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* [PATCH net v3] igb: Fix XDP with PTP enabled
@ 2021-04-22  5:26 Kurt Kanzenbach
  2021-04-22 10:11 ` Maciej Fijalkowski
  0 siblings, 1 reply; 4+ messages in thread
From: Kurt Kanzenbach @ 2021-04-22  5:26 UTC (permalink / raw)
  To: Jesse Brandeburg, Tony Nguyen, David S. Miller, Jakub Kicinski
  Cc: Alexei Starovoitov, Daniel Borkmann, Jesper Dangaard Brouer,
	John Fastabend, Sven Auhagen, intel-wired-lan, netdev, bpf,
	Ilias Apalodimas, Lorenzo Bianconi, Sebastian Andrzej Siewior,
	Richard Cochran, Alexander Duyck, Kurt Kanzenbach

When using native XDP with the igb driver, the XDP frame data doesn't point to
the beginning of the packet. It's off by 16 bytes. Everything works as expected
with XDP skb mode.

Actually these 16 bytes are used to store the packet timestamps. Therefore, pull
the timestamp before executing any XDP operations and adjust all other code
accordingly. The igc driver does it like that as well.

Tested with Intel i210 card and AF_XDP sockets.

Fixes: 9cbc948b5a20 ("igb: add XDP support")
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
---

Changes since v2:

 * Check timestamp for validity (Nguyen, Anthony L)

Changes since v1:

 * Use xdp_prepare_buff() (Lorenzo Bianconi)

Changes since RFC:

 * Removed unused return value definitions (Alexander Duyck)

Previous versions:

 * https://lkml.kernel.org/netdev/20210419072332.7246-1-kurt@linutronix.de/
 * https://lkml.kernel.org/netdev/20210415092145.27322-1-kurt@linutronix.de/
 * https://lkml.kernel.org/netdev/20210412101713.15161-1-kurt@linutronix.de/

 drivers/net/ethernet/intel/igb/igb.h      |  3 +-
 drivers/net/ethernet/intel/igb/igb_main.c | 45 +++++++++++++----------
 drivers/net/ethernet/intel/igb/igb_ptp.c  | 21 ++++-------
 3 files changed, 34 insertions(+), 35 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
index 7bda8c5edea5..72cf967c1a00 100644
--- a/drivers/net/ethernet/intel/igb/igb.h
+++ b/drivers/net/ethernet/intel/igb/igb.h
@@ -748,8 +748,7 @@ void igb_ptp_suspend(struct igb_adapter *adapter);
 void igb_ptp_rx_hang(struct igb_adapter *adapter);
 void igb_ptp_tx_hang(struct igb_adapter *adapter);
 void igb_ptp_rx_rgtstamp(struct igb_q_vector *q_vector, struct sk_buff *skb);
-int igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
-			struct sk_buff *skb);
+ktime_t igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va);
 int igb_ptp_set_ts_config(struct net_device *netdev, struct ifreq *ifr);
 int igb_ptp_get_ts_config(struct net_device *netdev, struct ifreq *ifr);
 void igb_set_flag_queue_pairs(struct igb_adapter *, const u32);
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index a45cd2b416c8..13595618f9e3 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -8281,7 +8281,7 @@ static void igb_add_rx_frag(struct igb_ring *rx_ring,
 static struct sk_buff *igb_construct_skb(struct igb_ring *rx_ring,
 					 struct igb_rx_buffer *rx_buffer,
 					 struct xdp_buff *xdp,
-					 union e1000_adv_rx_desc *rx_desc)
+					 ktime_t timestamp)
 {
 #if (PAGE_SIZE < 8192)
 	unsigned int truesize = igb_rx_pg_size(rx_ring) / 2;
@@ -8301,12 +8301,8 @@ static struct sk_buff *igb_construct_skb(struct igb_ring *rx_ring,
 	if (unlikely(!skb))
 		return NULL;
 
-	if (unlikely(igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP))) {
-		if (!igb_ptp_rx_pktstamp(rx_ring->q_vector, xdp->data, skb)) {
-			xdp->data += IGB_TS_HDR_LEN;
-			size -= IGB_TS_HDR_LEN;
-		}
-	}
+	if (timestamp)
+		skb_hwtstamps(skb)->hwtstamp = timestamp;
 
 	/* Determine available headroom for copy */
 	headlen = size;
@@ -8337,7 +8333,7 @@ static struct sk_buff *igb_construct_skb(struct igb_ring *rx_ring,
 static struct sk_buff *igb_build_skb(struct igb_ring *rx_ring,
 				     struct igb_rx_buffer *rx_buffer,
 				     struct xdp_buff *xdp,
-				     union e1000_adv_rx_desc *rx_desc)
+				     ktime_t timestamp)
 {
 #if (PAGE_SIZE < 8192)
 	unsigned int truesize = igb_rx_pg_size(rx_ring) / 2;
@@ -8364,11 +8360,8 @@ static struct sk_buff *igb_build_skb(struct igb_ring *rx_ring,
 	if (metasize)
 		skb_metadata_set(skb, metasize);
 
-	/* pull timestamp out of packet data */
-	if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
-		if (!igb_ptp_rx_pktstamp(rx_ring->q_vector, skb->data, skb))
-			__skb_pull(skb, IGB_TS_HDR_LEN);
-	}
+	if (timestamp)
+		skb_hwtstamps(skb)->hwtstamp = timestamp;
 
 	/* update buffer offset */
 #if (PAGE_SIZE < 8192)
@@ -8683,7 +8676,10 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 	while (likely(total_packets < budget)) {
 		union e1000_adv_rx_desc *rx_desc;
 		struct igb_rx_buffer *rx_buffer;
+		ktime_t timestamp = 0;
+		int pkt_offset = 0;
 		unsigned int size;
+		void *pktbuf;
 
 		/* return some buffers to hardware, one at a time is too slow */
 		if (cleaned_count >= IGB_RX_BUFFER_WRITE) {
@@ -8703,14 +8699,24 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 		dma_rmb();
 
 		rx_buffer = igb_get_rx_buffer(rx_ring, size, &rx_buf_pgcnt);
+		pktbuf = page_address(rx_buffer->page) + rx_buffer->page_offset;
+
+		/* pull rx packet timestamp if available and valid */
+		if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
+			timestamp = igb_ptp_rx_pktstamp(rx_ring->q_vector,
+							pktbuf);
+
+			if (timestamp) {
+				pkt_offset += IGB_TS_HDR_LEN;
+				size -= IGB_TS_HDR_LEN;
+			}
+		}
 
 		/* retrieve a buffer from the ring */
 		if (!skb) {
-			unsigned int offset = igb_rx_offset(rx_ring);
-			unsigned char *hard_start;
+			unsigned char *hard_start = pktbuf - igb_rx_offset(rx_ring);
+			unsigned int offset = pkt_offset + igb_rx_offset(rx_ring);
 
-			hard_start = page_address(rx_buffer->page) +
-				     rx_buffer->page_offset - offset;
 			xdp_prepare_buff(&xdp, hard_start, offset, size, true);
 #if (PAGE_SIZE > 4096)
 			/* At larger PAGE_SIZE, frame_sz depend on len size */
@@ -8733,10 +8739,11 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 		} else if (skb)
 			igb_add_rx_frag(rx_ring, rx_buffer, skb, size);
 		else if (ring_uses_build_skb(rx_ring))
-			skb = igb_build_skb(rx_ring, rx_buffer, &xdp, rx_desc);
+			skb = igb_build_skb(rx_ring, rx_buffer, &xdp,
+					    timestamp);
 		else
 			skb = igb_construct_skb(rx_ring, rx_buffer,
-						&xdp, rx_desc);
+						&xdp, timestamp);
 
 		/* exit if we failed to retrieve a buffer */
 		if (!skb) {
diff --git a/drivers/net/ethernet/intel/igb/igb_ptp.c b/drivers/net/ethernet/intel/igb/igb_ptp.c
index 86a576201f5f..8e23df7da641 100644
--- a/drivers/net/ethernet/intel/igb/igb_ptp.c
+++ b/drivers/net/ethernet/intel/igb/igb_ptp.c
@@ -856,30 +856,26 @@ static void igb_ptp_tx_hwtstamp(struct igb_adapter *adapter)
 	dev_kfree_skb_any(skb);
 }
 
-#define IGB_RET_PTP_DISABLED 1
-#define IGB_RET_PTP_INVALID 2
-
 /**
  * igb_ptp_rx_pktstamp - retrieve Rx per packet timestamp
  * @q_vector: Pointer to interrupt specific structure
  * @va: Pointer to address containing Rx buffer
- * @skb: Buffer containing timestamp and packet
  *
  * This function is meant to retrieve a timestamp from the first buffer of an
  * incoming frame.  The value is stored in little endian format starting on
  * byte 8
  *
- * Returns: 0 if success, nonzero if failure
+ * Returns: 0 on failure, timestamp on success
  **/
-int igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
-			struct sk_buff *skb)
+ktime_t igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va)
 {
 	struct igb_adapter *adapter = q_vector->adapter;
+	struct skb_shared_hwtstamps ts;
 	__le64 *regval = (__le64 *)va;
 	int adjust = 0;
 
 	if (!(adapter->ptp_flags & IGB_PTP_ENABLED))
-		return IGB_RET_PTP_DISABLED;
+		return 0;
 
 	/* The timestamp is recorded in little endian format.
 	 * DWORD: 0        1        2        3
@@ -888,10 +884,9 @@ int igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
 
 	/* check reserved dwords are zero, be/le doesn't matter for zero */
 	if (regval[0])
-		return IGB_RET_PTP_INVALID;
+		return 0;
 
-	igb_ptp_systim_to_hwtstamp(adapter, skb_hwtstamps(skb),
-				   le64_to_cpu(regval[1]));
+	igb_ptp_systim_to_hwtstamp(adapter, &ts, le64_to_cpu(regval[1]));
 
 	/* adjust timestamp for the RX latency based on link speed */
 	if (adapter->hw.mac.type == e1000_i210) {
@@ -907,10 +902,8 @@ int igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
 			break;
 		}
 	}
-	skb_hwtstamps(skb)->hwtstamp =
-		ktime_sub_ns(skb_hwtstamps(skb)->hwtstamp, adjust);
 
-	return 0;
+	return ktime_sub_ns(ts.hwtstamp, adjust);
 }
 
 /**
-- 
2.20.1


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH net v3] igb: Fix XDP with PTP enabled
  2021-04-22  5:26 [PATCH net v3] igb: Fix XDP with PTP enabled Kurt Kanzenbach
@ 2021-04-22 10:11 ` Maciej Fijalkowski
  2021-04-23  6:45   ` Kurt Kanzenbach
  0 siblings, 1 reply; 4+ messages in thread
From: Maciej Fijalkowski @ 2021-04-22 10:11 UTC (permalink / raw)
  To: Kurt Kanzenbach
  Cc: Jesse Brandeburg, Tony Nguyen, David S. Miller, Jakub Kicinski,
	Alexei Starovoitov, Daniel Borkmann, Jesper Dangaard Brouer,
	John Fastabend, Sven Auhagen, intel-wired-lan, netdev, bpf,
	Ilias Apalodimas, Lorenzo Bianconi, Sebastian Andrzej Siewior,
	Richard Cochran, Alexander Duyck

On Thu, Apr 22, 2021 at 07:26:17AM +0200, Kurt Kanzenbach wrote:
> When using native XDP with the igb driver, the XDP frame data doesn't point to
> the beginning of the packet. It's off by 16 bytes. Everything works as expected
> with XDP skb mode.
> 
> Actually these 16 bytes are used to store the packet timestamps. Therefore, pull
> the timestamp before executing any XDP operations and adjust all other code
> accordingly. The igc driver does it like that as well.
> 
> Tested with Intel i210 card and AF_XDP sockets.
> 
> Fixes: 9cbc948b5a20 ("igb: add XDP support")
> Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
> ---
> 
> Changes since v2:
> 
>  * Check timestamp for validity (Nguyen, Anthony L)
> 
> Changes since v1:
> 
>  * Use xdp_prepare_buff() (Lorenzo Bianconi)
> 
> Changes since RFC:
> 
>  * Removed unused return value definitions (Alexander Duyck)
> 
> Previous versions:
> 
>  * https://lkml.kernel.org/netdev/20210419072332.7246-1-kurt@linutronix.de/
>  * https://lkml.kernel.org/netdev/20210415092145.27322-1-kurt@linutronix.de/
>  * https://lkml.kernel.org/netdev/20210412101713.15161-1-kurt@linutronix.de/
> 
>  drivers/net/ethernet/intel/igb/igb.h      |  3 +-
>  drivers/net/ethernet/intel/igb/igb_main.c | 45 +++++++++++++----------
>  drivers/net/ethernet/intel/igb/igb_ptp.c  | 21 ++++-------
>  3 files changed, 34 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
> index 7bda8c5edea5..72cf967c1a00 100644
> --- a/drivers/net/ethernet/intel/igb/igb.h
> +++ b/drivers/net/ethernet/intel/igb/igb.h
> @@ -748,8 +748,7 @@ void igb_ptp_suspend(struct igb_adapter *adapter);
>  void igb_ptp_rx_hang(struct igb_adapter *adapter);
>  void igb_ptp_tx_hang(struct igb_adapter *adapter);
>  void igb_ptp_rx_rgtstamp(struct igb_q_vector *q_vector, struct sk_buff *skb);
> -int igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
> -			struct sk_buff *skb);
> +ktime_t igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va);
>  int igb_ptp_set_ts_config(struct net_device *netdev, struct ifreq *ifr);
>  int igb_ptp_get_ts_config(struct net_device *netdev, struct ifreq *ifr);
>  void igb_set_flag_queue_pairs(struct igb_adapter *, const u32);
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
> index a45cd2b416c8..13595618f9e3 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -8281,7 +8281,7 @@ static void igb_add_rx_frag(struct igb_ring *rx_ring,
>  static struct sk_buff *igb_construct_skb(struct igb_ring *rx_ring,
>  					 struct igb_rx_buffer *rx_buffer,
>  					 struct xdp_buff *xdp,
> -					 union e1000_adv_rx_desc *rx_desc)
> +					 ktime_t timestamp)
>  {
>  #if (PAGE_SIZE < 8192)
>  	unsigned int truesize = igb_rx_pg_size(rx_ring) / 2;
> @@ -8301,12 +8301,8 @@ static struct sk_buff *igb_construct_skb(struct igb_ring *rx_ring,
>  	if (unlikely(!skb))
>  		return NULL;
>  
> -	if (unlikely(igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP))) {
> -		if (!igb_ptp_rx_pktstamp(rx_ring->q_vector, xdp->data, skb)) {
> -			xdp->data += IGB_TS_HDR_LEN;
> -			size -= IGB_TS_HDR_LEN;
> -		}
> -	}
> +	if (timestamp)
> +		skb_hwtstamps(skb)->hwtstamp = timestamp;
>  
>  	/* Determine available headroom for copy */
>  	headlen = size;
> @@ -8337,7 +8333,7 @@ static struct sk_buff *igb_construct_skb(struct igb_ring *rx_ring,
>  static struct sk_buff *igb_build_skb(struct igb_ring *rx_ring,
>  				     struct igb_rx_buffer *rx_buffer,
>  				     struct xdp_buff *xdp,
> -				     union e1000_adv_rx_desc *rx_desc)
> +				     ktime_t timestamp)
>  {
>  #if (PAGE_SIZE < 8192)
>  	unsigned int truesize = igb_rx_pg_size(rx_ring) / 2;
> @@ -8364,11 +8360,8 @@ static struct sk_buff *igb_build_skb(struct igb_ring *rx_ring,
>  	if (metasize)
>  		skb_metadata_set(skb, metasize);
>  
> -	/* pull timestamp out of packet data */
> -	if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
> -		if (!igb_ptp_rx_pktstamp(rx_ring->q_vector, skb->data, skb))
> -			__skb_pull(skb, IGB_TS_HDR_LEN);
> -	}
> +	if (timestamp)
> +		skb_hwtstamps(skb)->hwtstamp = timestamp;
>  
>  	/* update buffer offset */
>  #if (PAGE_SIZE < 8192)
> @@ -8683,7 +8676,10 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
>  	while (likely(total_packets < budget)) {
>  		union e1000_adv_rx_desc *rx_desc;
>  		struct igb_rx_buffer *rx_buffer;
> +		ktime_t timestamp = 0;
> +		int pkt_offset = 0;
>  		unsigned int size;
> +		void *pktbuf;
>  
>  		/* return some buffers to hardware, one at a time is too slow */
>  		if (cleaned_count >= IGB_RX_BUFFER_WRITE) {
> @@ -8703,14 +8699,24 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
>  		dma_rmb();
>  
>  		rx_buffer = igb_get_rx_buffer(rx_ring, size, &rx_buf_pgcnt);
> +		pktbuf = page_address(rx_buffer->page) + rx_buffer->page_offset;
> +
> +		/* pull rx packet timestamp if available and valid */
> +		if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
> +			timestamp = igb_ptp_rx_pktstamp(rx_ring->q_vector,
> +							pktbuf);
> +
> +			if (timestamp) {
> +				pkt_offset += IGB_TS_HDR_LEN;
> +				size -= IGB_TS_HDR_LEN;
> +			}
> +		}

Small nit: since this is a hot path, maybe we could omit the additional
branch that you're introducing above and make igb_ptp_rx_pktstamp() to
return either 0 for error cases and IGB_TS_HDR_LEN if timestamp was fine?
timestamp itself would be passed as an arg.

So:
		if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
			ts_offset = igb_ptp_rx_pktstamp(rx_ring->q_vector,
							pktbuf, &timestamp);
			pkt_offset += ts_offset;
			size -= ts_offset;
		}

Thoughts? I feel like if we see that desc has timestamp enabled then let's
optimize it for successful case.

>  
>  		/* retrieve a buffer from the ring */
>  		if (!skb) {
> -			unsigned int offset = igb_rx_offset(rx_ring);
> -			unsigned char *hard_start;
> +			unsigned char *hard_start = pktbuf - igb_rx_offset(rx_ring);
> +			unsigned int offset = pkt_offset + igb_rx_offset(rx_ring);

Probably we could do something similar in flavour of:
https://lore.kernel.org/bpf/20210118151318.12324-10-maciej.fijalkowski@intel.com/

which broke XDP_REDIRECT and got fixed in:
https://lore.kernel.org/bpf/20210303153928.11764-2-maciej.fijalkowski@intel.com/

You get the idea.

>  
> -			hard_start = page_address(rx_buffer->page) +
> -				     rx_buffer->page_offset - offset;
>  			xdp_prepare_buff(&xdp, hard_start, offset, size, true);
>  #if (PAGE_SIZE > 4096)
>  			/* At larger PAGE_SIZE, frame_sz depend on len size */
> @@ -8733,10 +8739,11 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
>  		} else if (skb)
>  			igb_add_rx_frag(rx_ring, rx_buffer, skb, size);
>  		else if (ring_uses_build_skb(rx_ring))
> -			skb = igb_build_skb(rx_ring, rx_buffer, &xdp, rx_desc);
> +			skb = igb_build_skb(rx_ring, rx_buffer, &xdp,
> +					    timestamp);
>  		else
>  			skb = igb_construct_skb(rx_ring, rx_buffer,
> -						&xdp, rx_desc);
> +						&xdp, timestamp);
>  
>  		/* exit if we failed to retrieve a buffer */
>  		if (!skb) {
> diff --git a/drivers/net/ethernet/intel/igb/igb_ptp.c b/drivers/net/ethernet/intel/igb/igb_ptp.c
> index 86a576201f5f..8e23df7da641 100644
> --- a/drivers/net/ethernet/intel/igb/igb_ptp.c
> +++ b/drivers/net/ethernet/intel/igb/igb_ptp.c
> @@ -856,30 +856,26 @@ static void igb_ptp_tx_hwtstamp(struct igb_adapter *adapter)
>  	dev_kfree_skb_any(skb);
>  }
>  
> -#define IGB_RET_PTP_DISABLED 1
> -#define IGB_RET_PTP_INVALID 2
> -
>  /**
>   * igb_ptp_rx_pktstamp - retrieve Rx per packet timestamp
>   * @q_vector: Pointer to interrupt specific structure
>   * @va: Pointer to address containing Rx buffer
> - * @skb: Buffer containing timestamp and packet
>   *
>   * This function is meant to retrieve a timestamp from the first buffer of an
>   * incoming frame.  The value is stored in little endian format starting on
>   * byte 8
>   *
> - * Returns: 0 if success, nonzero if failure
> + * Returns: 0 on failure, timestamp on success
>   **/
> -int igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
> -			struct sk_buff *skb)
> +ktime_t igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va)
>  {
>  	struct igb_adapter *adapter = q_vector->adapter;
> +	struct skb_shared_hwtstamps ts;
>  	__le64 *regval = (__le64 *)va;
>  	int adjust = 0;
>  
>  	if (!(adapter->ptp_flags & IGB_PTP_ENABLED))
> -		return IGB_RET_PTP_DISABLED;
> +		return 0;
>  
>  	/* The timestamp is recorded in little endian format.
>  	 * DWORD: 0        1        2        3
> @@ -888,10 +884,9 @@ int igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
>  
>  	/* check reserved dwords are zero, be/le doesn't matter for zero */
>  	if (regval[0])
> -		return IGB_RET_PTP_INVALID;
> +		return 0;
>  
> -	igb_ptp_systim_to_hwtstamp(adapter, skb_hwtstamps(skb),
> -				   le64_to_cpu(regval[1]));
> +	igb_ptp_systim_to_hwtstamp(adapter, &ts, le64_to_cpu(regval[1]));
>  
>  	/* adjust timestamp for the RX latency based on link speed */
>  	if (adapter->hw.mac.type == e1000_i210) {
> @@ -907,10 +902,8 @@ int igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
>  			break;
>  		}
>  	}
> -	skb_hwtstamps(skb)->hwtstamp =
> -		ktime_sub_ns(skb_hwtstamps(skb)->hwtstamp, adjust);
>  
> -	return 0;
> +	return ktime_sub_ns(ts.hwtstamp, adjust);
>  }
>  
>  /**
> -- 
> 2.20.1
> 

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH net v3] igb: Fix XDP with PTP enabled
  2021-04-22 10:11 ` Maciej Fijalkowski
@ 2021-04-23  6:45   ` Kurt Kanzenbach
  2021-04-23 11:51     ` Maciej Fijalkowski
  0 siblings, 1 reply; 4+ messages in thread
From: Kurt Kanzenbach @ 2021-04-23  6:45 UTC (permalink / raw)
  To: Maciej Fijalkowski
  Cc: Jesse Brandeburg, Tony Nguyen, David S. Miller, Jakub Kicinski,
	Alexei Starovoitov, Daniel Borkmann, Jesper Dangaard Brouer,
	John Fastabend, Sven Auhagen, intel-wired-lan, netdev, bpf,
	Ilias Apalodimas, Lorenzo Bianconi, Sebastian Andrzej Siewior,
	Richard Cochran, Alexander Duyck

[-- Attachment #1: Type: text/plain, Size: 2100 bytes --]

On Thu Apr 22 2021, Maciej Fijalkowski wrote:
> On Thu, Apr 22, 2021 at 07:26:17AM +0200, Kurt Kanzenbach wrote:
>> +		/* pull rx packet timestamp if available and valid */
>> +		if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
>> +			timestamp = igb_ptp_rx_pktstamp(rx_ring->q_vector,
>> +							pktbuf);
>> +
>> +			if (timestamp) {
>> +				pkt_offset += IGB_TS_HDR_LEN;
>> +				size -= IGB_TS_HDR_LEN;
>> +			}
>> +		}
>
> Small nit: since this is a hot path, maybe we could omit the additional
> branch that you're introducing above and make igb_ptp_rx_pktstamp() to
> return either 0 for error cases and IGB_TS_HDR_LEN if timestamp was fine?
> timestamp itself would be passed as an arg.
>
> So:
> 		if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
> 			ts_offset = igb_ptp_rx_pktstamp(rx_ring->q_vector,
> 							pktbuf, &timestamp);
> 			pkt_offset += ts_offset;
> 			size -= ts_offset;
> 		}
>
> Thoughts? I feel like if we see that desc has timestamp enabled then let's
> optimize it for successful case.

Yes, this should work as well. Actually I didn't like the if statement
either. Only one comment: It's not an offset but rather the timestamp
header length. I'd call it 'ts_len'.

>
>>  
>>  		/* retrieve a buffer from the ring */
>>  		if (!skb) {
>> -			unsigned int offset = igb_rx_offset(rx_ring);
>> -			unsigned char *hard_start;
>> +			unsigned char *hard_start = pktbuf - igb_rx_offset(rx_ring);
>> +			unsigned int offset = pkt_offset + igb_rx_offset(rx_ring);
>
> Probably we could do something similar in flavour of:
> https://lore.kernel.org/bpf/20210118151318.12324-10-maciej.fijalkowski@intel.com/
>
> which broke XDP_REDIRECT and got fixed in:
> https://lore.kernel.org/bpf/20210303153928.11764-2-maciej.fijalkowski@intel.com/
>
> You get the idea.

Yes, I do. However, I think such a change doesn't belong in this patch,
which is a bugfix for XDP. It looks like an optimization. Should I split
it into two patches and rather target net-next instead of net?

Thanks for your review.

Thanks,
Kurt

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^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH net v3] igb: Fix XDP with PTP enabled
  2021-04-23  6:45   ` Kurt Kanzenbach
@ 2021-04-23 11:51     ` Maciej Fijalkowski
  0 siblings, 0 replies; 4+ messages in thread
From: Maciej Fijalkowski @ 2021-04-23 11:51 UTC (permalink / raw)
  To: Kurt Kanzenbach
  Cc: Jesse Brandeburg, Tony Nguyen, David S. Miller, Jakub Kicinski,
	Alexei Starovoitov, Daniel Borkmann, Jesper Dangaard Brouer,
	John Fastabend, Sven Auhagen, intel-wired-lan, netdev, bpf,
	Ilias Apalodimas, Lorenzo Bianconi, Sebastian Andrzej Siewior,
	Richard Cochran, Alexander Duyck

On Fri, Apr 23, 2021 at 08:45:52AM +0200, Kurt Kanzenbach wrote:
> On Thu Apr 22 2021, Maciej Fijalkowski wrote:
> > On Thu, Apr 22, 2021 at 07:26:17AM +0200, Kurt Kanzenbach wrote:
> >> +		/* pull rx packet timestamp if available and valid */
> >> +		if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
> >> +			timestamp = igb_ptp_rx_pktstamp(rx_ring->q_vector,
> >> +							pktbuf);
> >> +
> >> +			if (timestamp) {
> >> +				pkt_offset += IGB_TS_HDR_LEN;
> >> +				size -= IGB_TS_HDR_LEN;
> >> +			}
> >> +		}
> >
> > Small nit: since this is a hot path, maybe we could omit the additional
> > branch that you're introducing above and make igb_ptp_rx_pktstamp() to
> > return either 0 for error cases and IGB_TS_HDR_LEN if timestamp was fine?
> > timestamp itself would be passed as an arg.
> >
> > So:
> > 		if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
> > 			ts_offset = igb_ptp_rx_pktstamp(rx_ring->q_vector,
> > 							pktbuf, &timestamp);
> > 			pkt_offset += ts_offset;
> > 			size -= ts_offset;
> > 		}
> >
> > Thoughts? I feel like if we see that desc has timestamp enabled then let's
> > optimize it for successful case.
> 
> Yes, this should work as well. Actually I didn't like the if statement
> either. Only one comment: It's not an offset but rather the timestamp
> header length. I'd call it 'ts_len'.

Right, sorry.

> 
> >
> >>  
> >>  		/* retrieve a buffer from the ring */
> >>  		if (!skb) {
> >> -			unsigned int offset = igb_rx_offset(rx_ring);
> >> -			unsigned char *hard_start;
> >> +			unsigned char *hard_start = pktbuf - igb_rx_offset(rx_ring);
> >> +			unsigned int offset = pkt_offset + igb_rx_offset(rx_ring);
> >
> > Probably we could do something similar in flavour of:
> > https://lore.kernel.org/bpf/20210118151318.12324-10-maciej.fijalkowski@intel.com/
> >
> > which broke XDP_REDIRECT and got fixed in:
> > https://lore.kernel.org/bpf/20210303153928.11764-2-maciej.fijalkowski@intel.com/
> >
> > You get the idea.
> 
> Yes, I do. However, I think such a change doesn't belong in this patch,
> which is a bugfix for XDP. It looks like an optimization. Should I split
> it into two patches and rather target net-next instead of net?

This was just a heads up from my side as it caught my eye. For sure it's
out of the scope of that patch, but would be good to have a follow up on
that.

> 
> Thanks for your review.
> 
> Thanks,
> Kurt



^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-04-23 12:06 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-04-22  5:26 [PATCH net v3] igb: Fix XDP with PTP enabled Kurt Kanzenbach
2021-04-22 10:11 ` Maciej Fijalkowski
2021-04-23  6:45   ` Kurt Kanzenbach
2021-04-23 11:51     ` Maciej Fijalkowski

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