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| author | Paolo Valente <paolo.valente@unimore.it> | 2012-09-15 00:41:35 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-10-13 05:28:06 +0900 |
| commit | 3f99feef88eb867056bd4459e4cf68da33af8861 (patch) | |
| tree | 5fae9878c0d2732aad01e3bfd660721f3e7163d3 | |
| parent | 829f2161f7057a511df7a41e52c5a43cbf5a49d7 (diff) | |
| download | lwn-3f99feef88eb867056bd4459e4cf68da33af8861.tar.gz lwn-3f99feef88eb867056bd4459e4cf68da33af8861.zip | |
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>
| -rw-r--r-- | net/sched/sch_qfq.c | 5 |
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; } } |