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bpf: cpumap convert to use generic xdp_frame
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The generic xdp_frame format, was inspired by the cpumap own internal
xdp_pkt format.  It is now time to convert it over to the generic
xdp_frame format.  The cpumap needs one extra field dev_rx.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Jesper Dangaard Brouer authored and David S. Miller committed Apr 17, 2018
1 parent cac320c commit 70280ed
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Showing 2 changed files with 29 additions and 72 deletions.
1 change: 1 addition & 0 deletions include/net/xdp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,7 @@ struct xdp_frame {
* while mem info is valid on remote CPU.
*/
struct xdp_mem_info mem;
struct net_device *dev_rx; /* used by cpumap */
};

/* Convert xdp_buff to xdp_frame */
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100 changes: 28 additions & 72 deletions kernel/bpf/cpumap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -159,52 +159,8 @@ static void cpu_map_kthread_stop(struct work_struct *work)
kthread_stop(rcpu->kthread);
}

/* For now, xdp_pkt is a cpumap internal data structure, with info
* carried between enqueue to dequeue. It is mapped into the top
* headroom of the packet, to avoid allocating separate mem.
*/
struct xdp_pkt {
void *data;
u16 len;
u16 headroom;
u16 metasize;
/* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
* while mem info is valid on remote CPU.
*/
struct xdp_mem_info mem;
struct net_device *dev_rx;
};

/* Convert xdp_buff to xdp_pkt */
static struct xdp_pkt *convert_to_xdp_pkt(struct xdp_buff *xdp)
{
struct xdp_pkt *xdp_pkt;
int metasize;
int headroom;

/* Assure headroom is available for storing info */
headroom = xdp->data - xdp->data_hard_start;
metasize = xdp->data - xdp->data_meta;
metasize = metasize > 0 ? metasize : 0;
if (unlikely((headroom - metasize) < sizeof(*xdp_pkt)))
return NULL;

/* Store info in top of packet */
xdp_pkt = xdp->data_hard_start;

xdp_pkt->data = xdp->data;
xdp_pkt->len = xdp->data_end - xdp->data;
xdp_pkt->headroom = headroom - sizeof(*xdp_pkt);
xdp_pkt->metasize = metasize;

/* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
xdp_pkt->mem = xdp->rxq->mem;

return xdp_pkt;
}

static struct sk_buff *cpu_map_build_skb(struct bpf_cpu_map_entry *rcpu,
struct xdp_pkt *xdp_pkt)
struct xdp_frame *xdpf)
{
unsigned int frame_size;
void *pkt_data_start;
Expand All @@ -219,29 +175,29 @@ static struct sk_buff *cpu_map_build_skb(struct bpf_cpu_map_entry *rcpu,
* would be preferred to set frame_size to 2048 or 4096
* depending on the driver.
* frame_size = 2048;
* frame_len = frame_size - sizeof(*xdp_pkt);
* frame_len = frame_size - sizeof(*xdp_frame);
*
* Instead, with info avail, skb_shared_info in placed after
* packet len. This, unfortunately fakes the truesize.
* Another disadvantage of this approach, the skb_shared_info
* is not at a fixed memory location, with mixed length
* packets, which is bad for cache-line hotness.
*/
frame_size = SKB_DATA_ALIGN(xdp_pkt->len) + xdp_pkt->headroom +
frame_size = SKB_DATA_ALIGN(xdpf->len) + xdpf->headroom +
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

pkt_data_start = xdp_pkt->data - xdp_pkt->headroom;
pkt_data_start = xdpf->data - xdpf->headroom;
skb = build_skb(pkt_data_start, frame_size);
if (!skb)
return NULL;

skb_reserve(skb, xdp_pkt->headroom);
__skb_put(skb, xdp_pkt->len);
if (xdp_pkt->metasize)
skb_metadata_set(skb, xdp_pkt->metasize);
skb_reserve(skb, xdpf->headroom);
__skb_put(skb, xdpf->len);
if (xdpf->metasize)
skb_metadata_set(skb, xdpf->metasize);

/* Essential SKB info: protocol and skb->dev */
skb->protocol = eth_type_trans(skb, xdp_pkt->dev_rx);
skb->protocol = eth_type_trans(skb, xdpf->dev_rx);

/* Optional SKB info, currently missing:
* - HW checksum info (skb->ip_summed)
Expand All @@ -259,11 +215,11 @@ static void __cpu_map_ring_cleanup(struct ptr_ring *ring)
* invoked cpu_map_kthread_stop(). Catch any broken behaviour
* gracefully and warn once.
*/
struct xdp_pkt *xdp_pkt;
struct xdp_frame *xdpf;

while ((xdp_pkt = ptr_ring_consume(ring)))
if (WARN_ON_ONCE(xdp_pkt))
xdp_return_frame(xdp_pkt, &xdp_pkt->mem);
while ((xdpf = ptr_ring_consume(ring)))
if (WARN_ON_ONCE(xdpf))
xdp_return_frame(xdpf->data, &xdpf->mem);
}

static void put_cpu_map_entry(struct bpf_cpu_map_entry *rcpu)
Expand All @@ -290,7 +246,7 @@ static int cpu_map_kthread_run(void *data)
*/
while (!kthread_should_stop() || !__ptr_ring_empty(rcpu->queue)) {
unsigned int processed = 0, drops = 0, sched = 0;
struct xdp_pkt *xdp_pkt;
struct xdp_frame *xdpf;

/* Release CPU reschedule checks */
if (__ptr_ring_empty(rcpu->queue)) {
Expand All @@ -313,13 +269,13 @@ static int cpu_map_kthread_run(void *data)
* kthread CPU pinned. Lockless access to ptr_ring
* consume side valid as no-resize allowed of queue.
*/
while ((xdp_pkt = __ptr_ring_consume(rcpu->queue))) {
while ((xdpf = __ptr_ring_consume(rcpu->queue))) {
struct sk_buff *skb;
int ret;

skb = cpu_map_build_skb(rcpu, xdp_pkt);
skb = cpu_map_build_skb(rcpu, xdpf);
if (!skb) {
xdp_return_frame(xdp_pkt, &xdp_pkt->mem);
xdp_return_frame(xdpf->data, &xdpf->mem);
continue;
}

Expand Down Expand Up @@ -616,13 +572,13 @@ static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu,
spin_lock(&q->producer_lock);

for (i = 0; i < bq->count; i++) {
struct xdp_pkt *xdp_pkt = bq->q[i];
struct xdp_frame *xdpf = bq->q[i];
int err;

err = __ptr_ring_produce(q, xdp_pkt);
err = __ptr_ring_produce(q, xdpf);
if (err) {
drops++;
xdp_return_frame(xdp_pkt->data, &xdp_pkt->mem);
xdp_return_frame(xdpf->data, &xdpf->mem);
}
processed++;
}
Expand All @@ -637,7 +593,7 @@ static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu,
/* Runs under RCU-read-side, plus in softirq under NAPI protection.
* Thus, safe percpu variable access.
*/
static int bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_pkt *xdp_pkt)
static int bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf)
{
struct xdp_bulk_queue *bq = this_cpu_ptr(rcpu->bulkq);

Expand All @@ -648,28 +604,28 @@ static int bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_pkt *xdp_pkt)
* driver to code invoking us to finished, due to driver
* (e.g. ixgbe) recycle tricks based on page-refcnt.
*
* Thus, incoming xdp_pkt is always queued here (else we race
* Thus, incoming xdp_frame is always queued here (else we race
* with another CPU on page-refcnt and remaining driver code).
* Queue time is very short, as driver will invoke flush
* operation, when completing napi->poll call.
*/
bq->q[bq->count++] = xdp_pkt;
bq->q[bq->count++] = xdpf;
return 0;
}

int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp,
struct net_device *dev_rx)
{
struct xdp_pkt *xdp_pkt;
struct xdp_frame *xdpf;

xdp_pkt = convert_to_xdp_pkt(xdp);
if (unlikely(!xdp_pkt))
xdpf = convert_to_xdp_frame(xdp);
if (unlikely(!xdpf))
return -EOVERFLOW;

/* Info needed when constructing SKB on remote CPU */
xdp_pkt->dev_rx = dev_rx;
xdpf->dev_rx = dev_rx;

bq_enqueue(rcpu, xdp_pkt);
bq_enqueue(rcpu, xdpf);
return 0;
}

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