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sch_qfq: fix overflow in qfq_update_start()

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grp->slot_shift is between 22 and 41, so using 32bit wide variables is
probably a typo.

This could explain QFQ hangs Dave reported to me, after 2^23 packets ?

(23 = 64 - 41)

Reported-by: Dave Taht <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
CC: Stephen Hemminger <[email protected]>
CC: Dave Taht <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Eric Dumazet 2012-01-02 05:47:57 +00:00 • committed by David S. Miller
commit 6bafcac323
1 changed files with 2 additions and 2 deletions
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4
net/sched/sch_qfq.c
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@ -817,11 +817,11 @@ skip_unblock:
static void qfq_update_start(struct qfq_sched *q, struct qfq_class *cl)
{
unsigned long mask;
uint32_t limit, roundedF;
u64 limit, roundedF;
int slot_shift = cl->grp->slot_shift;
roundedF = qfq_round_down(cl->F, slot_shift);
limit = qfq_round_down(q->V, slot_shift) + (1UL << slot_shift);
limit = qfq_round_down(q->V, slot_shift) + (1ULL << slot_shift);
if (!qfq_gt(cl->F, q->V) || qfq_gt(roundedF, limit)) {
/* timestamp was stale */