d7 (diff)
pkt_sched: fix virtual-start-time update in QFQ
[ Upstream commit 71261956973ba9e0637848a5adb4a5819b4bae83 ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-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 103343408593..f86bc727b98f 100644
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -829,7 +829,10 @@ 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;
}
}