[PATCH bpf-next 0/2] add xdp_build_skb_from_frame utility routine

[PATCH bpf-next 0/2] add xdp_build_skb_from_frame utility routine

[Lorenzo Bianconi]

Introduce __xdp_build_skb_from_frame and xdp_build_skb_from_frame routines to
build the skb from a xdp_frame. Respect to __xdp_build_skb_from_frame,
xdp_build_skb_from_frame will allocate the skb object.
Rely on __xdp_build_skb_from_frame/xdp_build_skb_from_frame in cpumap and veth
code.

Lorenzo Bianconi (2):
  net: xdp: introduce __xdp_build_skb_from_frame utility routine
  net: xdp: introduce xdp_build_skb_from_frame utility routine

 drivers/net/veth.c  | 18 +++-----------
 include/net/xdp.h   |  5 ++++
 kernel/bpf/cpumap.c | 45 +---------------------------------
 net/core/xdp.c      | 59 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 68 insertions(+), 59 deletions(-)

-- 
2.29.2

[PATCH bpf-next 1/2] net: xdp: introduce __xdp_build_skb_from_frame utility routine

[Lorenzo Bianconi]

Introduce __xdp_build_skb_from_frame utility routine to build
the skb from xdp_frame. Rely on __xdp_build_skb_from_frame in
cpumap code.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 include/net/xdp.h   |  3 +++
 kernel/bpf/cpumap.c | 45 +--------------------------------------------
 net/core/xdp.c      | 44 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 48 insertions(+), 44 deletions(-)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index 600acb307db6..da62fa20fa8a 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -145,6 +145,9 @@ void xdp_warn(const char *msg, const char *func, const int line);
 #define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
 
 struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
+struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
+					   struct sk_buff *skb,
+					   struct net_device *dev);
 
 static inline
 void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index 747313698178..49113880b82a 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -141,49 +141,6 @@ static void cpu_map_kthread_stop(struct work_struct *work)
 	kthread_stop(rcpu->kthread);
 }
 
-static struct sk_buff *cpu_map_build_skb(struct xdp_frame *xdpf,
-					 struct sk_buff *skb)
-{
-	unsigned int hard_start_headroom;
-	unsigned int frame_size;
-	void *pkt_data_start;
-
-	/* Part of headroom was reserved to xdpf */
-	hard_start_headroom = sizeof(struct xdp_frame) +  xdpf->headroom;
-
-	/* Memory size backing xdp_frame data already have reserved
-	 * room for build_skb to place skb_shared_info in tailroom.
-	 */
-	frame_size = xdpf->frame_sz;
-
-	pkt_data_start = xdpf->data - hard_start_headroom;
-	skb = build_skb_around(skb, pkt_data_start, frame_size);
-	if (unlikely(!skb))
-		return NULL;
-
-	skb_reserve(skb, hard_start_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, xdpf->dev_rx);
-
-	/* Optional SKB info, currently missing:
-	 * - HW checksum info		(skb->ip_summed)
-	 * - HW RX hash			(skb_set_hash)
-	 * - RX ring dev queue index	(skb_record_rx_queue)
-	 */
-
-	/* Until page_pool get SKB return path, release DMA here */
-	xdp_release_frame(xdpf);
-
-	/* Allow SKB to reuse area used by xdp_frame */
-	xdp_scrub_frame(xdpf);
-
-	return skb;
-}
-
 static void __cpu_map_ring_cleanup(struct ptr_ring *ring)
 {
 	/* The tear-down procedure should have made sure that queue is
@@ -350,7 +307,7 @@ static int cpu_map_kthread_run(void *data)
 			struct sk_buff *skb = skbs[i];
 			int ret;
 
-			skb = cpu_map_build_skb(xdpf, skb);
+			skb = __xdp_build_skb_from_frame(xdpf, skb, xdpf->dev_rx);
 			if (!skb) {
 				xdp_return_frame(xdpf);
 				continue;
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 3a8c9ab4ecbe..aeb09ed0704c 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -513,3 +513,47 @@ void xdp_warn(const char *msg, const char *func, const int line)
 	WARN(1, "XDP_WARN: %s(line:%d): %s\n", func, line, msg);
 };
 EXPORT_SYMBOL_GPL(xdp_warn);
+
+struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
+					   struct sk_buff *skb,
+					   struct net_device *dev)
+{
+	unsigned int headroom, frame_size;
+	void *hard_start;
+
+	/* Part of headroom was reserved to xdpf */
+	headroom = sizeof(*xdpf) + xdpf->headroom;
+
+	/* Memory size backing xdp_frame data already have reserved
+	 * room for build_skb to place skb_shared_info in tailroom.
+	 */
+	frame_size = xdpf->frame_sz;
+
+	hard_start = xdpf->data - headroom;
+	skb = build_skb_around(skb, hard_start, frame_size);
+	if (unlikely(!skb))
+		return NULL;
+
+	skb_reserve(skb, 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, dev);
+
+	/* Optional SKB info, currently missing:
+	 * - HW checksum info		(skb->ip_summed)
+	 * - HW RX hash			(skb_set_hash)
+	 * - RX ring dev queue index	(skb_record_rx_queue)
+	 */
+
+	/* Until page_pool get SKB return path, release DMA here */
+	xdp_release_frame(xdpf);
+
+	/* Allow SKB to reuse area used by xdp_frame */
+	xdp_scrub_frame(xdpf);
+
+	return skb;
+}
+EXPORT_SYMBOL_GPL(__xdp_build_skb_from_frame);
-- 
2.29.2

Re: [PATCH bpf-next 1/2] net: xdp: introduce __xdp_build_skb_from_frame utility routine

[Jesper Dangaard Brouer]

On Wed, 16 Dec 2020 19:38:33 +0100
Lorenzo Bianconi <lorenzo@kernel.org> wrote:

> Introduce __xdp_build_skb_from_frame utility routine to build
> the skb from xdp_frame. Rely on __xdp_build_skb_from_frame in
> cpumap code.
> 
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
>  include/net/xdp.h   |  3 +++
>  kernel/bpf/cpumap.c | 45 +--------------------------------------------
>  net/core/xdp.c      | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 48 insertions(+), 44 deletions(-)

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>


-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

[PATCH bpf-next 2/2] net: xdp: introduce xdp_build_skb_from_frame utility routine

[Lorenzo Bianconi]

Introduce xdp_build_skb_from_frame utility routine to build the skb
from xdp_frame. Respect to __xdp_build_skb_from_frame,
xdp_build_skb_from_frame will allocate the skb object. Rely on
xdp_build_skb_from_frame in veth driver.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/veth.c | 18 +++---------------
 include/net/xdp.h  |  2 ++
 net/core/xdp.c     | 15 +++++++++++++++
 3 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 02bfcdf50a7a..dbacf90df2b5 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -567,16 +567,10 @@ static struct sk_buff *veth_xdp_rcv_one(struct veth_rq *rq,
 					struct veth_xdp_tx_bq *bq,
 					struct veth_stats *stats)
 {
-	void *hard_start = frame->data - frame->headroom;
-	int len = frame->len, delta = 0;
 	struct xdp_frame orig_frame;
 	struct bpf_prog *xdp_prog;
-	unsigned int headroom;
 	struct sk_buff *skb;
 
-	/* bpf_xdp_adjust_head() assures BPF cannot access xdp_frame area */
-	hard_start -= sizeof(struct xdp_frame);
-
 	rcu_read_lock();
 	xdp_prog = rcu_dereference(rq->xdp_prog);
 	if (likely(xdp_prog)) {
@@ -590,8 +584,8 @@ static struct sk_buff *veth_xdp_rcv_one(struct veth_rq *rq,
 
 		switch (act) {
 		case XDP_PASS:
-			delta = frame->data - xdp.data;
-			len = xdp.data_end - xdp.data;
+			if (xdp_update_frame_from_buff(&xdp, frame))
+				goto err_xdp;
 			break;
 		case XDP_TX:
 			orig_frame = *frame;
@@ -629,18 +623,12 @@ static struct sk_buff *veth_xdp_rcv_one(struct veth_rq *rq,
 	}
 	rcu_read_unlock();
 
-	headroom = sizeof(struct xdp_frame) + frame->headroom - delta;
-	skb = veth_build_skb(hard_start, headroom, len, frame->frame_sz);
+	skb = xdp_build_skb_from_frame(frame, rq->dev);
 	if (!skb) {
 		xdp_return_frame(frame);
 		stats->rx_drops++;
-		goto err;
 	}
 
-	xdp_release_frame(frame);
-	xdp_scrub_frame(frame);
-	skb->protocol = eth_type_trans(skb, rq->dev);
-err:
 	return skb;
 err_xdp:
 	rcu_read_unlock();
diff --git a/include/net/xdp.h b/include/net/xdp.h
index da62fa20fa8a..11ec93f827c0 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -148,6 +148,8 @@ struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
 struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
 					   struct sk_buff *skb,
 					   struct net_device *dev);
+struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
+					 struct net_device *dev);
 
 static inline
 void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
diff --git a/net/core/xdp.c b/net/core/xdp.c
index aeb09ed0704c..0d2630a35c3e 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -557,3 +557,18 @@ struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
 	return skb;
 }
 EXPORT_SYMBOL_GPL(__xdp_build_skb_from_frame);
+
+struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
+					 struct net_device *dev)
+{
+	struct sk_buff *skb;
+
+	skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
+	if (unlikely(!skb))
+		return NULL;
+
+	memset(skb, 0, offsetof(struct sk_buff, tail));
+
+	return __xdp_build_skb_from_frame(xdpf, skb, dev);
+}
+EXPORT_SYMBOL_GPL(xdp_build_skb_from_frame);
-- 
2.29.2

Re: [PATCH bpf-next 2/2] net: xdp: introduce xdp_build_skb_from_frame utility routine

[Toshiaki Makita]

On 2020/12/17 3:38, Lorenzo Bianconi wrote:
> Introduce xdp_build_skb_from_frame utility routine to build the skb
> from xdp_frame. Respect to __xdp_build_skb_from_frame,
> xdp_build_skb_from_frame will allocate the skb object. Rely on
> xdp_build_skb_from_frame in veth driver.
> 
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>

Thanks.
It seems you added missing metadata support in veth_xdp_rcv_one()?
It might be better to note that in the commitlog.

The code looks fine to me.

Reviewed-by: Toshiaki Makita <toshiaki.makita1@gmail.com>

Re: [PATCH bpf-next 2/2] net: xdp: introduce xdp_build_skb_from_frame utility routine

[Jesper Dangaard Brouer]

On Wed, 16 Dec 2020 19:38:34 +0100
Lorenzo Bianconi <lorenzo@kernel.org> wrote:

> Introduce xdp_build_skb_from_frame utility routine to build the skb
> from xdp_frame. Respect to __xdp_build_skb_from_frame,
> xdp_build_skb_from_frame will allocate the skb object. Rely on
> xdp_build_skb_from_frame in veth driver.
> 
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
>  drivers/net/veth.c | 18 +++---------------
>  include/net/xdp.h  |  2 ++
>  net/core/xdp.c     | 15 +++++++++++++++
>  3 files changed, 20 insertions(+), 15 deletions(-)

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [PATCH bpf-next 0/2] add xdp_build_skb_from_frame utility routine

[Lorenzo Bianconi]

[-- Attachment #1: Type: text/plain, Size: 897 bytes --]

> Introduce __xdp_build_skb_from_frame and xdp_build_skb_from_frame routines to
> build the skb from a xdp_frame. Respect to __xdp_build_skb_from_frame,
> xdp_build_skb_from_frame will allocate the skb object.
> Rely on __xdp_build_skb_from_frame/xdp_build_skb_from_frame in cpumap and veth
> code.

Hi Daniel/Alexei,

since this series is marked as "archived" in patchwork, do I need to resubmit it?

Regards,
Lorenzo

> 
> Lorenzo Bianconi (2):
>   net: xdp: introduce __xdp_build_skb_from_frame utility routine
>   net: xdp: introduce xdp_build_skb_from_frame utility routine
> 
>  drivers/net/veth.c  | 18 +++-----------
>  include/net/xdp.h   |  5 ++++
>  kernel/bpf/cpumap.c | 45 +---------------------------------
>  net/core/xdp.c      | 59 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 68 insertions(+), 59 deletions(-)
> 
> -- 
> 2.29.2
> 

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Re: [PATCH bpf-next 0/2] add xdp_build_skb_from_frame utility routine

[Daniel Borkmann]

On 1/12/21 5:08 PM, Lorenzo Bianconi wrote:
>> Introduce __xdp_build_skb_from_frame and xdp_build_skb_from_frame routines to
>> build the skb from a xdp_frame. Respect to __xdp_build_skb_from_frame,
>> xdp_build_skb_from_frame will allocate the skb object.
>> Rely on __xdp_build_skb_from_frame/xdp_build_skb_from_frame in cpumap and veth
>> code.
> 
> since this series is marked as "archived" in patchwork, do I need to resubmit it?

Yes please do, afaik there was some minor feedback from Toshiaki which was not yet
addressed from your side.

Thanks,
Daniel

Re: [PATCH bpf-next 0/2] add xdp_build_skb_from_frame utility routine

[Lorenzo Bianconi]

[-- Attachment #1: Type: text/plain, Size: 652 bytes --]

> On 1/12/21 5:08 PM, Lorenzo Bianconi wrote:
> > > Introduce __xdp_build_skb_from_frame and xdp_build_skb_from_frame routines to
> > > build the skb from a xdp_frame. Respect to __xdp_build_skb_from_frame,
> > > xdp_build_skb_from_frame will allocate the skb object.
> > > Rely on __xdp_build_skb_from_frame/xdp_build_skb_from_frame in cpumap and veth
> > > code.
> > 
> > since this series is marked as "archived" in patchwork, do I need to resubmit it?
> 
> Yes please do, afaik there was some minor feedback from Toshiaki which was not yet
> addressed from your side.

ack, will do.

Regards,
Lorenzo

> 
> Thanks,
> Daniel
> 

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