diff mbox series

[V2,net,2/4] net: fec: recycle pages for transmitted XDP frames

Message ID 20230706081012.2278063-3-wei.fang@nxp.com (mailing list archive)
State Accepted
Commit 20f797399035a8052dbd7297fdbe094079a9482e
Delegated to: Netdev Maintainers
Headers show
Series net: fec: fix some issues of ndo_xdp_xmit() | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1341 this patch: 1341
netdev/cc_maintainers success CCed 14 of 14 maintainers
netdev/build_clang success Errors and warnings before: 1364 this patch: 1364
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 1364 this patch: 1364
netdev/checkpatch warning WARNING: line length of 83 exceeds 80 columns WARNING: line length of 85 exceeds 80 columns WARNING: line length of 87 exceeds 80 columns WARNING: line length of 88 exceeds 80 columns WARNING: line length of 93 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Wei Fang July 6, 2023, 8:10 a.m. UTC 
From: Wei Fang <wei.fang@nxp.com>

Once the XDP frames have been successfully transmitted through the
ndo_xdp_xmit() interface, it's the driver responsibility to free
the frames so that the page_pool can recycle the pages and reuse
them. However, this action is not implemented in the fec driver.
This leads to a user-visible problem that the console will print
the following warning log.

[  157.568851] page_pool_release_retry() stalled pool shutdown 1389 inflight 60 sec
[  217.983446] page_pool_release_retry() stalled pool shutdown 1389 inflight 120 sec
[  278.399006] page_pool_release_retry() stalled pool shutdown 1389 inflight 181 sec
[  338.812885] page_pool_release_retry() stalled pool shutdown 1389 inflight 241 sec
[  399.226946] page_pool_release_retry() stalled pool shutdown 1389 inflight 302 sec

Therefore, to solve this issue, we free XDP frames via xdp_return_frame()
while cleaning the tx BD ring.

Fixes: 6d6b39f180b8 ("net: fec: add initial XDP support")
Signed-off-by: Wei Fang <wei.fang@nxp.com>
---
V2 change:
No change.
---
 drivers/net/ethernet/freescale/fec.h      |  15 ++-
 drivers/net/ethernet/freescale/fec_main.c | 148 +++++++++++++++-------
 2 files changed, 115 insertions(+), 48 deletions(-)

Comments

Alexander Lobakin July 6, 2023, 11:59 a.m. UTC | #1 
From: Wei Fang <wei.fang@nxp.com>
Date: Thu,  6 Jul 2023 16:10:10 +0800

> From: Wei Fang <wei.fang@nxp.com>
> 
> Once the XDP frames have been successfully transmitted through the
> ndo_xdp_xmit() interface, it's the driver responsibility to free
> the frames so that the page_pool can recycle the pages and reuse
> them. However, this action is not implemented in the fec driver.
> This leads to a user-visible problem that the console will print
> the following warning log.

[...]

> +				if (txq->tx_buf[i].xdp) {
> +					xdp_return_frame(txq->tx_buf[i].xdp);
> +					txq->tx_buf[i].xdp = NULL;
> +				}
> +
> +				/* restore default tx buffer type: FEC_TXBUF_T_SKB */
> +				txq->tx_buf[i].type = FEC_TXBUF_T_SKB;

Here and in the related places below: maybe set ::type dynamically when
sending to either SKB or XDP instead of setting it only for XDP and then
restoring each time?

>  			}
> +
>  			bdp->cbd_bufaddr = cpu_to_fec32(0);
>  			bdp = fec_enet_get_nextdesc(bdp, &txq->bd);
>  		}
[...]

Thanks,
Olek
Wei Fang July 7, 2023, 1:54 a.m. UTC | #2 
> -----Original Message-----
> From: Alexander Lobakin <aleksander.lobakin@intel.com>
> Sent: 2023年7月6日 19:59
> To: Wei Fang <wei.fang@nxp.com>
> Cc: davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
> pabeni@redhat.com; ast@kernel.org; daniel@iogearbox.net;
> hawk@kernel.org; john.fastabend@gmail.com; Shenwei Wang
> <shenwei.wang@nxp.com>; Clark Wang <xiaoning.wang@nxp.com>;
> netdev@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>;
> linux-kernel@vger.kernel.org; bpf@vger.kernel.org
> Subject: Re: [PATCH V2 net 2/4] net: fec: recycle pages for transmitted XDP
> frames
> 
> From: Wei Fang <wei.fang@nxp.com>
> Date: Thu,  6 Jul 2023 16:10:10 +0800
> 
> > From: Wei Fang <wei.fang@nxp.com>
> >
> > Once the XDP frames have been successfully transmitted through the
> > ndo_xdp_xmit() interface, it's the driver responsibility to free the
> > frames so that the page_pool can recycle the pages and reuse them.
> > However, this action is not implemented in the fec driver.
> > This leads to a user-visible problem that the console will print the
> > following warning log.
> 
> [...]
> 
> > +				if (txq->tx_buf[i].xdp) {
> > +					xdp_return_frame(txq->tx_buf[i].xdp);
> > +					txq->tx_buf[i].xdp = NULL;
> > +				}
> > +
> > +				/* restore default tx buffer type: FEC_TXBUF_T_SKB */
> > +				txq->tx_buf[i].type = FEC_TXBUF_T_SKB;
> 
> Here and in the related places below: maybe set ::type dynamically when
> sending to either SKB or XDP instead of setting it only for XDP and then
> restoring each time?
I also considered this method. but when the skb has frags or needs to be TSO,
only the last tx_buf of the skb needs to store the skb pointer, but all the tx_buf
of the skb needs to set the type explicitly, I think it is a bit mess and not concise.
So I restore the type to default when recycle the BDs. Anyway, it;s just a difference
in implement, if you guys insist it's better to set the type explicitly, I will modify
the patch. Thanks!
> 
> >  			}
> > +
> >  			bdp->cbd_bufaddr = cpu_to_fec32(0);
> >  			bdp = fec_enet_get_nextdesc(bdp, &txq->bd);
> >  		}
> [...]
> 
> Thanks,
> Olek
Alexander Lobakin July 10, 2023, 12:58 p.m. UTC | #3 
From: Wei Fang <wei.fang@nxp.com>
Date: Fri, 7 Jul 2023 01:54:04 +0000

>> -----Original Message-----
>> From: Alexander Lobakin <aleksander.lobakin@intel.com>
>> Sent: 2023年7月6日 19:59
>> To: Wei Fang <wei.fang@nxp.com>
>> Cc: davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
>> pabeni@redhat.com; ast@kernel.org; daniel@iogearbox.net;
>> hawk@kernel.org; john.fastabend@gmail.com; Shenwei Wang
>> <shenwei.wang@nxp.com>; Clark Wang <xiaoning.wang@nxp.com>;
>> netdev@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>;
>> linux-kernel@vger.kernel.org; bpf@vger.kernel.org
>> Subject: Re: [PATCH V2 net 2/4] net: fec: recycle pages for transmitted XDP
>> frames
>>
>> From: Wei Fang <wei.fang@nxp.com>
>> Date: Thu,  6 Jul 2023 16:10:10 +0800
>>
>>> From: Wei Fang <wei.fang@nxp.com>
>>>
>>> Once the XDP frames have been successfully transmitted through the
>>> ndo_xdp_xmit() interface, it's the driver responsibility to free the
>>> frames so that the page_pool can recycle the pages and reuse them.
>>> However, this action is not implemented in the fec driver.
>>> This leads to a user-visible problem that the console will print the
>>> following warning log.
>>
>> [...]
>>
>>> +				if (txq->tx_buf[i].xdp) {
>>> +					xdp_return_frame(txq->tx_buf[i].xdp);
>>> +					txq->tx_buf[i].xdp = NULL;
>>> +				}
>>> +
>>> +				/* restore default tx buffer type: FEC_TXBUF_T_SKB */
>>> +				txq->tx_buf[i].type = FEC_TXBUF_T_SKB;
>>
>> Here and in the related places below: maybe set ::type dynamically when
>> sending to either SKB or XDP instead of setting it only for XDP and then
>> restoring each time?
> I also considered this method. but when the skb has frags or needs to be TSO,
> only the last tx_buf of the skb needs to store the skb pointer, but all the tx_buf
> of the skb needs to set the type explicitly, I think it is a bit mess and not concise.
> So I restore the type to default when recycle the BDs. Anyway, it;s just a difference
> in implement, if you guys insist it's better to set the type explicitly, I will modify
> the patch. Thanks!

Just more of personal preference, no problems. Moreover, your
explanation makes sense to me.

>>
>>>  			}
>>> +
>>>  			bdp->cbd_bufaddr = cpu_to_fec32(0);
>>>  			bdp = fec_enet_get_nextdesc(bdp, &txq->bd);
>>>  		}
>> [...]
>>
>> Thanks,
>> Olek

Thanks,
Olek
diff mbox series

Patch

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index 9939ccafb556..8c0226d061fe 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -544,10 +544,23 @@  enum {
 	XDP_STATS_TOTAL,
 };
 
+enum fec_txbuf_type {
+	FEC_TXBUF_T_SKB,
+	FEC_TXBUF_T_XDP_NDO,
+};
+
+struct fec_tx_buffer {
+	union {
+		struct sk_buff *skb;
+		struct xdp_frame *xdp;
+	};
+	enum fec_txbuf_type type;
+};
+
 struct fec_enet_priv_tx_q {
 	struct bufdesc_prop bd;
 	unsigned char *tx_bounce[TX_RING_SIZE];
-	struct  sk_buff *tx_skbuff[TX_RING_SIZE];
+	struct fec_tx_buffer tx_buf[TX_RING_SIZE];
 
 	unsigned short tx_stop_threshold;
 	unsigned short tx_wake_threshold;
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 9ce0319b33c3..940d3afe1d24 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -397,7 +397,7 @@  static void fec_dump(struct net_device *ndev)
 			fec16_to_cpu(bdp->cbd_sc),
 			fec32_to_cpu(bdp->cbd_bufaddr),
 			fec16_to_cpu(bdp->cbd_datlen),
-			txq->tx_skbuff[index]);
+			txq->tx_buf[index].skb);
 		bdp = fec_enet_get_nextdesc(bdp, &txq->bd);
 		index++;
 	} while (bdp != txq->bd.base);
@@ -654,7 +654,7 @@  static int fec_enet_txq_submit_skb(struct fec_enet_priv_tx_q *txq,
 
 	index = fec_enet_get_bd_index(last_bdp, &txq->bd);
 	/* Save skb pointer */
-	txq->tx_skbuff[index] = skb;
+	txq->tx_buf[index].skb = skb;
 
 	/* Make sure the updates to rest of the descriptor are performed before
 	 * transferring ownership.
@@ -672,9 +672,7 @@  static int fec_enet_txq_submit_skb(struct fec_enet_priv_tx_q *txq,
 
 	skb_tx_timestamp(skb);
 
-	/* Make sure the update to bdp and tx_skbuff are performed before
-	 * txq->bd.cur.
-	 */
+	/* Make sure the update to bdp is performed before txq->bd.cur. */
 	wmb();
 	txq->bd.cur = bdp;
 
@@ -862,7 +860,7 @@  static int fec_enet_txq_submit_tso(struct fec_enet_priv_tx_q *txq,
 	}
 
 	/* Save skb pointer */
-	txq->tx_skbuff[index] = skb;
+	txq->tx_buf[index].skb = skb;
 
 	skb_tx_timestamp(skb);
 	txq->bd.cur = bdp;
@@ -952,16 +950,33 @@  static void fec_enet_bd_init(struct net_device *dev)
 		for (i = 0; i < txq->bd.ring_size; i++) {
 			/* Initialize the BD for every fragment in the page. */
 			bdp->cbd_sc = cpu_to_fec16(0);
-			if (bdp->cbd_bufaddr &&
-			    !IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr)))
-				dma_unmap_single(&fep->pdev->dev,
-						 fec32_to_cpu(bdp->cbd_bufaddr),
-						 fec16_to_cpu(bdp->cbd_datlen),
-						 DMA_TO_DEVICE);
-			if (txq->tx_skbuff[i]) {
-				dev_kfree_skb_any(txq->tx_skbuff[i]);
-				txq->tx_skbuff[i] = NULL;
+			if (txq->tx_buf[i].type == FEC_TXBUF_T_SKB) {
+				if (bdp->cbd_bufaddr &&
+				    !IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr)))
+					dma_unmap_single(&fep->pdev->dev,
+							 fec32_to_cpu(bdp->cbd_bufaddr),
+							 fec16_to_cpu(bdp->cbd_datlen),
+							 DMA_TO_DEVICE);
+				if (txq->tx_buf[i].skb) {
+					dev_kfree_skb_any(txq->tx_buf[i].skb);
+					txq->tx_buf[i].skb = NULL;
+				}
+			} else {
+				if (bdp->cbd_bufaddr)
+					dma_unmap_single(&fep->pdev->dev,
+							 fec32_to_cpu(bdp->cbd_bufaddr),
+							 fec16_to_cpu(bdp->cbd_datlen),
+							 DMA_TO_DEVICE);
+
+				if (txq->tx_buf[i].xdp) {
+					xdp_return_frame(txq->tx_buf[i].xdp);
+					txq->tx_buf[i].xdp = NULL;
+				}
+
+				/* restore default tx buffer type: FEC_TXBUF_T_SKB */
+				txq->tx_buf[i].type = FEC_TXBUF_T_SKB;
 			}
+
 			bdp->cbd_bufaddr = cpu_to_fec32(0);
 			bdp = fec_enet_get_nextdesc(bdp, &txq->bd);
 		}
@@ -1360,6 +1375,7 @@  static void
 fec_enet_tx_queue(struct net_device *ndev, u16 queue_id)
 {
 	struct	fec_enet_private *fep;
+	struct xdp_frame *xdpf;
 	struct bufdesc *bdp;
 	unsigned short status;
 	struct	sk_buff	*skb;
@@ -1387,16 +1403,31 @@  fec_enet_tx_queue(struct net_device *ndev, u16 queue_id)
 
 		index = fec_enet_get_bd_index(bdp, &txq->bd);
 
-		skb = txq->tx_skbuff[index];
-		txq->tx_skbuff[index] = NULL;
-		if (!IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr)))
-			dma_unmap_single(&fep->pdev->dev,
-					 fec32_to_cpu(bdp->cbd_bufaddr),
-					 fec16_to_cpu(bdp->cbd_datlen),
-					 DMA_TO_DEVICE);
-		bdp->cbd_bufaddr = cpu_to_fec32(0);
-		if (!skb)
-			goto skb_done;
+		if (txq->tx_buf[index].type == FEC_TXBUF_T_SKB) {
+			skb = txq->tx_buf[index].skb;
+			txq->tx_buf[index].skb = NULL;
+			if (bdp->cbd_bufaddr &&
+			    !IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr)))
+				dma_unmap_single(&fep->pdev->dev,
+						 fec32_to_cpu(bdp->cbd_bufaddr),
+						 fec16_to_cpu(bdp->cbd_datlen),
+						 DMA_TO_DEVICE);
+			bdp->cbd_bufaddr = cpu_to_fec32(0);
+			if (!skb)
+				goto tx_buf_done;
+		} else {
+			xdpf = txq->tx_buf[index].xdp;
+			if (bdp->cbd_bufaddr)
+				dma_unmap_single(&fep->pdev->dev,
+						 fec32_to_cpu(bdp->cbd_bufaddr),
+						 fec16_to_cpu(bdp->cbd_datlen),
+						 DMA_TO_DEVICE);
+			bdp->cbd_bufaddr = cpu_to_fec32(0);
+			if (!xdpf) {
+				txq->tx_buf[index].type = FEC_TXBUF_T_SKB;
+				goto tx_buf_done;
+			}
+		}
 
 		/* Check for errors. */
 		if (status & (BD_ENET_TX_HB | BD_ENET_TX_LC |
@@ -1415,21 +1446,11 @@  fec_enet_tx_queue(struct net_device *ndev, u16 queue_id)
 				ndev->stats.tx_carrier_errors++;
 		} else {
 			ndev->stats.tx_packets++;
-			ndev->stats.tx_bytes += skb->len;
-		}
 
-		/* NOTE: SKBTX_IN_PROGRESS being set does not imply it's we who
-		 * are to time stamp the packet, so we still need to check time
-		 * stamping enabled flag.
-		 */
-		if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS &&
-			     fep->hwts_tx_en) &&
-		    fep->bufdesc_ex) {
-			struct skb_shared_hwtstamps shhwtstamps;
-			struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;
-
-			fec_enet_hwtstamp(fep, fec32_to_cpu(ebdp->ts), &shhwtstamps);
-			skb_tstamp_tx(skb, &shhwtstamps);
+			if (txq->tx_buf[index].type == FEC_TXBUF_T_SKB)
+				ndev->stats.tx_bytes += skb->len;
+			else
+				ndev->stats.tx_bytes += xdpf->len;
 		}
 
 		/* Deferred means some collisions occurred during transmit,
@@ -1438,10 +1459,32 @@  fec_enet_tx_queue(struct net_device *ndev, u16 queue_id)
 		if (status & BD_ENET_TX_DEF)
 			ndev->stats.collisions++;
 
-		/* Free the sk buffer associated with this last transmit */
-		dev_kfree_skb_any(skb);
-skb_done:
-		/* Make sure the update to bdp and tx_skbuff are performed
+		if (txq->tx_buf[index].type == FEC_TXBUF_T_SKB) {
+			/* NOTE: SKBTX_IN_PROGRESS being set does not imply it's we who
+			 * are to time stamp the packet, so we still need to check time
+			 * stamping enabled flag.
+			 */
+			if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS &&
+				     fep->hwts_tx_en) && fep->bufdesc_ex) {
+				struct skb_shared_hwtstamps shhwtstamps;
+				struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;
+
+				fec_enet_hwtstamp(fep, fec32_to_cpu(ebdp->ts), &shhwtstamps);
+				skb_tstamp_tx(skb, &shhwtstamps);
+			}
+
+			/* Free the sk buffer associated with this last transmit */
+			dev_kfree_skb_any(skb);
+		} else {
+			xdp_return_frame(xdpf);
+
+			txq->tx_buf[index].xdp = NULL;
+			/* restore default tx buffer type: FEC_TXBUF_T_SKB */
+			txq->tx_buf[index].type = FEC_TXBUF_T_SKB;
+		}
+
+tx_buf_done:
+		/* Make sure the update to bdp and tx_buf are performed
 		 * before dirty_tx
 		 */
 		wmb();
@@ -3249,9 +3292,19 @@  static void fec_enet_free_buffers(struct net_device *ndev)
 		for (i = 0; i < txq->bd.ring_size; i++) {
 			kfree(txq->tx_bounce[i]);
 			txq->tx_bounce[i] = NULL;
-			skb = txq->tx_skbuff[i];
-			txq->tx_skbuff[i] = NULL;
-			dev_kfree_skb(skb);
+
+			if (txq->tx_buf[i].type == FEC_TXBUF_T_SKB) {
+				skb = txq->tx_buf[i].skb;
+				txq->tx_buf[i].skb = NULL;
+				dev_kfree_skb(skb);
+			} else {
+				if (txq->tx_buf[i].xdp) {
+					xdp_return_frame(txq->tx_buf[i].xdp);
+					txq->tx_buf[i].xdp = NULL;
+				}
+
+				txq->tx_buf[i].type = FEC_TXBUF_T_SKB;
+			}
 		}
 	}
 }
@@ -3817,7 +3870,8 @@  static int fec_enet_txq_xmit_frame(struct fec_enet_private *fep,
 		ebdp->cbd_esc = cpu_to_fec32(estatus);
 	}
 
-	txq->tx_skbuff[index] = NULL;
+	txq->tx_buf[index].type = FEC_TXBUF_T_XDP_NDO;
+	txq->tx_buf[index].xdp = frame;
 
 	/* Make sure the updates to rest of the descriptor are performed before
 	 * transferring ownership.