Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 24/84] pkt_sched: fix virtual-start-time update in QFQ | Date | Thu, 11 Oct 2012 11:03:08 +0900 |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: Paolo Valente <paolo.valente@unimore.it>
[ 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> --- net/sched/sch_qfq.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -829,7 +829,10 @@ static void qfq_update_start(struct qfq_ 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; } }
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