* [PATCH bpf-next V2] bpf: add skb->queue_mapping write access from tc clsact
@ 2019-02-19 18:53 Jesper Dangaard Brouer
2019-02-19 20:59 ` Daniel Borkmann
0 siblings, 1 reply; 2+ messages in thread
From: Jesper Dangaard Brouer @ 2019-02-19 18:53 UTC (permalink / raw)
To: netdev, Daniel Borkmann, Alexei Starovoitov; +Cc: Jesper Dangaard Brouer
The skb->queue_mapping already have read access, via __sk_buff->queue_mapping.
This patch allow BPF tc qdisc clsact write access to the queue_mapping via
tc_cls_act_is_valid_access. Also handle that the value NO_QUEUE_MAPPING
is not allowed.
It is already possible to change this via TC filter action skbedit
tc-skbedit(8). Due to the lack of TC examples, lets show one:
# tc qdisc add dev ixgbe1 clsact
# tc filter add dev ixgbe1 ingress matchall action skbedit queue_mapping 5
# tc filter list dev ixgbe1 ingress
The most common mistake is that XPS (Transmit Packet Steering) takes
precedence over setting skb->queue_mapping. XPS is configured per DEVICE
via /sys/class/net/DEVICE/queues/tx-*/xps_cpus via a CPU hex mask. To
disable set mask=00.
The purpose of changing skb->queue_mapping is to influence the selection of
the net_device "txq" (struct netdev_queue), which influence selection of
the qdisc "root_lock" (via txq->qdisc->q.lock) and txq->_xmit_lock. When
using the MQ qdisc the txq->qdisc points to different qdiscs and associated
locks, and HARD_TX_LOCK (txq->_xmit_lock), allowing for CPU scalability.
Due to lack of TC examples, lets show howto attach clsact BPF programs:
# tc qdisc add dev ixgbe2 clsact
# tc filter add dev ixgbe2 egress bpf da obj XXX_kern.o sec tc_qmap2cpu
# tc filter list dev ixgbe2 egress
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
net/core/filter.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 353735575204..8b80cdf96595 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6238,6 +6238,7 @@ static bool tc_cls_act_is_valid_access(int off, int size,
case bpf_ctx_range(struct __sk_buff, tc_classid):
case bpf_ctx_range_till(struct __sk_buff, cb[0], cb[4]):
case bpf_ctx_range(struct __sk_buff, tstamp):
+ case bpf_ctx_range(struct __sk_buff, queue_mapping):
break;
default:
return false;
@@ -6642,9 +6643,18 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
break;
case offsetof(struct __sk_buff, queue_mapping):
- *insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->src_reg,
- bpf_target_off(struct sk_buff, queue_mapping, 2,
- target_size));
+ if (type == BPF_WRITE) {
+ *insn++ = BPF_JMP_IMM(BPF_JGE, si->src_reg, NO_QUEUE_MAPPING, 1);
+ *insn++ = BPF_STX_MEM(BPF_H, si->dst_reg, si->src_reg,
+ bpf_target_off(struct sk_buff,
+ queue_mapping,
+ 2, target_size));
+ } else {
+ *insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->src_reg,
+ bpf_target_off(struct sk_buff,
+ queue_mapping,
+ 2, target_size));
+ }
break;
case offsetof(struct __sk_buff, vlan_present):
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH bpf-next V2] bpf: add skb->queue_mapping write access from tc clsact
2019-02-19 18:53 [PATCH bpf-next V2] bpf: add skb->queue_mapping write access from tc clsact Jesper Dangaard Brouer
@ 2019-02-19 20:59 ` Daniel Borkmann
0 siblings, 0 replies; 2+ messages in thread
From: Daniel Borkmann @ 2019-02-19 20:59 UTC (permalink / raw)
To: Jesper Dangaard Brouer, netdev, Daniel Borkmann, Alexei Starovoitov
On 02/19/2019 07:53 PM, Jesper Dangaard Brouer wrote:
> The skb->queue_mapping already have read access, via __sk_buff->queue_mapping.
>
> This patch allow BPF tc qdisc clsact write access to the queue_mapping via
> tc_cls_act_is_valid_access. Also handle that the value NO_QUEUE_MAPPING
> is not allowed.
>
> It is already possible to change this via TC filter action skbedit
> tc-skbedit(8). Due to the lack of TC examples, lets show one:
>
> # tc qdisc add dev ixgbe1 clsact
> # tc filter add dev ixgbe1 ingress matchall action skbedit queue_mapping 5
> # tc filter list dev ixgbe1 ingress
>
> The most common mistake is that XPS (Transmit Packet Steering) takes
> precedence over setting skb->queue_mapping. XPS is configured per DEVICE
> via /sys/class/net/DEVICE/queues/tx-*/xps_cpus via a CPU hex mask. To
> disable set mask=00.
>
> The purpose of changing skb->queue_mapping is to influence the selection of
> the net_device "txq" (struct netdev_queue), which influence selection of
> the qdisc "root_lock" (via txq->qdisc->q.lock) and txq->_xmit_lock. When
> using the MQ qdisc the txq->qdisc points to different qdiscs and associated
> locks, and HARD_TX_LOCK (txq->_xmit_lock), allowing for CPU scalability.
>
> Due to lack of TC examples, lets show howto attach clsact BPF programs:
>
> # tc qdisc add dev ixgbe2 clsact
> # tc filter add dev ixgbe2 egress bpf da obj XXX_kern.o sec tc_qmap2cpu
> # tc filter list dev ixgbe2 egress
>
> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Applied, thanks!
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2019-02-19 20:59 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-02-19 18:53 [PATCH bpf-next V2] bpf: add skb->queue_mapping write access from tc clsact Jesper Dangaard Brouer
2019-02-19 20:59 ` Daniel Borkmann
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).