From: Paolo Valente <paolo.valente@unimore.it>
Date: Tue, 5 Mar 2013 08:04:58 +0000 (+0000)
Subject: pkt_sched: sch_qfq: fix the update of eligible-group sets
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=624b85fb96206879c8146abdba071222bbd25259;p=linux-beck.git

pkt_sched: sch_qfq: fix the update of eligible-group sets

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index 489edd929932..39d85cc0db26 100644
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -821,7 +821,7 @@ 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);
 	}