lwn.git/net/sched, branch v3.11-rc6

net_sched: restore "linklayer atm" handling

2013-08-15T08:43:08+00:00

commit 56b765b79 ("htb: improved accuracy at high rates") broke the "linklayer atm" handling. tc class add ... htb rate X ceil Y linklayer atm The linklayer setting is implemented by modifying the rate table which is send to the kernel. No direct parameter were transferred to the kernel indicating the linklayer setting. The commit 56b765b79 ("htb: improved accuracy at high rates") removed the use of the rate table system. To keep compatible with older iproute2 utils, this patch detects the linklayer by parsing the rate table. It also supports future versions of iproute2 to send this linklayer parameter to the kernel directly. This is done by using the __reserved field in struct tc_ratespec, to convey the choosen linklayer option, but only using the lower 4 bits of this field. Linklayer detection is limited to speeds below 100Mbit/s, because at high rates the rtab is gets too inaccurate, so bad that several fields contain the same values, this resembling the ATM detect. Fields even start to contain "0" time to send, e.g. at 1000Mbit/s sending a 96 bytes packet cost "0", thus the rtab have been more broken than we first realized. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller

net_sched: make dev_trans_start return vlan's real dev trans_start

2013-08-05T19:17:42+00:00

Vlan devices are LLTX and don't update their own trans_start, so if dev_trans_start has to be called with a vlan device then 0 or a stale value will be returned. Currently the bonding is the only such user, and it's needed for proper arp monitoring when the slaves are vlans. Fix this by extracting the vlan's real device trans_start. Suggested-by: David Miller Signed-off-by: Nikolay Aleksandrov Acked-by: Veaceslav Falico Signed-off-by: David S. Miller

htb: fix sign extension bug

2013-08-02T21:52:20+00:00

When userspace passes a large priority value the assignment of the unsigned value hopt->prio to signed int cl->prio causes cl->prio to become negative and the comparison is with TC_HTB_NUMPRIO is always false. The result is that HTB crashes by referencing outside the array when processing packets. With this patch the large value wraps around like other values outside the normal range. See: https://bugzilla.kernel.org/show_bug.cgi?id=60669 Signed-off-by: Stephen Hemminger Acked-by: Eric Dumazet Signed-off-by: David S. Miller

net_sched: info leak in atm_tc_dump_class()

2013-07-31T22:04:19+00:00

The "pvc" struct has a hole after pvc.sap_family which is not cleared. Signed-off-by: Dan Carpenter Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller

net_sched: Fix stack info leak in cbq_dump_wrr().

2013-07-30T07:16:21+00:00

Make sure the reserved fields, and padding (if any), are fully initialized. Based upon a patch by Dan Carpenter and feedback from Joe Perches. Signed-off-by: David S. Miller

pkt_sched: sch_qfq: remove a source of high packet delay/jitter

2013-07-18T20:02:00+00:00

QFQ+ inherits from QFQ a design choice that may cause a high packet delay/jitter and a severe short-term unfairness. As QFQ, QFQ+ uses a special quantity, the system virtual time, to track the service provided by the ideal system it approximates. When a packet is dequeued, this quantity must be incremented by the size of the packet, divided by the sum of the weights of the aggregates waiting to be served. Tracking this sum correctly is a non-trivial task, because, to preserve tight service guarantees, the decrement of this sum must be delayed in a special way [1]: this sum can be decremented only after that its value would decrease also in the ideal system approximated by QFQ+. For efficiency, QFQ+ keeps track only of the 'instantaneous' weight sum, increased and decreased immediately as the weight of an aggregate changes, and as an aggregate is created or destroyed (which, in its turn, happens as a consequence of some class being created/destroyed/changed). However, to avoid the problems caused to service guarantees by these immediate decreases, QFQ+ increments the system virtual time using the maximum value allowed for the weight sum, 2^10, in place of the dynamic, instantaneous value. The instantaneous value of the weight sum is used only to check whether a request of weight increase or a class creation can be satisfied. Unfortunately, the problems caused by this choice are worse than the temporary degradation of the service guarantees that may occur, when a class is changed or destroyed, if the instantaneous value of the weight sum was used to update the system virtual time. In fact, the fraction of the link bandwidth guaranteed by QFQ+ to each aggregate is equal to the ratio between the weight of the aggregate and the sum of the weights of the competing aggregates. The packet delay guaranteed to the aggregate is instead inversely proportional to the guaranteed bandwidth. By using the maximum possible value, and not the actual value of the weight sum, QFQ+ provides each aggregate with the worst possible service guarantees, and not with service guarantees related to the actual set of competing aggregates. To see the consequences of this fact, consider the following simple example. Suppose that only the following aggregates are backlogged, i.e., that only the classes in the following aggregates have packets to transmit: one aggregate with weight 10, say A, and ten aggregates with weight 1, say B1, B2, ..., B10. In particular, suppose that these aggregates are always backlogged. Given the weight distribution, the smoothest and fairest service order would be: A B1 A B2 A B3 A B4 A B5 A B6 A B7 A B8 A B9 A B10 A B1 A B2 ... QFQ+ would provide exactly this optimal service if it used the actual value for the weight sum instead of the maximum possible value, i.e., 11 instead of 2^10. In contrast, since QFQ+ uses the latter value, it serves aggregates as follows (easy to prove and to reproduce experimentally): A B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 A A A A A A A A A A B1 B2 ... B10 A A ... By replacing 10 with N in the above example, and by increasing N, one can increase at will the maximum packet delay and the jitter experienced by the classes in aggregate A. This patch addresses this issue by just using the above 'instantaneous' value of the weight sum, instead of the maximum possible value, when updating the system virtual time. After the instantaneous weight sum is decreased, QFQ+ may deviate from the ideal service for a time interval in the order of the time to serve one maximum-size packet for each backlogged class. The worst-case extent of the deviation exhibited by QFQ+ during this time interval [1] is basically the same as of the deviation described above (but, without this patch, QFQ+ suffers from such a deviation all the time). Finally, this patch modifies the comment to the function qfq_slot_insert, to make it coherent with the fact that the weight sum used by QFQ+ can now be lower than the maximum possible value. [1] P. Valente, "Extending WF2Q+ to support a dynamic traffic mix", Proceedings of AAA-IDEA'05, June 2005. Signed-off-by: Paolo Valente Signed-off-by: David S. Miller

pkt_sched: sch_qfq: remove forward declaration of qfq_update_agg_ts

2013-07-11T20:01:07+00:00

This patch removes the forward declaration of qfq_update_agg_ts, by moving the definition of the function above its first call. This patch also removes a useless forward declaration of qfq_schedule_agg. Reported-by: David S. Miller Signed-off-by: Paolo Valente Signed-off-by: David S. Miller

pkt_sched: sch_qfq: improve efficiency of make_eligible

2013-07-11T20:01:07+00:00

In make_eligible, a mask is used to decide which groups must become eligible: the i-th group becomes eligible only if the i-th bit of the mask (from the right) is set. The mask is computed by left-shifting a 1 by a given number of places, and decrementing the result. The shift is performed on a ULL to avoid problems in case the number of places to shift is higher than 31. On a 32-bit machine, this is more costly than working on an UL. This patch replaces such a costly operation with two cheaper branches. The trick is based on the following fact: in case of a shift of at least 32 places, the resulting mask has at least the 32 less significant bits set, whereas the total number of groups is lower than 32. As a consequence, in this case it is enough to just set the 32 less significant bits of the mask with a cheaper ~0UL. In the other case, the shift can be safely performed on a UL. Reported-by: David S. Miller Reported-by: David Laight Signed-off-by: Paolo Valente Signed-off-by: David S. Miller

netem: fix possible NULL deref in netem_dequeue()

2013-07-03T23:52:10+00:00

commit aec0a40a6f7884 ("netem: use rb tree to implement the time queue") added a regression if a child qdisc is attached to netem, as we perform a NULL dereference. Fix this by adding a temporary variable to cache netem_skb_cb(skb)->time_to_send. Reported-by: Dan Carpenter Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

netem: use rb tree to implement the time queue

2013-07-02T01:07:15+00:00

Following typical setup to implement a ~100 ms RTT and big amount of reorders has very poor performance because netem implements the time queue using a linked list. ----------------------------------------------------------- ETH=eth0 IFB=ifb0 modprobe ifb ip link set dev $IFB up tc qdisc add dev $ETH ingress 2>/dev/null tc filter add dev $ETH parent ffff: \ protocol ip u32 match u32 0 0 flowid 1:1 action mirred egress \ redirect dev $IFB ethtool -K $ETH gro off tso off gso off tc qdisc add dev $IFB root netem delay 50ms 10ms limit 100000 tc qd add dev $ETH root netem delay 50ms limit 100000 --------------------------------------------------------- Switch netem time queue to a rb tree, so this kind of setup can work at high speed. Signed-off-by: Eric Dumazet Cc: Stephen Hemminger Signed-off-by: David S. Miller