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Subject[PATCH BUGFIX 2/6] pkt_sched: fix the update of eligible-group sets
Date
Between two invocations of make_eligible, the system virtual time may
happen to grow enough that, in its binary representation, a bit with
higher order than 31 flips. This happens especially with
TSO/GSO. Before this fix, the mask used in make_eligible was computed
as (1UL<<index_of_last_flipped_bit)-1, whose value is well defined on
a 64-bit architecture, because index_of_flipped_bit <= 63, but is in
general undefined on a 32-bit architecture if index_of_flipped_bit > 31.
The fix just replaces 1UL with 1ULL.

Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Reviewed-by: Fabio Checconi <fchecconi@gmail.com>
---
net/sched/sch_qfq.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index 0f6e2db..4cbbf79 100644
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -823,7 +823,7 @@ static void qfq_make_eligible(struct qfq_sched *q)
unsigned long old_vslot = q->oldV >> q->min_slot_shift;

if (vslot != old_vslot) {
- unsigned long mask = (1UL << fls(vslot ^ old_vslot)) - 1;
+ unsigned long mask = (1ULL << fls(vslot ^ old_vslot)) - 1;
qfq_move_groups(q, mask, IR, ER);
qfq_move_groups(q, mask, IB, EB);
}
--
1.7.9.5


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