Re: [PATCH RESEND net-next 1/2] dpaa2-eth: send a scatter-gather FD instead of realloc-ing

Re: [PATCH RESEND net-next 1/2] dpaa2-eth: send a scatter-gather FD instead of realloc-ing

[Ioana Ciornei]

[Added also the netdev mailing list, I haven't heard of linux-netdev
before but kept it]

On Thu, Dec 10, 2020 at 05:31:56PM +0000, Daniel Thompson wrote:
> Hi Ioana

Hi Daniel,

> 
> On Mon, Jun 29, 2020 at 06:47:11PM +0000, Ioana Ciornei wrote:
> > Instead of realloc-ing the skb on the Tx path when the provided headroom
> > is smaller than the HW requirements, create a Scatter/Gather frame
> > descriptor with only one entry.
> > 
> > Remove the '[drv] tx realloc frames' counter exposed previously through
> > ethtool since it is no longer used.
> > 
> > Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> > ---
> 
> I've been chasing down a networking regression on my LX2160A board
> (Honeycomb LX2K based on CEx7 LX2160A COM) that first appeared in v5.9.
> 
> It makes the board unreliable opening outbound connections meaning
> things like `apt update` or `git fetch` often can't open the connection.
> It does not happen all the time but is sufficient to make the boards
> built-in networking useless for workstation use.
> 
> The problem is strongly linked to warnings in the logs so I used the
> warnings to bisect down to locate the cause of the regression and it
> pinpointed this patch. I have confirmed that in both v5.9 and v5.10-rc7
> that reverting this patch (and fixing up the merge issues) fixes the
> regression and the warnings stop appearing.
> 
> A typical example of the warning is below (io-pgtable-arm.c:281 is an
> error path that I guess would cause dma_map_page_attrs() to return
> an error):
> 
> [  714.464927] WARNING: CPU: 13 PID: 0 at
> drivers/iommu/io-pgtable-arm.c:281 __arm_lpae_map+0x2d4/0x30c
> [  714.464930] Modules linked in: snd_seq_dummy(E) snd_hrtimer(E)
> snd_seq(E) snd_seq_device(E) snd_timer(E) snd(E) soundcore(E) bridge(E)
> stp(E) llc(E) rfkill(E) caam_jr(E) crypto_engine(E) rng_core(E)
> joydev(E) evdev(E) dpaa2_caam(E) caamhash_desc(E) caamalg_desc(E)
> authenc(E) libdes(E) dpaa2_console(E) ofpart(E) caam(E) sg(E) error(E)
> lm90(E) at24(E) spi_nor(E) mtd(E) sbsa_gwdt(E) qoriq_thermal(E)
> layerscape_edac_mod(E) qoriq_cpufreq(E) drm(E) fuse(E) configfs(E)
> ip_tables(E) x_tables(E) autofs4(E) ext4(E) crc32c_generic(E) crc16(E)
> mbcache(E) jbd2(E) hid_generic(E) usbhid(E) hid(E) dm_crypt(E) dm_mod(E)
> sd_mod(E) fsl_dpaa2_ptp(E) ptp_qoriq(E) fsl_dpaa2_eth(E)
> xhci_plat_hcd(E) xhci_hcd(E) usbcore(E) aes_ce_blk(E) crypto_simd(E)
> cryptd(E) aes_ce_cipher(E) ghash_ce(E) gf128mul(E) at803x(E) libaes(E)
> fsl_mc_dpio(E) pcs_lynx(E) rtc_pcf2127(E) sha2_ce(E) phylink(E)
> xgmac_mdio(E) regmap_spi(E) of_mdio(E) sha256_arm64(E)
> i2c_mux_pca954x(E) fixed_phy(E) i2c_mux(E) sha1_ce(E) ptp(E) libphy(E)
> [  714.465131]  pps_core(E) ahci_qoriq(E) libahci_platform(E) nvme(E)
> libahci(E) nvme_core(E) t10_pi(E) libata(E) crc_t10dif(E)
> crct10dif_generic(E) crct10dif_common(E) dwc3(E) scsi_mod(E) udc_core(E)
> roles(E) ulpi(E) sdhci_of_esdhc(E) sdhci_pltfm(E) sdhci(E)
> spi_nxp_fspi(E) i2c_imx(E) fixed(E)
> [  714.465192] CPU: 13 PID: 0 Comm: swapper/13 Tainted: G        W   E
> 5.10.0-rc7-00001-gba98d13279ca #52
> [  714.465196] Hardware name: SolidRun LX2160A Honeycomb (DT)
> [  714.465202] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
> [  714.465207] pc : __arm_lpae_map+0x2d4/0x30c
> [  714.465211] lr : __arm_lpae_map+0x114/0x30c
> [  714.465215] sp : ffff80001006b340
> [  714.465219] x29: ffff80001006b340 x28: 0000002086538003 
> [  714.465227] x27: 0000000000000a20 x26: 0000000000001000 
> [  714.465236] x25: 0000000000000f44 x24: 00000020adf8d000 
> [  714.465245] x23: 0000000000000001 x22: 0000fffffaeca000 
> [  714.465253] x21: 0000000000000003 x20: ffff19b60d64d200 
> [  714.465261] x19: 00000000000000ca x18: 0000000000000000 
> [  714.465270] x17: 0000000000000000 x16: ffffcccb7cf3ca20 
> [  714.465278] x15: 0000000000000000 x14: 0000000000000000 
> [  714.465286] x13: 0000000000000003 x12: 0000000000000010 
> [  714.465294] x11: 0000000000000000 x10: 0000000000000002 
> [  714.465302] x9 : ffffcccb7d5b6e78 x8 : 00000000000001ff 
> [  714.465311] x7 : ffff19b606538650 x6 : ffff19b606538000 
> [  714.465319] x5 : 0000000000000009 x4 : 0000000000000f44 
> [  714.465327] x3 : 0000000000001000 x2 : 00000020adf8d000 
> [  714.465335] x1 : 0000000000000002 x0 : 0000000000000003 
> [  714.465343] Call trace:
> [  714.465348]  __arm_lpae_map+0x2d4/0x30c
> [  714.465353]  __arm_lpae_map+0x114/0x30c
> [  714.465357]  __arm_lpae_map+0x114/0x30c
> [  714.465362]  __arm_lpae_map+0x114/0x30c
> [  714.465366]  arm_lpae_map+0xf4/0x180
> [  714.465373]  arm_smmu_map+0x4c/0xc0
> [  714.465379]  __iommu_map+0x100/0x2bc
> [  714.465385]  iommu_map_atomic+0x20/0x30
> [  714.465391]  __iommu_dma_map+0xb0/0x110
> [  714.465397]  iommu_dma_map_page+0xb8/0x120
> [  714.465404]  dma_map_page_attrs+0x1a8/0x210
> [  714.465413]  __dpaa2_eth_tx+0x384/0xbd0 [fsl_dpaa2_eth]
> [  714.465421]  dpaa2_eth_tx+0x84/0x134 [fsl_dpaa2_eth]
> [  714.465427]  dev_hard_start_xmit+0x10c/0x2b0
> [  714.465433]  sch_direct_xmit+0x1a0/0x550
> [  714.465438]  __qdisc_run+0x140/0x670
> [  714.465443]  __dev_queue_xmit+0x6c4/0xa74
> [  714.465449]  dev_queue_xmit+0x20/0x2c
> [  714.465463]  br_dev_queue_push_xmit+0xc4/0x1a0 [bridge]
> [  714.465476]  br_forward_finish+0xdc/0xf0 [bridge]
> [  714.465489]  __br_forward+0x160/0x1c0 [bridge]
> [  714.465502]  br_forward+0x13c/0x160 [bridge]
> [  714.465514]  br_dev_xmit+0x228/0x3b0 [bridge]
> [  714.465520]  dev_hard_start_xmit+0x10c/0x2b0
> [  714.465526]  __dev_queue_xmit+0x8f0/0xa74
> [  714.465531]  dev_queue_xmit+0x20/0x2c
> [  714.465538]  arp_xmit+0xc0/0xd0
> [  714.465544]  arp_send_dst+0x78/0xa0
> [  714.465550]  arp_solicit+0xf4/0x260
> [  714.465554]  neigh_probe+0x64/0xb0
> [  714.465560]  neigh_timer_handler+0x2f4/0x400
> [  714.465566]  call_timer_fn+0x3c/0x184
> [  714.465572]  __run_timers.part.0+0x2bc/0x370
> [  714.465578]  run_timer_softirq+0x48/0x80
> [  714.465583]  __do_softirq+0x120/0x36c
> [  714.465589]  irq_exit+0xac/0x100
> [  714.465596]  __handle_domain_irq+0x8c/0xf0
> [  714.465600]  gic_handle_irq+0xcc/0x14c
> [  714.465605]  el1_irq+0xc4/0x180
> [  714.465610]  arch_cpu_idle+0x18/0x30
> [  714.465617]  default_idle_call+0x4c/0x180
> [  714.465623]  do_idle+0x238/0x2b0
> [  714.465629]  cpu_startup_entry+0x30/0xa0
> [  714.465636]  secondary_start_kernel+0x134/0x180
> [  714.465640] ---[ end trace a84a7f61b559005f ]---
> 
> 
> Given it is the iommu code that is provoking the warning I should
> probably mention that the board I have requires
> arm-smmu.disable_bypass=0 on the kernel command line in order to boot.
> Also if it matters I am running the latest firmware from Solidrun
> which is based on LSDK-20.04.
> 

Hmmm, from what I remember I think I tested this with the smmu bypassed
so that is why I didn't catch it.

> Is there any reason for this code not to be working for LX2160A?

I wouldn't expect this to be LX2160A specific but rather a bug in the
implementation.. sorry.

Let me reproduce it and see if I can get to the bottom of it and I will
get back with some more info.

Ioana

> 
> Daniel.
> 
> 
> PS A few months have gone by so I decided not to trim the patch out
>    of this reply so you don't have to go digging!
> 
> 
> 
> >  .../freescale/dpaa2/dpaa2-eth-debugfs.c       |   7 +-
> >  .../net/ethernet/freescale/dpaa2/dpaa2-eth.c  | 177 +++++++++++++++---
> >  .../net/ethernet/freescale/dpaa2/dpaa2-eth.h  |   9 +-
> >  .../ethernet/freescale/dpaa2/dpaa2-ethtool.c  |   1 -
> >  4 files changed, 160 insertions(+), 34 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c
> > index 2880ca02d7e7..5cb357c74dec 100644
> > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c
> > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c
> > @@ -19,14 +19,14 @@ static int dpaa2_dbg_cpu_show(struct seq_file *file, void *offset)
> >  	int i;
> >  
> >  	seq_printf(file, "Per-CPU stats for %s\n", priv->net_dev->name);
> > -	seq_printf(file, "%s%16s%16s%16s%16s%16s%16s%16s%16s%16s\n",
> > +	seq_printf(file, "%s%16s%16s%16s%16s%16s%16s%16s%16s\n",
> >  		   "CPU", "Rx", "Rx Err", "Rx SG", "Tx", "Tx Err", "Tx conf",
> > -		   "Tx SG", "Tx realloc", "Enq busy");
> > +		   "Tx SG", "Enq busy");
> >  
> >  	for_each_online_cpu(i) {
> >  		stats = per_cpu_ptr(priv->percpu_stats, i);
> >  		extras = per_cpu_ptr(priv->percpu_extras, i);
> > -		seq_printf(file, "%3d%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu\n",
> > +		seq_printf(file, "%3d%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu\n",
> >  			   i,
> >  			   stats->rx_packets,
> >  			   stats->rx_errors,
> > @@ -35,7 +35,6 @@ static int dpaa2_dbg_cpu_show(struct seq_file *file, void *offset)
> >  			   stats->tx_errors,
> >  			   extras->tx_conf_frames,
> >  			   extras->tx_sg_frames,
> > -			   extras->tx_reallocs,
> >  			   extras->tx_portal_busy);
> >  	}
> >  
> > diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > index 712bbfdbe7d7..4a264b75c035 100644
> > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > @@ -685,6 +685,86 @@ static int build_sg_fd(struct dpaa2_eth_priv *priv,
> >  	return err;
> >  }
> >  
> > +/* Create a SG frame descriptor based on a linear skb.
> > + *
> > + * This function is used on the Tx path when the skb headroom is not large
> > + * enough for the HW requirements, thus instead of realloc-ing the skb we
> > + * create a SG frame descriptor with only one entry.
> > + */
> > +static int build_sg_fd_single_buf(struct dpaa2_eth_priv *priv,
> > +				  struct sk_buff *skb,
> > +				  struct dpaa2_fd *fd)
> > +{
> > +	struct device *dev = priv->net_dev->dev.parent;
> > +	struct dpaa2_eth_sgt_cache *sgt_cache;
> > +	struct dpaa2_sg_entry *sgt;
> > +	struct dpaa2_eth_swa *swa;
> > +	dma_addr_t addr, sgt_addr;
> > +	void *sgt_buf = NULL;
> > +	int sgt_buf_size;
> > +	int err;
> > +
> > +	/* Prepare the HW SGT structure */
> > +	sgt_cache = this_cpu_ptr(priv->sgt_cache);
> > +	sgt_buf_size = priv->tx_data_offset + sizeof(struct dpaa2_sg_entry);
> > +
> > +	if (sgt_cache->count == 0)
> > +		sgt_buf = kzalloc(sgt_buf_size + DPAA2_ETH_TX_BUF_ALIGN,
> > +				  GFP_ATOMIC);
> > +	else
> > +		sgt_buf = sgt_cache->buf[--sgt_cache->count];
> > +	if (unlikely(!sgt_buf))
> > +		return -ENOMEM;
> > +
> > +	sgt_buf = PTR_ALIGN(sgt_buf, DPAA2_ETH_TX_BUF_ALIGN);
> > +	sgt = (struct dpaa2_sg_entry *)(sgt_buf + priv->tx_data_offset);
> > +
> > +	addr = dma_map_single(dev, skb->data, skb->len, DMA_BIDIRECTIONAL);
> > +	if (unlikely(dma_mapping_error(dev, addr))) {
> > +		err = -ENOMEM;
> > +		goto data_map_failed;
> > +	}
> > +
> > +	/* Fill in the HW SGT structure */
> > +	dpaa2_sg_set_addr(sgt, addr);
> > +	dpaa2_sg_set_len(sgt, skb->len);
> > +	dpaa2_sg_set_final(sgt, true);
> > +
> > +	/* Store the skb backpointer in the SGT buffer */
> > +	swa = (struct dpaa2_eth_swa *)sgt_buf;
> > +	swa->type = DPAA2_ETH_SWA_SINGLE;
> > +	swa->single.skb = skb;
> > +	swa->sg.sgt_size = sgt_buf_size;
> > +
> > +	/* Separately map the SGT buffer */
> > +	sgt_addr = dma_map_single(dev, sgt_buf, sgt_buf_size, DMA_BIDIRECTIONAL);
> > +	if (unlikely(dma_mapping_error(dev, sgt_addr))) {
> > +		err = -ENOMEM;
> > +		goto sgt_map_failed;
> > +	}
> > +
> > +	dpaa2_fd_set_offset(fd, priv->tx_data_offset);
> > +	dpaa2_fd_set_format(fd, dpaa2_fd_sg);
> > +	dpaa2_fd_set_addr(fd, sgt_addr);
> > +	dpaa2_fd_set_len(fd, skb->len);
> > +	dpaa2_fd_set_ctrl(fd, FD_CTRL_PTA);
> > +
> > +	if (priv->tx_tstamp && skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)
> > +		enable_tx_tstamp(fd, sgt_buf);
> > +
> > +	return 0;
> > +
> > +sgt_map_failed:
> > +	dma_unmap_single(dev, addr, skb->len, DMA_BIDIRECTIONAL);
> > +data_map_failed:
> > +	if (sgt_cache->count >= DPAA2_ETH_SGT_CACHE_SIZE)
> > +		kfree(sgt_buf);
> > +	else
> > +		sgt_cache->buf[sgt_cache->count++] = sgt_buf;
> > +
> > +	return err;
> > +}
> > +
> >  /* Create a frame descriptor based on a linear skb */
> >  static int build_single_fd(struct dpaa2_eth_priv *priv,
> >  			   struct sk_buff *skb,
> > @@ -743,13 +823,16 @@ static void free_tx_fd(const struct dpaa2_eth_priv *priv,
> >  		       const struct dpaa2_fd *fd, bool in_napi)
> >  {
> >  	struct device *dev = priv->net_dev->dev.parent;
> > -	dma_addr_t fd_addr;
> > +	dma_addr_t fd_addr, sg_addr;
> >  	struct sk_buff *skb = NULL;
> >  	unsigned char *buffer_start;
> >  	struct dpaa2_eth_swa *swa;
> >  	u8 fd_format = dpaa2_fd_get_format(fd);
> >  	u32 fd_len = dpaa2_fd_get_len(fd);
> >  
> > +	struct dpaa2_eth_sgt_cache *sgt_cache;
> > +	struct dpaa2_sg_entry *sgt;
> > +
> >  	fd_addr = dpaa2_fd_get_addr(fd);
> >  	buffer_start = dpaa2_iova_to_virt(priv->iommu_domain, fd_addr);
> >  	swa = (struct dpaa2_eth_swa *)buffer_start;
> > @@ -769,16 +852,29 @@ static void free_tx_fd(const struct dpaa2_eth_priv *priv,
> >  					 DMA_BIDIRECTIONAL);
> >  		}
> >  	} else if (fd_format == dpaa2_fd_sg) {
> > -		skb = swa->sg.skb;
> > +		if (swa->type == DPAA2_ETH_SWA_SG) {
> > +			skb = swa->sg.skb;
> > +
> > +			/* Unmap the scatterlist */
> > +			dma_unmap_sg(dev, swa->sg.scl, swa->sg.num_sg,
> > +				     DMA_BIDIRECTIONAL);
> > +			kfree(swa->sg.scl);
> >  
> > -		/* Unmap the scatterlist */
> > -		dma_unmap_sg(dev, swa->sg.scl, swa->sg.num_sg,
> > -			     DMA_BIDIRECTIONAL);
> > -		kfree(swa->sg.scl);
> > +			/* Unmap the SGT buffer */
> > +			dma_unmap_single(dev, fd_addr, swa->sg.sgt_size,
> > +					 DMA_BIDIRECTIONAL);
> > +		} else {
> > +			skb = swa->single.skb;
> >  
> > -		/* Unmap the SGT buffer */
> > -		dma_unmap_single(dev, fd_addr, swa->sg.sgt_size,
> > -				 DMA_BIDIRECTIONAL);
> > +			/* Unmap the SGT Buffer */
> > +			dma_unmap_single(dev, fd_addr, swa->single.sgt_size,
> > +					 DMA_BIDIRECTIONAL);
> > +
> > +			sgt = (struct dpaa2_sg_entry *)(buffer_start +
> > +							priv->tx_data_offset);
> > +			sg_addr = dpaa2_sg_get_addr(sgt);
> > +			dma_unmap_single(dev, sg_addr, skb->len, DMA_BIDIRECTIONAL);
> > +		}
> >  	} else {
> >  		netdev_dbg(priv->net_dev, "Invalid FD format\n");
> >  		return;
> > @@ -808,8 +904,17 @@ static void free_tx_fd(const struct dpaa2_eth_priv *priv,
> >  	}
> >  
> >  	/* Free SGT buffer allocated on tx */
> > -	if (fd_format != dpaa2_fd_single)
> > -		skb_free_frag(buffer_start);
> > +	if (fd_format != dpaa2_fd_single) {
> > +		sgt_cache = this_cpu_ptr(priv->sgt_cache);
> > +		if (swa->type == DPAA2_ETH_SWA_SG) {
> > +			skb_free_frag(buffer_start);
> > +		} else {
> > +			if (sgt_cache->count >= DPAA2_ETH_SGT_CACHE_SIZE)
> > +				kfree(buffer_start);
> > +			else
> > +				sgt_cache->buf[sgt_cache->count++] = buffer_start;
> > +		}
> > +	}
> >  
> >  	/* Move on with skb release */
> >  	napi_consume_skb(skb, in_napi);
> > @@ -833,22 +938,6 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
> >  	percpu_extras = this_cpu_ptr(priv->percpu_extras);
> >  
> >  	needed_headroom = dpaa2_eth_needed_headroom(priv, skb);
> > -	if (skb_headroom(skb) < needed_headroom) {
> > -		struct sk_buff *ns;
> > -
> > -		ns = skb_realloc_headroom(skb, needed_headroom);
> > -		if (unlikely(!ns)) {
> > -			percpu_stats->tx_dropped++;
> > -			goto err_alloc_headroom;
> > -		}
> > -		percpu_extras->tx_reallocs++;
> > -
> > -		if (skb->sk)
> > -			skb_set_owner_w(ns, skb->sk);
> > -
> > -		dev_kfree_skb(skb);
> > -		skb = ns;
> > -	}
> >  
> >  	/* We'll be holding a back-reference to the skb until Tx Confirmation;
> >  	 * we don't want that overwritten by a concurrent Tx with a cloned skb.
> > @@ -867,6 +956,10 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
> >  		err = build_sg_fd(priv, skb, &fd);
> >  		percpu_extras->tx_sg_frames++;
> >  		percpu_extras->tx_sg_bytes += skb->len;
> > +	} else if (skb_headroom(skb) < needed_headroom) {
> > +		err = build_sg_fd_single_buf(priv, skb, &fd);
> > +		percpu_extras->tx_sg_frames++;
> > +		percpu_extras->tx_sg_bytes += skb->len;
> >  	} else {
> >  		err = build_single_fd(priv, skb, &fd);
> >  	}
> > @@ -924,7 +1017,6 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
> >  	return NETDEV_TX_OK;
> >  
> >  err_build_fd:
> > -err_alloc_headroom:
> >  	dev_kfree_skb(skb);
> >  
> >  	return NETDEV_TX_OK;
> > @@ -1161,6 +1253,22 @@ static int refill_pool(struct dpaa2_eth_priv *priv,
> >  	return 0;
> >  }
> >  
> > +static void dpaa2_eth_sgt_cache_drain(struct dpaa2_eth_priv *priv)
> > +{
> > +	struct dpaa2_eth_sgt_cache *sgt_cache;
> > +	u16 count;
> > +	int k, i;
> > +
> > +	for_each_online_cpu(k) {
> > +		sgt_cache = per_cpu_ptr(priv->sgt_cache, k);
> > +		count = sgt_cache->count;
> > +
> > +		for (i = 0; i < count; i++)
> > +			kfree(sgt_cache->buf[i]);
> > +		sgt_cache->count = 0;
> > +	}
> > +}
> > +
> >  static int pull_channel(struct dpaa2_eth_channel *ch)
> >  {
> >  	int err;
> > @@ -1562,6 +1670,9 @@ static int dpaa2_eth_stop(struct net_device *net_dev)
> >  	/* Empty the buffer pool */
> >  	drain_pool(priv);
> >  
> > +	/* Empty the Scatter-Gather Buffer cache */
> > +	dpaa2_eth_sgt_cache_drain(priv);
> > +
> >  	return 0;
> >  }
> >  
> > @@ -3846,6 +3957,13 @@ static int dpaa2_eth_probe(struct fsl_mc_device *dpni_dev)
> >  		goto err_alloc_percpu_extras;
> >  	}
> >  
> > +	priv->sgt_cache = alloc_percpu(*priv->sgt_cache);
> > +	if (!priv->sgt_cache) {
> > +		dev_err(dev, "alloc_percpu(sgt_cache) failed\n");
> > +		err = -ENOMEM;
> > +		goto err_alloc_sgt_cache;
> > +	}
> > +
> >  	err = netdev_init(net_dev);
> >  	if (err)
> >  		goto err_netdev_init;
> > @@ -3914,6 +4032,8 @@ static int dpaa2_eth_probe(struct fsl_mc_device *dpni_dev)
> >  err_alloc_rings:
> >  err_csum:
> >  err_netdev_init:
> > +	free_percpu(priv->sgt_cache);
> > +err_alloc_sgt_cache:
> >  	free_percpu(priv->percpu_extras);
> >  err_alloc_percpu_extras:
> >  	free_percpu(priv->percpu_stats);
> > @@ -3959,6 +4079,7 @@ static int dpaa2_eth_remove(struct fsl_mc_device *ls_dev)
> >  		fsl_mc_free_irqs(ls_dev);
> >  
> >  	free_rings(priv);
> > +	free_percpu(priv->sgt_cache);
> >  	free_percpu(priv->percpu_stats);
> >  	free_percpu(priv->percpu_extras);
> >  
> > diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
> > index 2d7ada0f0dbd..9e4ceb92f240 100644
> > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
> > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
> > @@ -125,6 +125,7 @@ struct dpaa2_eth_swa {
> >  	union {
> >  		struct {
> >  			struct sk_buff *skb;
> > +			int sgt_size;
> >  		} single;
> >  		struct {
> >  			struct sk_buff *skb;
> > @@ -282,7 +283,6 @@ struct dpaa2_eth_drv_stats {
> >  	__u64	tx_conf_bytes;
> >  	__u64	tx_sg_frames;
> >  	__u64	tx_sg_bytes;
> > -	__u64	tx_reallocs;
> >  	__u64	rx_sg_frames;
> >  	__u64	rx_sg_bytes;
> >  	/* Enqueues retried due to portal busy */
> > @@ -395,6 +395,12 @@ struct dpaa2_eth_cls_rule {
> >  	u8 in_use;
> >  };
> >  
> > +#define DPAA2_ETH_SGT_CACHE_SIZE	256
> > +struct dpaa2_eth_sgt_cache {
> > +	void *buf[DPAA2_ETH_SGT_CACHE_SIZE];
> > +	u16 count;
> > +};
> > +
> >  /* Driver private data */
> >  struct dpaa2_eth_priv {
> >  	struct net_device *net_dev;
> > @@ -409,6 +415,7 @@ struct dpaa2_eth_priv {
> >  
> >  	u8 num_channels;
> >  	struct dpaa2_eth_channel *channel[DPAA2_ETH_MAX_DPCONS];
> > +	struct dpaa2_eth_sgt_cache __percpu *sgt_cache;
> >  
> >  	struct dpni_attr dpni_attrs;
> >  	u16 dpni_ver_major;
> > diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
> > index e88269fe3de7..c4cbbcaa9a3f 100644
> > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
> > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
> > @@ -43,7 +43,6 @@ static char dpaa2_ethtool_extras[][ETH_GSTRING_LEN] = {
> >  	"[drv] tx conf bytes",
> >  	"[drv] tx sg frames",
> >  	"[drv] tx sg bytes",
> > -	"[drv] tx realloc frames",
> >  	"[drv] rx sg frames",
> >  	"[drv] rx sg bytes",
> >  	"[drv] enqueue portal busy",
> > -- 
> > 2.25.1

Re: [PATCH RESEND net-next 1/2] dpaa2-eth: send a scatter-gather FD instead of realloc-ing

[Jon Nettleton]

On Thu, Dec 10, 2020 at 7:08 PM Ioana Ciornei <ioana.ciornei@nxp.com> wrote:
>
> [Added also the netdev mailing list, I haven't heard of linux-netdev
> before but kept it]
>
> On Thu, Dec 10, 2020 at 05:31:56PM +0000, Daniel Thompson wrote:
> > Hi Ioana
>
> Hi Daniel,
>
> >
> > On Mon, Jun 29, 2020 at 06:47:11PM +0000, Ioana Ciornei wrote:
> > > Instead of realloc-ing the skb on the Tx path when the provided headroom
> > > is smaller than the HW requirements, create a Scatter/Gather frame
> > > descriptor with only one entry.
> > >
> > > Remove the '[drv] tx realloc frames' counter exposed previously through
> > > ethtool since it is no longer used.
> > >
> > > Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> > > ---
> >
> > I've been chasing down a networking regression on my LX2160A board
> > (Honeycomb LX2K based on CEx7 LX2160A COM) that first appeared in v5.9.
> >
> > It makes the board unreliable opening outbound connections meaning
> > things like `apt update` or `git fetch` often can't open the connection.
> > It does not happen all the time but is sufficient to make the boards
> > built-in networking useless for workstation use.
> >
> > The problem is strongly linked to warnings in the logs so I used the
> > warnings to bisect down to locate the cause of the regression and it
> > pinpointed this patch. I have confirmed that in both v5.9 and v5.10-rc7
> > that reverting this patch (and fixing up the merge issues) fixes the
> > regression and the warnings stop appearing.
> >
> > A typical example of the warning is below (io-pgtable-arm.c:281 is an
> > error path that I guess would cause dma_map_page_attrs() to return
> > an error):
> >
> > [  714.464927] WARNING: CPU: 13 PID: 0 at
> > drivers/iommu/io-pgtable-arm.c:281 __arm_lpae_map+0x2d4/0x30c
> > [  714.464930] Modules linked in: snd_seq_dummy(E) snd_hrtimer(E)
> > snd_seq(E) snd_seq_device(E) snd_timer(E) snd(E) soundcore(E) bridge(E)
> > stp(E) llc(E) rfkill(E) caam_jr(E) crypto_engine(E) rng_core(E)
> > joydev(E) evdev(E) dpaa2_caam(E) caamhash_desc(E) caamalg_desc(E)
> > authenc(E) libdes(E) dpaa2_console(E) ofpart(E) caam(E) sg(E) error(E)
> > lm90(E) at24(E) spi_nor(E) mtd(E) sbsa_gwdt(E) qoriq_thermal(E)
> > layerscape_edac_mod(E) qoriq_cpufreq(E) drm(E) fuse(E) configfs(E)
> > ip_tables(E) x_tables(E) autofs4(E) ext4(E) crc32c_generic(E) crc16(E)
> > mbcache(E) jbd2(E) hid_generic(E) usbhid(E) hid(E) dm_crypt(E) dm_mod(E)
> > sd_mod(E) fsl_dpaa2_ptp(E) ptp_qoriq(E) fsl_dpaa2_eth(E)
> > xhci_plat_hcd(E) xhci_hcd(E) usbcore(E) aes_ce_blk(E) crypto_simd(E)
> > cryptd(E) aes_ce_cipher(E) ghash_ce(E) gf128mul(E) at803x(E) libaes(E)
> > fsl_mc_dpio(E) pcs_lynx(E) rtc_pcf2127(E) sha2_ce(E) phylink(E)
> > xgmac_mdio(E) regmap_spi(E) of_mdio(E) sha256_arm64(E)
> > i2c_mux_pca954x(E) fixed_phy(E) i2c_mux(E) sha1_ce(E) ptp(E) libphy(E)
> > [  714.465131]  pps_core(E) ahci_qoriq(E) libahci_platform(E) nvme(E)
> > libahci(E) nvme_core(E) t10_pi(E) libata(E) crc_t10dif(E)
> > crct10dif_generic(E) crct10dif_common(E) dwc3(E) scsi_mod(E) udc_core(E)
> > roles(E) ulpi(E) sdhci_of_esdhc(E) sdhci_pltfm(E) sdhci(E)
> > spi_nxp_fspi(E) i2c_imx(E) fixed(E)
> > [  714.465192] CPU: 13 PID: 0 Comm: swapper/13 Tainted: G        W   E
> > 5.10.0-rc7-00001-gba98d13279ca #52
> > [  714.465196] Hardware name: SolidRun LX2160A Honeycomb (DT)
> > [  714.465202] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
> > [  714.465207] pc : __arm_lpae_map+0x2d4/0x30c
> > [  714.465211] lr : __arm_lpae_map+0x114/0x30c
> > [  714.465215] sp : ffff80001006b340
> > [  714.465219] x29: ffff80001006b340 x28: 0000002086538003
> > [  714.465227] x27: 0000000000000a20 x26: 0000000000001000
> > [  714.465236] x25: 0000000000000f44 x24: 00000020adf8d000
> > [  714.465245] x23: 0000000000000001 x22: 0000fffffaeca000
> > [  714.465253] x21: 0000000000000003 x20: ffff19b60d64d200
> > [  714.465261] x19: 00000000000000ca x18: 0000000000000000
> > [  714.465270] x17: 0000000000000000 x16: ffffcccb7cf3ca20
> > [  714.465278] x15: 0000000000000000 x14: 0000000000000000
> > [  714.465286] x13: 0000000000000003 x12: 0000000000000010
> > [  714.465294] x11: 0000000000000000 x10: 0000000000000002
> > [  714.465302] x9 : ffffcccb7d5b6e78 x8 : 00000000000001ff
> > [  714.465311] x7 : ffff19b606538650 x6 : ffff19b606538000
> > [  714.465319] x5 : 0000000000000009 x4 : 0000000000000f44
> > [  714.465327] x3 : 0000000000001000 x2 : 00000020adf8d000
> > [  714.465335] x1 : 0000000000000002 x0 : 0000000000000003
> > [  714.465343] Call trace:
> > [  714.465348]  __arm_lpae_map+0x2d4/0x30c
> > [  714.465353]  __arm_lpae_map+0x114/0x30c
> > [  714.465357]  __arm_lpae_map+0x114/0x30c
> > [  714.465362]  __arm_lpae_map+0x114/0x30c
> > [  714.465366]  arm_lpae_map+0xf4/0x180
> > [  714.465373]  arm_smmu_map+0x4c/0xc0
> > [  714.465379]  __iommu_map+0x100/0x2bc
> > [  714.465385]  iommu_map_atomic+0x20/0x30
> > [  714.465391]  __iommu_dma_map+0xb0/0x110
> > [  714.465397]  iommu_dma_map_page+0xb8/0x120
> > [  714.465404]  dma_map_page_attrs+0x1a8/0x210
> > [  714.465413]  __dpaa2_eth_tx+0x384/0xbd0 [fsl_dpaa2_eth]
> > [  714.465421]  dpaa2_eth_tx+0x84/0x134 [fsl_dpaa2_eth]
> > [  714.465427]  dev_hard_start_xmit+0x10c/0x2b0
> > [  714.465433]  sch_direct_xmit+0x1a0/0x550
> > [  714.465438]  __qdisc_run+0x140/0x670
> > [  714.465443]  __dev_queue_xmit+0x6c4/0xa74
> > [  714.465449]  dev_queue_xmit+0x20/0x2c
> > [  714.465463]  br_dev_queue_push_xmit+0xc4/0x1a0 [bridge]
> > [  714.465476]  br_forward_finish+0xdc/0xf0 [bridge]
> > [  714.465489]  __br_forward+0x160/0x1c0 [bridge]
> > [  714.465502]  br_forward+0x13c/0x160 [bridge]
> > [  714.465514]  br_dev_xmit+0x228/0x3b0 [bridge]
> > [  714.465520]  dev_hard_start_xmit+0x10c/0x2b0
> > [  714.465526]  __dev_queue_xmit+0x8f0/0xa74
> > [  714.465531]  dev_queue_xmit+0x20/0x2c
> > [  714.465538]  arp_xmit+0xc0/0xd0
> > [  714.465544]  arp_send_dst+0x78/0xa0
> > [  714.465550]  arp_solicit+0xf4/0x260
> > [  714.465554]  neigh_probe+0x64/0xb0
> > [  714.465560]  neigh_timer_handler+0x2f4/0x400
> > [  714.465566]  call_timer_fn+0x3c/0x184
> > [  714.465572]  __run_timers.part.0+0x2bc/0x370
> > [  714.465578]  run_timer_softirq+0x48/0x80
> > [  714.465583]  __do_softirq+0x120/0x36c
> > [  714.465589]  irq_exit+0xac/0x100
> > [  714.465596]  __handle_domain_irq+0x8c/0xf0
> > [  714.465600]  gic_handle_irq+0xcc/0x14c
> > [  714.465605]  el1_irq+0xc4/0x180
> > [  714.465610]  arch_cpu_idle+0x18/0x30
> > [  714.465617]  default_idle_call+0x4c/0x180
> > [  714.465623]  do_idle+0x238/0x2b0
> > [  714.465629]  cpu_startup_entry+0x30/0xa0
> > [  714.465636]  secondary_start_kernel+0x134/0x180
> > [  714.465640] ---[ end trace a84a7f61b559005f ]---
> >
> >
> > Given it is the iommu code that is provoking the warning I should
> > probably mention that the board I have requires
> > arm-smmu.disable_bypass=0 on the kernel command line in order to boot.
> > Also if it matters I am running the latest firmware from Solidrun
> > which is based on LSDK-20.04.
> >
>
> Hmmm, from what I remember I think I tested this with the smmu bypassed
> so that is why I didn't catch it.
>
> > Is there any reason for this code not to be working for LX2160A?
>
> I wouldn't expect this to be LX2160A specific but rather a bug in the
> implementation.. sorry.
>
> Let me reproduce it and see if I can get to the bottom of it and I will
> get back with some more info.
>
> Ioana

Ioana,

I reported this issue to Calvin last week.  I can verify that reverting that
change also fixes the issue for me.

-Jon

>
> >
> > Daniel.
> >
> >
> > PS A few months have gone by so I decided not to trim the patch out
> >    of this reply so you don't have to go digging!
> >
> >
> >
> > >  .../freescale/dpaa2/dpaa2-eth-debugfs.c       |   7 +-
> > >  .../net/ethernet/freescale/dpaa2/dpaa2-eth.c  | 177 +++++++++++++++---
> > >  .../net/ethernet/freescale/dpaa2/dpaa2-eth.h  |   9 +-
> > >  .../ethernet/freescale/dpaa2/dpaa2-ethtool.c  |   1 -
> > >  4 files changed, 160 insertions(+), 34 deletions(-)
> > >
> > > diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c
> > > index 2880ca02d7e7..5cb357c74dec 100644
> > > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c
> > > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c
> > > @@ -19,14 +19,14 @@ static int dpaa2_dbg_cpu_show(struct seq_file *file, void *offset)
> > >     int i;
> > >
> > >     seq_printf(file, "Per-CPU stats for %s\n", priv->net_dev->name);
> > > -   seq_printf(file, "%s%16s%16s%16s%16s%16s%16s%16s%16s%16s\n",
> > > +   seq_printf(file, "%s%16s%16s%16s%16s%16s%16s%16s%16s\n",
> > >                "CPU", "Rx", "Rx Err", "Rx SG", "Tx", "Tx Err", "Tx conf",
> > > -              "Tx SG", "Tx realloc", "Enq busy");
> > > +              "Tx SG", "Enq busy");
> > >
> > >     for_each_online_cpu(i) {
> > >             stats = per_cpu_ptr(priv->percpu_stats, i);
> > >             extras = per_cpu_ptr(priv->percpu_extras, i);
> > > -           seq_printf(file, "%3d%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu\n",
> > > +           seq_printf(file, "%3d%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu\n",
> > >                        i,
> > >                        stats->rx_packets,
> > >                        stats->rx_errors,
> > > @@ -35,7 +35,6 @@ static int dpaa2_dbg_cpu_show(struct seq_file *file, void *offset)
> > >                        stats->tx_errors,
> > >                        extras->tx_conf_frames,
> > >                        extras->tx_sg_frames,
> > > -                      extras->tx_reallocs,
> > >                        extras->tx_portal_busy);
> > >     }
> > >
> > > diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > > index 712bbfdbe7d7..4a264b75c035 100644
> > > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > > @@ -685,6 +685,86 @@ static int build_sg_fd(struct dpaa2_eth_priv *priv,
> > >     return err;
> > >  }
> > >
> > > +/* Create a SG frame descriptor based on a linear skb.
> > > + *
> > > + * This function is used on the Tx path when the skb headroom is not large
> > > + * enough for the HW requirements, thus instead of realloc-ing the skb we
> > > + * create a SG frame descriptor with only one entry.
> > > + */
> > > +static int build_sg_fd_single_buf(struct dpaa2_eth_priv *priv,
> > > +                             struct sk_buff *skb,
> > > +                             struct dpaa2_fd *fd)
> > > +{
> > > +   struct device *dev = priv->net_dev->dev.parent;
> > > +   struct dpaa2_eth_sgt_cache *sgt_cache;
> > > +   struct dpaa2_sg_entry *sgt;
> > > +   struct dpaa2_eth_swa *swa;
> > > +   dma_addr_t addr, sgt_addr;
> > > +   void *sgt_buf = NULL;
> > > +   int sgt_buf_size;
> > > +   int err;
> > > +
> > > +   /* Prepare the HW SGT structure */
> > > +   sgt_cache = this_cpu_ptr(priv->sgt_cache);
> > > +   sgt_buf_size = priv->tx_data_offset + sizeof(struct dpaa2_sg_entry);
> > > +
> > > +   if (sgt_cache->count == 0)
> > > +           sgt_buf = kzalloc(sgt_buf_size + DPAA2_ETH_TX_BUF_ALIGN,
> > > +                             GFP_ATOMIC);
> > > +   else
> > > +           sgt_buf = sgt_cache->buf[--sgt_cache->count];
> > > +   if (unlikely(!sgt_buf))
> > > +           return -ENOMEM;
> > > +
> > > +   sgt_buf = PTR_ALIGN(sgt_buf, DPAA2_ETH_TX_BUF_ALIGN);
> > > +   sgt = (struct dpaa2_sg_entry *)(sgt_buf + priv->tx_data_offset);
> > > +
> > > +   addr = dma_map_single(dev, skb->data, skb->len, DMA_BIDIRECTIONAL);
> > > +   if (unlikely(dma_mapping_error(dev, addr))) {
> > > +           err = -ENOMEM;
> > > +           goto data_map_failed;
> > > +   }
> > > +
> > > +   /* Fill in the HW SGT structure */
> > > +   dpaa2_sg_set_addr(sgt, addr);
> > > +   dpaa2_sg_set_len(sgt, skb->len);
> > > +   dpaa2_sg_set_final(sgt, true);
> > > +
> > > +   /* Store the skb backpointer in the SGT buffer */
> > > +   swa = (struct dpaa2_eth_swa *)sgt_buf;
> > > +   swa->type = DPAA2_ETH_SWA_SINGLE;
> > > +   swa->single.skb = skb;
> > > +   swa->sg.sgt_size = sgt_buf_size;
> > > +
> > > +   /* Separately map the SGT buffer */
> > > +   sgt_addr = dma_map_single(dev, sgt_buf, sgt_buf_size, DMA_BIDIRECTIONAL);
> > > +   if (unlikely(dma_mapping_error(dev, sgt_addr))) {
> > > +           err = -ENOMEM;
> > > +           goto sgt_map_failed;
> > > +   }
> > > +
> > > +   dpaa2_fd_set_offset(fd, priv->tx_data_offset);
> > > +   dpaa2_fd_set_format(fd, dpaa2_fd_sg);
> > > +   dpaa2_fd_set_addr(fd, sgt_addr);
> > > +   dpaa2_fd_set_len(fd, skb->len);
> > > +   dpaa2_fd_set_ctrl(fd, FD_CTRL_PTA);
> > > +
> > > +   if (priv->tx_tstamp && skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)
> > > +           enable_tx_tstamp(fd, sgt_buf);
> > > +
> > > +   return 0;
> > > +
> > > +sgt_map_failed:
> > > +   dma_unmap_single(dev, addr, skb->len, DMA_BIDIRECTIONAL);
> > > +data_map_failed:
> > > +   if (sgt_cache->count >= DPAA2_ETH_SGT_CACHE_SIZE)
> > > +           kfree(sgt_buf);
> > > +   else
> > > +           sgt_cache->buf[sgt_cache->count++] = sgt_buf;
> > > +
> > > +   return err;
> > > +}
> > > +
> > >  /* Create a frame descriptor based on a linear skb */
> > >  static int build_single_fd(struct dpaa2_eth_priv *priv,
> > >                        struct sk_buff *skb,
> > > @@ -743,13 +823,16 @@ static void free_tx_fd(const struct dpaa2_eth_priv *priv,
> > >                    const struct dpaa2_fd *fd, bool in_napi)
> > >  {
> > >     struct device *dev = priv->net_dev->dev.parent;
> > > -   dma_addr_t fd_addr;
> > > +   dma_addr_t fd_addr, sg_addr;
> > >     struct sk_buff *skb = NULL;
> > >     unsigned char *buffer_start;
> > >     struct dpaa2_eth_swa *swa;
> > >     u8 fd_format = dpaa2_fd_get_format(fd);
> > >     u32 fd_len = dpaa2_fd_get_len(fd);
> > >
> > > +   struct dpaa2_eth_sgt_cache *sgt_cache;
> > > +   struct dpaa2_sg_entry *sgt;
> > > +
> > >     fd_addr = dpaa2_fd_get_addr(fd);
> > >     buffer_start = dpaa2_iova_to_virt(priv->iommu_domain, fd_addr);
> > >     swa = (struct dpaa2_eth_swa *)buffer_start;
> > > @@ -769,16 +852,29 @@ static void free_tx_fd(const struct dpaa2_eth_priv *priv,
> > >                                      DMA_BIDIRECTIONAL);
> > >             }
> > >     } else if (fd_format == dpaa2_fd_sg) {
> > > -           skb = swa->sg.skb;
> > > +           if (swa->type == DPAA2_ETH_SWA_SG) {
> > > +                   skb = swa->sg.skb;
> > > +
> > > +                   /* Unmap the scatterlist */
> > > +                   dma_unmap_sg(dev, swa->sg.scl, swa->sg.num_sg,
> > > +                                DMA_BIDIRECTIONAL);
> > > +                   kfree(swa->sg.scl);
> > >
> > > -           /* Unmap the scatterlist */
> > > -           dma_unmap_sg(dev, swa->sg.scl, swa->sg.num_sg,
> > > -                        DMA_BIDIRECTIONAL);
> > > -           kfree(swa->sg.scl);
> > > +                   /* Unmap the SGT buffer */
> > > +                   dma_unmap_single(dev, fd_addr, swa->sg.sgt_size,
> > > +                                    DMA_BIDIRECTIONAL);
> > > +           } else {
> > > +                   skb = swa->single.skb;
> > >
> > > -           /* Unmap the SGT buffer */
> > > -           dma_unmap_single(dev, fd_addr, swa->sg.sgt_size,
> > > -                            DMA_BIDIRECTIONAL);
> > > +                   /* Unmap the SGT Buffer */
> > > +                   dma_unmap_single(dev, fd_addr, swa->single.sgt_size,
> > > +                                    DMA_BIDIRECTIONAL);
> > > +
> > > +                   sgt = (struct dpaa2_sg_entry *)(buffer_start +
> > > +                                                   priv->tx_data_offset);
> > > +                   sg_addr = dpaa2_sg_get_addr(sgt);
> > > +                   dma_unmap_single(dev, sg_addr, skb->len, DMA_BIDIRECTIONAL);
> > > +           }
> > >     } else {
> > >             netdev_dbg(priv->net_dev, "Invalid FD format\n");
> > >             return;
> > > @@ -808,8 +904,17 @@ static void free_tx_fd(const struct dpaa2_eth_priv *priv,
> > >     }
> > >
> > >     /* Free SGT buffer allocated on tx */
> > > -   if (fd_format != dpaa2_fd_single)
> > > -           skb_free_frag(buffer_start);
> > > +   if (fd_format != dpaa2_fd_single) {
> > > +           sgt_cache = this_cpu_ptr(priv->sgt_cache);
> > > +           if (swa->type == DPAA2_ETH_SWA_SG) {
> > > +                   skb_free_frag(buffer_start);
> > > +           } else {
> > > +                   if (sgt_cache->count >= DPAA2_ETH_SGT_CACHE_SIZE)
> > > +                           kfree(buffer_start);
> > > +                   else
> > > +                           sgt_cache->buf[sgt_cache->count++] = buffer_start;
> > > +           }
> > > +   }
> > >
> > >     /* Move on with skb release */
> > >     napi_consume_skb(skb, in_napi);
> > > @@ -833,22 +938,6 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
> > >     percpu_extras = this_cpu_ptr(priv->percpu_extras);
> > >
> > >     needed_headroom = dpaa2_eth_needed_headroom(priv, skb);
> > > -   if (skb_headroom(skb) < needed_headroom) {
> > > -           struct sk_buff *ns;
> > > -
> > > -           ns = skb_realloc_headroom(skb, needed_headroom);
> > > -           if (unlikely(!ns)) {
> > > -                   percpu_stats->tx_dropped++;
> > > -                   goto err_alloc_headroom;
> > > -           }
> > > -           percpu_extras->tx_reallocs++;
> > > -
> > > -           if (skb->sk)
> > > -                   skb_set_owner_w(ns, skb->sk);
> > > -
> > > -           dev_kfree_skb(skb);
> > > -           skb = ns;
> > > -   }
> > >
> > >     /* We'll be holding a back-reference to the skb until Tx Confirmation;
> > >      * we don't want that overwritten by a concurrent Tx with a cloned skb.
> > > @@ -867,6 +956,10 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
> > >             err = build_sg_fd(priv, skb, &fd);
> > >             percpu_extras->tx_sg_frames++;
> > >             percpu_extras->tx_sg_bytes += skb->len;
> > > +   } else if (skb_headroom(skb) < needed_headroom) {
> > > +           err = build_sg_fd_single_buf(priv, skb, &fd);
> > > +           percpu_extras->tx_sg_frames++;
> > > +           percpu_extras->tx_sg_bytes += skb->len;
> > >     } else {
> > >             err = build_single_fd(priv, skb, &fd);
> > >     }
> > > @@ -924,7 +1017,6 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
> > >     return NETDEV_TX_OK;
> > >
> > >  err_build_fd:
> > > -err_alloc_headroom:
> > >     dev_kfree_skb(skb);
> > >
> > >     return NETDEV_TX_OK;
> > > @@ -1161,6 +1253,22 @@ static int refill_pool(struct dpaa2_eth_priv *priv,
> > >     return 0;
> > >  }
> > >
> > > +static void dpaa2_eth_sgt_cache_drain(struct dpaa2_eth_priv *priv)
> > > +{
> > > +   struct dpaa2_eth_sgt_cache *sgt_cache;
> > > +   u16 count;
> > > +   int k, i;
> > > +
> > > +   for_each_online_cpu(k) {
> > > +           sgt_cache = per_cpu_ptr(priv->sgt_cache, k);
> > > +           count = sgt_cache->count;
> > > +
> > > +           for (i = 0; i < count; i++)
> > > +                   kfree(sgt_cache->buf[i]);
> > > +           sgt_cache->count = 0;
> > > +   }
> > > +}
> > > +
> > >  static int pull_channel(struct dpaa2_eth_channel *ch)
> > >  {
> > >     int err;
> > > @@ -1562,6 +1670,9 @@ static int dpaa2_eth_stop(struct net_device *net_dev)
> > >     /* Empty the buffer pool */
> > >     drain_pool(priv);
> > >
> > > +   /* Empty the Scatter-Gather Buffer cache */
> > > +   dpaa2_eth_sgt_cache_drain(priv);
> > > +
> > >     return 0;
> > >  }
> > >
> > > @@ -3846,6 +3957,13 @@ static int dpaa2_eth_probe(struct fsl_mc_device *dpni_dev)
> > >             goto err_alloc_percpu_extras;
> > >     }
> > >
> > > +   priv->sgt_cache = alloc_percpu(*priv->sgt_cache);
> > > +   if (!priv->sgt_cache) {
> > > +           dev_err(dev, "alloc_percpu(sgt_cache) failed\n");
> > > +           err = -ENOMEM;
> > > +           goto err_alloc_sgt_cache;
> > > +   }
> > > +
> > >     err = netdev_init(net_dev);
> > >     if (err)
> > >             goto err_netdev_init;
> > > @@ -3914,6 +4032,8 @@ static int dpaa2_eth_probe(struct fsl_mc_device *dpni_dev)
> > >  err_alloc_rings:
> > >  err_csum:
> > >  err_netdev_init:
> > > +   free_percpu(priv->sgt_cache);
> > > +err_alloc_sgt_cache:
> > >     free_percpu(priv->percpu_extras);
> > >  err_alloc_percpu_extras:
> > >     free_percpu(priv->percpu_stats);
> > > @@ -3959,6 +4079,7 @@ static int dpaa2_eth_remove(struct fsl_mc_device *ls_dev)
> > >             fsl_mc_free_irqs(ls_dev);
> > >
> > >     free_rings(priv);
> > > +   free_percpu(priv->sgt_cache);
> > >     free_percpu(priv->percpu_stats);
> > >     free_percpu(priv->percpu_extras);
> > >
> > > diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
> > > index 2d7ada0f0dbd..9e4ceb92f240 100644
> > > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
> > > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
> > > @@ -125,6 +125,7 @@ struct dpaa2_eth_swa {
> > >     union {
> > >             struct {
> > >                     struct sk_buff *skb;
> > > +                   int sgt_size;
> > >             } single;
> > >             struct {
> > >                     struct sk_buff *skb;
> > > @@ -282,7 +283,6 @@ struct dpaa2_eth_drv_stats {
> > >     __u64   tx_conf_bytes;
> > >     __u64   tx_sg_frames;
> > >     __u64   tx_sg_bytes;
> > > -   __u64   tx_reallocs;
> > >     __u64   rx_sg_frames;
> > >     __u64   rx_sg_bytes;
> > >     /* Enqueues retried due to portal busy */
> > > @@ -395,6 +395,12 @@ struct dpaa2_eth_cls_rule {
> > >     u8 in_use;
> > >  };
> > >
> > > +#define DPAA2_ETH_SGT_CACHE_SIZE   256
> > > +struct dpaa2_eth_sgt_cache {
> > > +   void *buf[DPAA2_ETH_SGT_CACHE_SIZE];
> > > +   u16 count;
> > > +};
> > > +
> > >  /* Driver private data */
> > >  struct dpaa2_eth_priv {
> > >     struct net_device *net_dev;
> > > @@ -409,6 +415,7 @@ struct dpaa2_eth_priv {
> > >
> > >     u8 num_channels;
> > >     struct dpaa2_eth_channel *channel[DPAA2_ETH_MAX_DPCONS];
> > > +   struct dpaa2_eth_sgt_cache __percpu *sgt_cache;
> > >
> > >     struct dpni_attr dpni_attrs;
> > >     u16 dpni_ver_major;
> > > diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
> > > index e88269fe3de7..c4cbbcaa9a3f 100644
> > > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
> > > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
> > > @@ -43,7 +43,6 @@ static char dpaa2_ethtool_extras[][ETH_GSTRING_LEN] = {
> > >     "[drv] tx conf bytes",
> > >     "[drv] tx sg frames",
> > >     "[drv] tx sg bytes",
> > > -   "[drv] tx realloc frames",
> > >     "[drv] rx sg frames",
> > >     "[drv] rx sg bytes",
> > >     "[drv] enqueue portal busy",
> > > --
> > > 2.25.1

Re: [PATCH RESEND net-next 1/2] dpaa2-eth: send a scatter-gather FD instead of realloc-ing

[Ioana Ciornei]

On Thu, Dec 10, 2020 at 08:06:36PM +0200, Ioana Ciornei wrote:
> [Added also the netdev mailing list, I haven't heard of linux-netdev
> before but kept it]
> 
> On Thu, Dec 10, 2020 at 05:31:56PM +0000, Daniel Thompson wrote:
> > Hi Ioana
> 
> Hi Daniel,
> 
> > 
> > On Mon, Jun 29, 2020 at 06:47:11PM +0000, Ioana Ciornei wrote:
> > > Instead of realloc-ing the skb on the Tx path when the provided headroom
> > > is smaller than the HW requirements, create a Scatter/Gather frame
> > > descriptor with only one entry.
> > > 
> > > Remove the '[drv] tx realloc frames' counter exposed previously through
> > > ethtool since it is no longer used.
> > > 
> > > Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> > > ---
> > 
> > I've been chasing down a networking regression on my LX2160A board
> > (Honeycomb LX2K based on CEx7 LX2160A COM) that first appeared in v5.9.
> > 
> > It makes the board unreliable opening outbound connections meaning
> > things like `apt update` or `git fetch` often can't open the connection.
> > It does not happen all the time but is sufficient to make the boards
> > built-in networking useless for workstation use.
> > 
> > The problem is strongly linked to warnings in the logs so I used the
> > warnings to bisect down to locate the cause of the regression and it
> > pinpointed this patch. I have confirmed that in both v5.9 and v5.10-rc7
> > that reverting this patch (and fixing up the merge issues) fixes the
> > regression and the warnings stop appearing.
> > 
> > A typical example of the warning is below (io-pgtable-arm.c:281 is an
> > error path that I guess would cause dma_map_page_attrs() to return
> > an error):
> > 
> > [  714.464927] WARNING: CPU: 13 PID: 0 at
> > drivers/iommu/io-pgtable-arm.c:281 __arm_lpae_map+0x2d4/0x30c
> > [  714.464930] Modules linked in: snd_seq_dummy(E) snd_hrtimer(E)
> > snd_seq(E) snd_seq_device(E) snd_timer(E) snd(E) soundcore(E) bridge(E)
> > stp(E) llc(E) rfkill(E) caam_jr(E) crypto_engine(E) rng_core(E)
> > joydev(E) evdev(E) dpaa2_caam(E) caamhash_desc(E) caamalg_desc(E)
> > authenc(E) libdes(E) dpaa2_console(E) ofpart(E) caam(E) sg(E) error(E)
> > lm90(E) at24(E) spi_nor(E) mtd(E) sbsa_gwdt(E) qoriq_thermal(E)
> > layerscape_edac_mod(E) qoriq_cpufreq(E) drm(E) fuse(E) configfs(E)
> > ip_tables(E) x_tables(E) autofs4(E) ext4(E) crc32c_generic(E) crc16(E)
> > mbcache(E) jbd2(E) hid_generic(E) usbhid(E) hid(E) dm_crypt(E) dm_mod(E)
> > sd_mod(E) fsl_dpaa2_ptp(E) ptp_qoriq(E) fsl_dpaa2_eth(E)
> > xhci_plat_hcd(E) xhci_hcd(E) usbcore(E) aes_ce_blk(E) crypto_simd(E)
> > cryptd(E) aes_ce_cipher(E) ghash_ce(E) gf128mul(E) at803x(E) libaes(E)
> > fsl_mc_dpio(E) pcs_lynx(E) rtc_pcf2127(E) sha2_ce(E) phylink(E)
> > xgmac_mdio(E) regmap_spi(E) of_mdio(E) sha256_arm64(E)
> > i2c_mux_pca954x(E) fixed_phy(E) i2c_mux(E) sha1_ce(E) ptp(E) libphy(E)
> > [  714.465131]  pps_core(E) ahci_qoriq(E) libahci_platform(E) nvme(E)
> > libahci(E) nvme_core(E) t10_pi(E) libata(E) crc_t10dif(E)
> > crct10dif_generic(E) crct10dif_common(E) dwc3(E) scsi_mod(E) udc_core(E)
> > roles(E) ulpi(E) sdhci_of_esdhc(E) sdhci_pltfm(E) sdhci(E)
> > spi_nxp_fspi(E) i2c_imx(E) fixed(E)
> > [  714.465192] CPU: 13 PID: 0 Comm: swapper/13 Tainted: G        W   E
> > 5.10.0-rc7-00001-gba98d13279ca #52
> > [  714.465196] Hardware name: SolidRun LX2160A Honeycomb (DT)
> > [  714.465202] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
> > [  714.465207] pc : __arm_lpae_map+0x2d4/0x30c
> > [  714.465211] lr : __arm_lpae_map+0x114/0x30c
> > [  714.465215] sp : ffff80001006b340
> > [  714.465219] x29: ffff80001006b340 x28: 0000002086538003 
> > [  714.465227] x27: 0000000000000a20 x26: 0000000000001000 
> > [  714.465236] x25: 0000000000000f44 x24: 00000020adf8d000 
> > [  714.465245] x23: 0000000000000001 x22: 0000fffffaeca000 
> > [  714.465253] x21: 0000000000000003 x20: ffff19b60d64d200 
> > [  714.465261] x19: 00000000000000ca x18: 0000000000000000 
> > [  714.465270] x17: 0000000000000000 x16: ffffcccb7cf3ca20 
> > [  714.465278] x15: 0000000000000000 x14: 0000000000000000 
> > [  714.465286] x13: 0000000000000003 x12: 0000000000000010 
> > [  714.465294] x11: 0000000000000000 x10: 0000000000000002 
> > [  714.465302] x9 : ffffcccb7d5b6e78 x8 : 00000000000001ff 
> > [  714.465311] x7 : ffff19b606538650 x6 : ffff19b606538000 
> > [  714.465319] x5 : 0000000000000009 x4 : 0000000000000f44 
> > [  714.465327] x3 : 0000000000001000 x2 : 00000020adf8d000 
> > [  714.465335] x1 : 0000000000000002 x0 : 0000000000000003 
> > [  714.465343] Call trace:
> > [  714.465348]  __arm_lpae_map+0x2d4/0x30c
> > [  714.465353]  __arm_lpae_map+0x114/0x30c
> > [  714.465357]  __arm_lpae_map+0x114/0x30c
> > [  714.465362]  __arm_lpae_map+0x114/0x30c
> > [  714.465366]  arm_lpae_map+0xf4/0x180
> > [  714.465373]  arm_smmu_map+0x4c/0xc0
> > [  714.465379]  __iommu_map+0x100/0x2bc
> > [  714.465385]  iommu_map_atomic+0x20/0x30
> > [  714.465391]  __iommu_dma_map+0xb0/0x110
> > [  714.465397]  iommu_dma_map_page+0xb8/0x120
> > [  714.465404]  dma_map_page_attrs+0x1a8/0x210
> > [  714.465413]  __dpaa2_eth_tx+0x384/0xbd0 [fsl_dpaa2_eth]
> > [  714.465421]  dpaa2_eth_tx+0x84/0x134 [fsl_dpaa2_eth]
> > [  714.465427]  dev_hard_start_xmit+0x10c/0x2b0
> > [  714.465433]  sch_direct_xmit+0x1a0/0x550
> > [  714.465438]  __qdisc_run+0x140/0x670
> > [  714.465443]  __dev_queue_xmit+0x6c4/0xa74
> > [  714.465449]  dev_queue_xmit+0x20/0x2c
> > [  714.465463]  br_dev_queue_push_xmit+0xc4/0x1a0 [bridge]
> > [  714.465476]  br_forward_finish+0xdc/0xf0 [bridge]
> > [  714.465489]  __br_forward+0x160/0x1c0 [bridge]
> > [  714.465502]  br_forward+0x13c/0x160 [bridge]
> > [  714.465514]  br_dev_xmit+0x228/0x3b0 [bridge]
> > [  714.465520]  dev_hard_start_xmit+0x10c/0x2b0
> > [  714.465526]  __dev_queue_xmit+0x8f0/0xa74
> > [  714.465531]  dev_queue_xmit+0x20/0x2c
> > [  714.465538]  arp_xmit+0xc0/0xd0
> > [  714.465544]  arp_send_dst+0x78/0xa0
> > [  714.465550]  arp_solicit+0xf4/0x260
> > [  714.465554]  neigh_probe+0x64/0xb0
> > [  714.465560]  neigh_timer_handler+0x2f4/0x400
> > [  714.465566]  call_timer_fn+0x3c/0x184
> > [  714.465572]  __run_timers.part.0+0x2bc/0x370
> > [  714.465578]  run_timer_softirq+0x48/0x80
> > [  714.465583]  __do_softirq+0x120/0x36c
> > [  714.465589]  irq_exit+0xac/0x100
> > [  714.465596]  __handle_domain_irq+0x8c/0xf0
> > [  714.465600]  gic_handle_irq+0xcc/0x14c
> > [  714.465605]  el1_irq+0xc4/0x180
> > [  714.465610]  arch_cpu_idle+0x18/0x30
> > [  714.465617]  default_idle_call+0x4c/0x180
> > [  714.465623]  do_idle+0x238/0x2b0
> > [  714.465629]  cpu_startup_entry+0x30/0xa0
> > [  714.465636]  secondary_start_kernel+0x134/0x180
> > [  714.465640] ---[ end trace a84a7f61b559005f ]---
> > 
> > 
> > Given it is the iommu code that is provoking the warning I should
> > probably mention that the board I have requires
> > arm-smmu.disable_bypass=0 on the kernel command line in order to boot.
> > Also if it matters I am running the latest firmware from Solidrun
> > which is based on LSDK-20.04.
> > 
> 
> Hmmm, from what I remember I think I tested this with the smmu bypassed
> so that is why I didn't catch it.
> 
> > Is there any reason for this code not to be working for LX2160A?
> 
> I wouldn't expect this to be LX2160A specific but rather a bug in the
> implementation.. sorry.
> 
> Let me reproduce it and see if I can get to the bottom of it and I will
> get back with some more info.
> 

Hi Daniel,

It seems that the dma-unmapping on the SGT buffer was incorrectly done
with a zero size since on the Tx path I initialized the improper field.

Could you test the following diff and let me know if you can generate
the WARNINGs anymore?

--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
@@ -878,7 +878,7 @@ static int dpaa2_eth_build_sg_fd_single_buf(struct dpaa2_eth_priv *priv,
        swa = (struct dpaa2_eth_swa *)sgt_buf;
        swa->type = DPAA2_ETH_SWA_SINGLE;
        swa->single.skb = skb;
-       swa->sg.sgt_size = sgt_buf_size;
+       swa->single.sgt_size = sgt_buf_size;
 
        /* Separately map the SGT buffer */
        sgt_addr = dma_map_single(dev, sgt_buf, sgt_buf_size, DMA_BIDIRECTIONAL);


Ioana

Re: [PATCH RESEND net-next 1/2] dpaa2-eth: send a scatter-gather FD instead of realloc-ing

[Daniel Thompson]

On Fri, Dec 11, 2020 at 02:01:28PM +0000, Ioana Ciornei wrote:
> On Thu, Dec 10, 2020 at 08:06:36PM +0200, Ioana Ciornei wrote:
> > [Added also the netdev mailing list, I haven't heard of linux-netdev
> > before but kept it]
> > 
> > On Thu, Dec 10, 2020 at 05:31:56PM +0000, Daniel Thompson wrote:
> > > Hi Ioana
> > 
> > Hi Daniel,
> > 
> > > 
> > > On Mon, Jun 29, 2020 at 06:47:11PM +0000, Ioana Ciornei wrote:
> > > > Instead of realloc-ing the skb on the Tx path when the provided headroom
> > > > is smaller than the HW requirements, create a Scatter/Gather frame
> > > > descriptor with only one entry.
> > > > 
> > > > Remove the '[drv] tx realloc frames' counter exposed previously through
> > > > ethtool since it is no longer used.
> > > > 
> > > > Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> > > > ---
> > > 
> > > I've been chasing down a networking regression on my LX2160A board
> > > (Honeycomb LX2K based on CEx7 LX2160A COM) that first appeared in v5.9.
> > > 
> > > It makes the board unreliable opening outbound connections meaning
> > > things like `apt update` or `git fetch` often can't open the connection.
> > > It does not happen all the time but is sufficient to make the boards
> > > built-in networking useless for workstation use.
> > > 
> > > The problem is strongly linked to warnings in the logs so I used the
> > > warnings to bisect down to locate the cause of the regression and it
> > > pinpointed this patch. I have confirmed that in both v5.9 and v5.10-rc7
> > > that reverting this patch (and fixing up the merge issues) fixes the
> > > regression and the warnings stop appearing.
> > > 
> > > A typical example of the warning is below (io-pgtable-arm.c:281 is an
> > > error path that I guess would cause dma_map_page_attrs() to return
> > > an error):
> > > 
> > > [  714.464927] WARNING: CPU: 13 PID: 0 at
> > > drivers/iommu/io-pgtable-arm.c:281 __arm_lpae_map+0x2d4/0x30c
> > > [  714.464930] Modules linked in: snd_seq_dummy(E) snd_hrtimer(E)
> > > snd_seq(E) snd_seq_device(E) snd_timer(E) snd(E) soundcore(E) bridge(E)
> > > stp(E) llc(E) rfkill(E) caam_jr(E) crypto_engine(E) rng_core(E)
> > > joydev(E) evdev(E) dpaa2_caam(E) caamhash_desc(E) caamalg_desc(E)
> > > authenc(E) libdes(E) dpaa2_console(E) ofpart(E) caam(E) sg(E) error(E)
> > > lm90(E) at24(E) spi_nor(E) mtd(E) sbsa_gwdt(E) qoriq_thermal(E)
> > > layerscape_edac_mod(E) qoriq_cpufreq(E) drm(E) fuse(E) configfs(E)
> > > ip_tables(E) x_tables(E) autofs4(E) ext4(E) crc32c_generic(E) crc16(E)
> > > mbcache(E) jbd2(E) hid_generic(E) usbhid(E) hid(E) dm_crypt(E) dm_mod(E)
> > > sd_mod(E) fsl_dpaa2_ptp(E) ptp_qoriq(E) fsl_dpaa2_eth(E)
> > > xhci_plat_hcd(E) xhci_hcd(E) usbcore(E) aes_ce_blk(E) crypto_simd(E)
> > > cryptd(E) aes_ce_cipher(E) ghash_ce(E) gf128mul(E) at803x(E) libaes(E)
> > > fsl_mc_dpio(E) pcs_lynx(E) rtc_pcf2127(E) sha2_ce(E) phylink(E)
> > > xgmac_mdio(E) regmap_spi(E) of_mdio(E) sha256_arm64(E)
> > > i2c_mux_pca954x(E) fixed_phy(E) i2c_mux(E) sha1_ce(E) ptp(E) libphy(E)
> > > [  714.465131]  pps_core(E) ahci_qoriq(E) libahci_platform(E) nvme(E)
> > > libahci(E) nvme_core(E) t10_pi(E) libata(E) crc_t10dif(E)
> > > crct10dif_generic(E) crct10dif_common(E) dwc3(E) scsi_mod(E) udc_core(E)
> > > roles(E) ulpi(E) sdhci_of_esdhc(E) sdhci_pltfm(E) sdhci(E)
> > > spi_nxp_fspi(E) i2c_imx(E) fixed(E)
> > > [  714.465192] CPU: 13 PID: 0 Comm: swapper/13 Tainted: G        W   E
> > > 5.10.0-rc7-00001-gba98d13279ca #52
> > > [  714.465196] Hardware name: SolidRun LX2160A Honeycomb (DT)
> > > [  714.465202] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
> > > [  714.465207] pc : __arm_lpae_map+0x2d4/0x30c
> > > [  714.465211] lr : __arm_lpae_map+0x114/0x30c
> > > [  714.465215] sp : ffff80001006b340
> > > [  714.465219] x29: ffff80001006b340 x28: 0000002086538003 
> > > [  714.465227] x27: 0000000000000a20 x26: 0000000000001000 
> > > [  714.465236] x25: 0000000000000f44 x24: 00000020adf8d000 
> > > [  714.465245] x23: 0000000000000001 x22: 0000fffffaeca000 
> > > [  714.465253] x21: 0000000000000003 x20: ffff19b60d64d200 
> > > [  714.465261] x19: 00000000000000ca x18: 0000000000000000 
> > > [  714.465270] x17: 0000000000000000 x16: ffffcccb7cf3ca20 
> > > [  714.465278] x15: 0000000000000000 x14: 0000000000000000 
> > > [  714.465286] x13: 0000000000000003 x12: 0000000000000010 
> > > [  714.465294] x11: 0000000000000000 x10: 0000000000000002 
> > > [  714.465302] x9 : ffffcccb7d5b6e78 x8 : 00000000000001ff 
> > > [  714.465311] x7 : ffff19b606538650 x6 : ffff19b606538000 
> > > [  714.465319] x5 : 0000000000000009 x4 : 0000000000000f44 
> > > [  714.465327] x3 : 0000000000001000 x2 : 00000020adf8d000 
> > > [  714.465335] x1 : 0000000000000002 x0 : 0000000000000003 
> > > [  714.465343] Call trace:
> > > [  714.465348]  __arm_lpae_map+0x2d4/0x30c
> > > [  714.465353]  __arm_lpae_map+0x114/0x30c
> > > [  714.465357]  __arm_lpae_map+0x114/0x30c
> > > [  714.465362]  __arm_lpae_map+0x114/0x30c
> > > [  714.465366]  arm_lpae_map+0xf4/0x180
> > > [  714.465373]  arm_smmu_map+0x4c/0xc0
> > > [  714.465379]  __iommu_map+0x100/0x2bc
> > > [  714.465385]  iommu_map_atomic+0x20/0x30
> > > [  714.465391]  __iommu_dma_map+0xb0/0x110
> > > [  714.465397]  iommu_dma_map_page+0xb8/0x120
> > > [  714.465404]  dma_map_page_attrs+0x1a8/0x210
> > > [  714.465413]  __dpaa2_eth_tx+0x384/0xbd0 [fsl_dpaa2_eth]
> > > [  714.465421]  dpaa2_eth_tx+0x84/0x134 [fsl_dpaa2_eth]
> > > [  714.465427]  dev_hard_start_xmit+0x10c/0x2b0
> > > [  714.465433]  sch_direct_xmit+0x1a0/0x550
> > > [  714.465438]  __qdisc_run+0x140/0x670
> > > [  714.465443]  __dev_queue_xmit+0x6c4/0xa74
> > > [  714.465449]  dev_queue_xmit+0x20/0x2c
> > > [  714.465463]  br_dev_queue_push_xmit+0xc4/0x1a0 [bridge]
> > > [  714.465476]  br_forward_finish+0xdc/0xf0 [bridge]
> > > [  714.465489]  __br_forward+0x160/0x1c0 [bridge]
> > > [  714.465502]  br_forward+0x13c/0x160 [bridge]
> > > [  714.465514]  br_dev_xmit+0x228/0x3b0 [bridge]
> > > [  714.465520]  dev_hard_start_xmit+0x10c/0x2b0
> > > [  714.465526]  __dev_queue_xmit+0x8f0/0xa74
> > > [  714.465531]  dev_queue_xmit+0x20/0x2c
> > > [  714.465538]  arp_xmit+0xc0/0xd0
> > > [  714.465544]  arp_send_dst+0x78/0xa0
> > > [  714.465550]  arp_solicit+0xf4/0x260
> > > [  714.465554]  neigh_probe+0x64/0xb0
> > > [  714.465560]  neigh_timer_handler+0x2f4/0x400
> > > [  714.465566]  call_timer_fn+0x3c/0x184
> > > [  714.465572]  __run_timers.part.0+0x2bc/0x370
> > > [  714.465578]  run_timer_softirq+0x48/0x80
> > > [  714.465583]  __do_softirq+0x120/0x36c
> > > [  714.465589]  irq_exit+0xac/0x100
> > > [  714.465596]  __handle_domain_irq+0x8c/0xf0
> > > [  714.465600]  gic_handle_irq+0xcc/0x14c
> > > [  714.465605]  el1_irq+0xc4/0x180
> > > [  714.465610]  arch_cpu_idle+0x18/0x30
> > > [  714.465617]  default_idle_call+0x4c/0x180
> > > [  714.465623]  do_idle+0x238/0x2b0
> > > [  714.465629]  cpu_startup_entry+0x30/0xa0
> > > [  714.465636]  secondary_start_kernel+0x134/0x180
> > > [  714.465640] ---[ end trace a84a7f61b559005f ]---
> > > 
> > > 
> > > Given it is the iommu code that is provoking the warning I should
> > > probably mention that the board I have requires
> > > arm-smmu.disable_bypass=0 on the kernel command line in order to boot.
> > > Also if it matters I am running the latest firmware from Solidrun
> > > which is based on LSDK-20.04.
> > > 
> > 
> > Hmmm, from what I remember I think I tested this with the smmu bypassed
> > so that is why I didn't catch it.
> > 
> > > Is there any reason for this code not to be working for LX2160A?
> > 
> > I wouldn't expect this to be LX2160A specific but rather a bug in the
> > implementation.. sorry.
> > 
> > Let me reproduce it and see if I can get to the bottom of it and I will
> > get back with some more info.
> > 
> 
> Hi Daniel,
> 
> It seems that the dma-unmapping on the SGT buffer was incorrectly done
> with a zero size since on the Tx path I initialized the improper field.
> 
> Could you test the following diff and let me know if you can generate
> the WARNINGs anymore?

I fired this up and, with your change, I've not been able to trigger
the warning with the tests that I used the drive my bisect.

Thanks for the quick response.


Daniel.


> 
> --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> @@ -878,7 +878,7 @@ static int dpaa2_eth_build_sg_fd_single_buf(struct dpaa2_eth_priv *priv,
>         swa = (struct dpaa2_eth_swa *)sgt_buf;
>         swa->type = DPAA2_ETH_SWA_SINGLE;
>         swa->single.skb = skb;
> -       swa->sg.sgt_size = sgt_buf_size;
> +       swa->single.sgt_size = sgt_buf_size;
>  
>         /* Separately map the SGT buffer */
>         sgt_addr = dma_map_single(dev, sgt_buf, sgt_buf_size, DMA_BIDIRECTIONAL);
> 
> 
> Ioana

Re: [PATCH RESEND net-next 1/2] dpaa2-eth: send a scatter-gather FD instead of realloc-ing

[Ioana Ciornei]

On Fri, Dec 11, 2020 at 04:29:14PM +0000, Daniel Thompson wrote:
> On Fri, Dec 11, 2020 at 02:01:28PM +0000, Ioana Ciornei wrote:
> > On Thu, Dec 10, 2020 at 08:06:36PM +0200, Ioana Ciornei wrote:
> > > [Added also the netdev mailing list, I haven't heard of linux-netdev
> > > before but kept it]
> > > 
> > > On Thu, Dec 10, 2020 at 05:31:56PM +0000, Daniel Thompson wrote:
> > > > Hi Ioana
> > > 
> > > Hi Daniel,
> > > 
> > > > 
> > > > On Mon, Jun 29, 2020 at 06:47:11PM +0000, Ioana Ciornei wrote:
> > > > > Instead of realloc-ing the skb on the Tx path when the provided headroom
> > > > > is smaller than the HW requirements, create a Scatter/Gather frame
> > > > > descriptor with only one entry.
> > > > > 
> > > > > Remove the '[drv] tx realloc frames' counter exposed previously through
> > > > > ethtool since it is no longer used.
> > > > > 
> > > > > Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> > > > > ---
> > > > 
> > > > I've been chasing down a networking regression on my LX2160A board
> > > > (Honeycomb LX2K based on CEx7 LX2160A COM) that first appeared in v5.9.
> > > > 
> > > > It makes the board unreliable opening outbound connections meaning
> > > > things like `apt update` or `git fetch` often can't open the connection.
> > > > It does not happen all the time but is sufficient to make the boards
> > > > built-in networking useless for workstation use.
> > > > 
> > > > The problem is strongly linked to warnings in the logs so I used the
> > > > warnings to bisect down to locate the cause of the regression and it
> > > > pinpointed this patch. I have confirmed that in both v5.9 and v5.10-rc7
> > > > that reverting this patch (and fixing up the merge issues) fixes the
> > > > regression and the warnings stop appearing.
> > > > 
> > > > A typical example of the warning is below (io-pgtable-arm.c:281 is an
> > > > error path that I guess would cause dma_map_page_attrs() to return
> > > > an error):
> > > > 
> > > > [  714.464927] WARNING: CPU: 13 PID: 0 at
> > > > drivers/iommu/io-pgtable-arm.c:281 __arm_lpae_map+0x2d4/0x30c
> > > > [  714.464930] Modules linked in: snd_seq_dummy(E) snd_hrtimer(E)
> > > > snd_seq(E) snd_seq_device(E) snd_timer(E) snd(E) soundcore(E) bridge(E)
> > > > stp(E) llc(E) rfkill(E) caam_jr(E) crypto_engine(E) rng_core(E)
> > > > joydev(E) evdev(E) dpaa2_caam(E) caamhash_desc(E) caamalg_desc(E)
> > > > authenc(E) libdes(E) dpaa2_console(E) ofpart(E) caam(E) sg(E) error(E)
> > > > lm90(E) at24(E) spi_nor(E) mtd(E) sbsa_gwdt(E) qoriq_thermal(E)
> > > > layerscape_edac_mod(E) qoriq_cpufreq(E) drm(E) fuse(E) configfs(E)
> > > > ip_tables(E) x_tables(E) autofs4(E) ext4(E) crc32c_generic(E) crc16(E)
> > > > mbcache(E) jbd2(E) hid_generic(E) usbhid(E) hid(E) dm_crypt(E) dm_mod(E)
> > > > sd_mod(E) fsl_dpaa2_ptp(E) ptp_qoriq(E) fsl_dpaa2_eth(E)
> > > > xhci_plat_hcd(E) xhci_hcd(E) usbcore(E) aes_ce_blk(E) crypto_simd(E)
> > > > cryptd(E) aes_ce_cipher(E) ghash_ce(E) gf128mul(E) at803x(E) libaes(E)
> > > > fsl_mc_dpio(E) pcs_lynx(E) rtc_pcf2127(E) sha2_ce(E) phylink(E)
> > > > xgmac_mdio(E) regmap_spi(E) of_mdio(E) sha256_arm64(E)
> > > > i2c_mux_pca954x(E) fixed_phy(E) i2c_mux(E) sha1_ce(E) ptp(E) libphy(E)
> > > > [  714.465131]  pps_core(E) ahci_qoriq(E) libahci_platform(E) nvme(E)
> > > > libahci(E) nvme_core(E) t10_pi(E) libata(E) crc_t10dif(E)
> > > > crct10dif_generic(E) crct10dif_common(E) dwc3(E) scsi_mod(E) udc_core(E)
> > > > roles(E) ulpi(E) sdhci_of_esdhc(E) sdhci_pltfm(E) sdhci(E)
> > > > spi_nxp_fspi(E) i2c_imx(E) fixed(E)
> > > > [  714.465192] CPU: 13 PID: 0 Comm: swapper/13 Tainted: G        W   E
> > > > 5.10.0-rc7-00001-gba98d13279ca #52
> > > > [  714.465196] Hardware name: SolidRun LX2160A Honeycomb (DT)
> > > > [  714.465202] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
> > > > [  714.465207] pc : __arm_lpae_map+0x2d4/0x30c
> > > > [  714.465211] lr : __arm_lpae_map+0x114/0x30c
> > > > [  714.465215] sp : ffff80001006b340
> > > > [  714.465219] x29: ffff80001006b340 x28: 0000002086538003 
> > > > [  714.465227] x27: 0000000000000a20 x26: 0000000000001000 
> > > > [  714.465236] x25: 0000000000000f44 x24: 00000020adf8d000 
> > > > [  714.465245] x23: 0000000000000001 x22: 0000fffffaeca000 
> > > > [  714.465253] x21: 0000000000000003 x20: ffff19b60d64d200 
> > > > [  714.465261] x19: 00000000000000ca x18: 0000000000000000 
> > > > [  714.465270] x17: 0000000000000000 x16: ffffcccb7cf3ca20 
> > > > [  714.465278] x15: 0000000000000000 x14: 0000000000000000 
> > > > [  714.465286] x13: 0000000000000003 x12: 0000000000000010 
> > > > [  714.465294] x11: 0000000000000000 x10: 0000000000000002 
> > > > [  714.465302] x9 : ffffcccb7d5b6e78 x8 : 00000000000001ff 
> > > > [  714.465311] x7 : ffff19b606538650 x6 : ffff19b606538000 
> > > > [  714.465319] x5 : 0000000000000009 x4 : 0000000000000f44 
> > > > [  714.465327] x3 : 0000000000001000 x2 : 00000020adf8d000 
> > > > [  714.465335] x1 : 0000000000000002 x0 : 0000000000000003 
> > > > [  714.465343] Call trace:
> > > > [  714.465348]  __arm_lpae_map+0x2d4/0x30c
> > > > [  714.465353]  __arm_lpae_map+0x114/0x30c
> > > > [  714.465357]  __arm_lpae_map+0x114/0x30c
> > > > [  714.465362]  __arm_lpae_map+0x114/0x30c
> > > > [  714.465366]  arm_lpae_map+0xf4/0x180
> > > > [  714.465373]  arm_smmu_map+0x4c/0xc0
> > > > [  714.465379]  __iommu_map+0x100/0x2bc
> > > > [  714.465385]  iommu_map_atomic+0x20/0x30
> > > > [  714.465391]  __iommu_dma_map+0xb0/0x110
> > > > [  714.465397]  iommu_dma_map_page+0xb8/0x120
> > > > [  714.465404]  dma_map_page_attrs+0x1a8/0x210
> > > > [  714.465413]  __dpaa2_eth_tx+0x384/0xbd0 [fsl_dpaa2_eth]
> > > > [  714.465421]  dpaa2_eth_tx+0x84/0x134 [fsl_dpaa2_eth]
> > > > [  714.465427]  dev_hard_start_xmit+0x10c/0x2b0
> > > > [  714.465433]  sch_direct_xmit+0x1a0/0x550
> > > > [  714.465438]  __qdisc_run+0x140/0x670
> > > > [  714.465443]  __dev_queue_xmit+0x6c4/0xa74
> > > > [  714.465449]  dev_queue_xmit+0x20/0x2c
> > > > [  714.465463]  br_dev_queue_push_xmit+0xc4/0x1a0 [bridge]
> > > > [  714.465476]  br_forward_finish+0xdc/0xf0 [bridge]
> > > > [  714.465489]  __br_forward+0x160/0x1c0 [bridge]
> > > > [  714.465502]  br_forward+0x13c/0x160 [bridge]
> > > > [  714.465514]  br_dev_xmit+0x228/0x3b0 [bridge]
> > > > [  714.465520]  dev_hard_start_xmit+0x10c/0x2b0
> > > > [  714.465526]  __dev_queue_xmit+0x8f0/0xa74
> > > > [  714.465531]  dev_queue_xmit+0x20/0x2c
> > > > [  714.465538]  arp_xmit+0xc0/0xd0
> > > > [  714.465544]  arp_send_dst+0x78/0xa0
> > > > [  714.465550]  arp_solicit+0xf4/0x260
> > > > [  714.465554]  neigh_probe+0x64/0xb0
> > > > [  714.465560]  neigh_timer_handler+0x2f4/0x400
> > > > [  714.465566]  call_timer_fn+0x3c/0x184
> > > > [  714.465572]  __run_timers.part.0+0x2bc/0x370
> > > > [  714.465578]  run_timer_softirq+0x48/0x80
> > > > [  714.465583]  __do_softirq+0x120/0x36c
> > > > [  714.465589]  irq_exit+0xac/0x100
> > > > [  714.465596]  __handle_domain_irq+0x8c/0xf0
> > > > [  714.465600]  gic_handle_irq+0xcc/0x14c
> > > > [  714.465605]  el1_irq+0xc4/0x180
> > > > [  714.465610]  arch_cpu_idle+0x18/0x30
> > > > [  714.465617]  default_idle_call+0x4c/0x180
> > > > [  714.465623]  do_idle+0x238/0x2b0
> > > > [  714.465629]  cpu_startup_entry+0x30/0xa0
> > > > [  714.465636]  secondary_start_kernel+0x134/0x180
> > > > [  714.465640] ---[ end trace a84a7f61b559005f ]---
> > > > 
> > > > 
> > > > Given it is the iommu code that is provoking the warning I should
> > > > probably mention that the board I have requires
> > > > arm-smmu.disable_bypass=0 on the kernel command line in order to boot.
> > > > Also if it matters I am running the latest firmware from Solidrun
> > > > which is based on LSDK-20.04.
> > > > 
> > > 
> > > Hmmm, from what I remember I think I tested this with the smmu bypassed
> > > so that is why I didn't catch it.
> > > 
> > > > Is there any reason for this code not to be working for LX2160A?
> > > 
> > > I wouldn't expect this to be LX2160A specific but rather a bug in the
> > > implementation.. sorry.
> > > 
> > > Let me reproduce it and see if I can get to the bottom of it and I will
> > > get back with some more info.
> > > 
> > 
> > Hi Daniel,
> > 
> > It seems that the dma-unmapping on the SGT buffer was incorrectly done
> > with a zero size since on the Tx path I initialized the improper field.
> > 
> > Could you test the following diff and let me know if you can generate
> > the WARNINGs anymore?
> 
> I fired this up and, with your change, I've not been able to trigger
> the warning with the tests that I used the drive my bisect.
> 

Great, thanks for testing this.

I will take care of sending the fix to -net.

Ioana

> Thanks for the quick response.
> 
> 
> Daniel.
> 
> 
> > 
> > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > @@ -878,7 +878,7 @@ static int dpaa2_eth_build_sg_fd_single_buf(struct dpaa2_eth_priv *priv,
> >         swa = (struct dpaa2_eth_swa *)sgt_buf;
> >         swa->type = DPAA2_ETH_SWA_SINGLE;
> >         swa->single.skb = skb;
> > -       swa->sg.sgt_size = sgt_buf_size;
> > +       swa->single.sgt_size = sgt_buf_size;
> >  
> >         /* Separately map the SGT buffer */
> >         sgt_addr = dma_map_single(dev, sgt_buf, sgt_buf_size, DMA_BIDIRECTIONAL);
> > 
> > 
> > Ioana

Re: [PATCH RESEND net-next 1/2] dpaa2-eth: send a scatter-gather FD instead of realloc-ing

[Jon Nettleton]

On Fri, Dec 11, 2020 at 5:56 PM Ioana Ciornei <ioana.ciornei@nxp.com> wrote:
>
> On Fri, Dec 11, 2020 at 04:29:14PM +0000, Daniel Thompson wrote:
> > On Fri, Dec 11, 2020 at 02:01:28PM +0000, Ioana Ciornei wrote:
> > > On Thu, Dec 10, 2020 at 08:06:36PM +0200, Ioana Ciornei wrote:
> > > > [Added also the netdev mailing list, I haven't heard of linux-netdev
> > > > before but kept it]
> > > >
> > > > On Thu, Dec 10, 2020 at 05:31:56PM +0000, Daniel Thompson wrote:
> > > > > Hi Ioana
> > > >
> > > > Hi Daniel,
> > > >
> > > > >
> > > > > On Mon, Jun 29, 2020 at 06:47:11PM +0000, Ioana Ciornei wrote:
> > > > > > Instead of realloc-ing the skb on the Tx path when the provided headroom
> > > > > > is smaller than the HW requirements, create a Scatter/Gather frame
> > > > > > descriptor with only one entry.
> > > > > >
> > > > > > Remove the '[drv] tx realloc frames' counter exposed previously through
> > > > > > ethtool since it is no longer used.
> > > > > >
> > > > > > Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> > > > > > ---
> > > > >
> > > > > I've been chasing down a networking regression on my LX2160A board
> > > > > (Honeycomb LX2K based on CEx7 LX2160A COM) that first appeared in v5.9.
> > > > >
> > > > > It makes the board unreliable opening outbound connections meaning
> > > > > things like `apt update` or `git fetch` often can't open the connection.
> > > > > It does not happen all the time but is sufficient to make the boards
> > > > > built-in networking useless for workstation use.
> > > > >
> > > > > The problem is strongly linked to warnings in the logs so I used the
> > > > > warnings to bisect down to locate the cause of the regression and it
> > > > > pinpointed this patch. I have confirmed that in both v5.9 and v5.10-rc7
> > > > > that reverting this patch (and fixing up the merge issues) fixes the
> > > > > regression and the warnings stop appearing.
> > > > >
> > > > > A typical example of the warning is below (io-pgtable-arm.c:281 is an
> > > > > error path that I guess would cause dma_map_page_attrs() to return
> > > > > an error):
> > > > >
> > > > > [  714.464927] WARNING: CPU: 13 PID: 0 at
> > > > > drivers/iommu/io-pgtable-arm.c:281 __arm_lpae_map+0x2d4/0x30c
> > > > > [  714.464930] Modules linked in: snd_seq_dummy(E) snd_hrtimer(E)
> > > > > snd_seq(E) snd_seq_device(E) snd_timer(E) snd(E) soundcore(E) bridge(E)
> > > > > stp(E) llc(E) rfkill(E) caam_jr(E) crypto_engine(E) rng_core(E)
> > > > > joydev(E) evdev(E) dpaa2_caam(E) caamhash_desc(E) caamalg_desc(E)
> > > > > authenc(E) libdes(E) dpaa2_console(E) ofpart(E) caam(E) sg(E) error(E)
> > > > > lm90(E) at24(E) spi_nor(E) mtd(E) sbsa_gwdt(E) qoriq_thermal(E)
> > > > > layerscape_edac_mod(E) qoriq_cpufreq(E) drm(E) fuse(E) configfs(E)
> > > > > ip_tables(E) x_tables(E) autofs4(E) ext4(E) crc32c_generic(E) crc16(E)
> > > > > mbcache(E) jbd2(E) hid_generic(E) usbhid(E) hid(E) dm_crypt(E) dm_mod(E)
> > > > > sd_mod(E) fsl_dpaa2_ptp(E) ptp_qoriq(E) fsl_dpaa2_eth(E)
> > > > > xhci_plat_hcd(E) xhci_hcd(E) usbcore(E) aes_ce_blk(E) crypto_simd(E)
> > > > > cryptd(E) aes_ce_cipher(E) ghash_ce(E) gf128mul(E) at803x(E) libaes(E)
> > > > > fsl_mc_dpio(E) pcs_lynx(E) rtc_pcf2127(E) sha2_ce(E) phylink(E)
> > > > > xgmac_mdio(E) regmap_spi(E) of_mdio(E) sha256_arm64(E)
> > > > > i2c_mux_pca954x(E) fixed_phy(E) i2c_mux(E) sha1_ce(E) ptp(E) libphy(E)
> > > > > [  714.465131]  pps_core(E) ahci_qoriq(E) libahci_platform(E) nvme(E)
> > > > > libahci(E) nvme_core(E) t10_pi(E) libata(E) crc_t10dif(E)
> > > > > crct10dif_generic(E) crct10dif_common(E) dwc3(E) scsi_mod(E) udc_core(E)
> > > > > roles(E) ulpi(E) sdhci_of_esdhc(E) sdhci_pltfm(E) sdhci(E)
> > > > > spi_nxp_fspi(E) i2c_imx(E) fixed(E)
> > > > > [  714.465192] CPU: 13 PID: 0 Comm: swapper/13 Tainted: G        W   E
> > > > > 5.10.0-rc7-00001-gba98d13279ca #52
> > > > > [  714.465196] Hardware name: SolidRun LX2160A Honeycomb (DT)
> > > > > [  714.465202] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
> > > > > [  714.465207] pc : __arm_lpae_map+0x2d4/0x30c
> > > > > [  714.465211] lr : __arm_lpae_map+0x114/0x30c
> > > > > [  714.465215] sp : ffff80001006b340
> > > > > [  714.465219] x29: ffff80001006b340 x28: 0000002086538003
> > > > > [  714.465227] x27: 0000000000000a20 x26: 0000000000001000
> > > > > [  714.465236] x25: 0000000000000f44 x24: 00000020adf8d000
> > > > > [  714.465245] x23: 0000000000000001 x22: 0000fffffaeca000
> > > > > [  714.465253] x21: 0000000000000003 x20: ffff19b60d64d200
> > > > > [  714.465261] x19: 00000000000000ca x18: 0000000000000000
> > > > > [  714.465270] x17: 0000000000000000 x16: ffffcccb7cf3ca20
> > > > > [  714.465278] x15: 0000000000000000 x14: 0000000000000000
> > > > > [  714.465286] x13: 0000000000000003 x12: 0000000000000010
> > > > > [  714.465294] x11: 0000000000000000 x10: 0000000000000002
> > > > > [  714.465302] x9 : ffffcccb7d5b6e78 x8 : 00000000000001ff
> > > > > [  714.465311] x7 : ffff19b606538650 x6 : ffff19b606538000
> > > > > [  714.465319] x5 : 0000000000000009 x4 : 0000000000000f44
> > > > > [  714.465327] x3 : 0000000000001000 x2 : 00000020adf8d000
> > > > > [  714.465335] x1 : 0000000000000002 x0 : 0000000000000003
> > > > > [  714.465343] Call trace:
> > > > > [  714.465348]  __arm_lpae_map+0x2d4/0x30c
> > > > > [  714.465353]  __arm_lpae_map+0x114/0x30c
> > > > > [  714.465357]  __arm_lpae_map+0x114/0x30c
> > > > > [  714.465362]  __arm_lpae_map+0x114/0x30c
> > > > > [  714.465366]  arm_lpae_map+0xf4/0x180
> > > > > [  714.465373]  arm_smmu_map+0x4c/0xc0
> > > > > [  714.465379]  __iommu_map+0x100/0x2bc
> > > > > [  714.465385]  iommu_map_atomic+0x20/0x30
> > > > > [  714.465391]  __iommu_dma_map+0xb0/0x110
> > > > > [  714.465397]  iommu_dma_map_page+0xb8/0x120
> > > > > [  714.465404]  dma_map_page_attrs+0x1a8/0x210
> > > > > [  714.465413]  __dpaa2_eth_tx+0x384/0xbd0 [fsl_dpaa2_eth]
> > > > > [  714.465421]  dpaa2_eth_tx+0x84/0x134 [fsl_dpaa2_eth]
> > > > > [  714.465427]  dev_hard_start_xmit+0x10c/0x2b0
> > > > > [  714.465433]  sch_direct_xmit+0x1a0/0x550
> > > > > [  714.465438]  __qdisc_run+0x140/0x670
> > > > > [  714.465443]  __dev_queue_xmit+0x6c4/0xa74
> > > > > [  714.465449]  dev_queue_xmit+0x20/0x2c
> > > > > [  714.465463]  br_dev_queue_push_xmit+0xc4/0x1a0 [bridge]
> > > > > [  714.465476]  br_forward_finish+0xdc/0xf0 [bridge]
> > > > > [  714.465489]  __br_forward+0x160/0x1c0 [bridge]
> > > > > [  714.465502]  br_forward+0x13c/0x160 [bridge]
> > > > > [  714.465514]  br_dev_xmit+0x228/0x3b0 [bridge]
> > > > > [  714.465520]  dev_hard_start_xmit+0x10c/0x2b0
> > > > > [  714.465526]  __dev_queue_xmit+0x8f0/0xa74
> > > > > [  714.465531]  dev_queue_xmit+0x20/0x2c
> > > > > [  714.465538]  arp_xmit+0xc0/0xd0
> > > > > [  714.465544]  arp_send_dst+0x78/0xa0
> > > > > [  714.465550]  arp_solicit+0xf4/0x260
> > > > > [  714.465554]  neigh_probe+0x64/0xb0
> > > > > [  714.465560]  neigh_timer_handler+0x2f4/0x400
> > > > > [  714.465566]  call_timer_fn+0x3c/0x184
> > > > > [  714.465572]  __run_timers.part.0+0x2bc/0x370
> > > > > [  714.465578]  run_timer_softirq+0x48/0x80
> > > > > [  714.465583]  __do_softirq+0x120/0x36c
> > > > > [  714.465589]  irq_exit+0xac/0x100
> > > > > [  714.465596]  __handle_domain_irq+0x8c/0xf0
> > > > > [  714.465600]  gic_handle_irq+0xcc/0x14c
> > > > > [  714.465605]  el1_irq+0xc4/0x180
> > > > > [  714.465610]  arch_cpu_idle+0x18/0x30
> > > > > [  714.465617]  default_idle_call+0x4c/0x180
> > > > > [  714.465623]  do_idle+0x238/0x2b0
> > > > > [  714.465629]  cpu_startup_entry+0x30/0xa0
> > > > > [  714.465636]  secondary_start_kernel+0x134/0x180
> > > > > [  714.465640] ---[ end trace a84a7f61b559005f ]---
> > > > >
> > > > >
> > > > > Given it is the iommu code that is provoking the warning I should
> > > > > probably mention that the board I have requires
> > > > > arm-smmu.disable_bypass=0 on the kernel command line in order to boot.
> > > > > Also if it matters I am running the latest firmware from Solidrun
> > > > > which is based on LSDK-20.04.
> > > > >
> > > >
> > > > Hmmm, from what I remember I think I tested this with the smmu bypassed
> > > > so that is why I didn't catch it.
> > > >
> > > > > Is there any reason for this code not to be working for LX2160A?
> > > >
> > > > I wouldn't expect this to be LX2160A specific but rather a bug in the
> > > > implementation.. sorry.
> > > >
> > > > Let me reproduce it and see if I can get to the bottom of it and I will
> > > > get back with some more info.
> > > >
> > >
> > > Hi Daniel,
> > >
> > > It seems that the dma-unmapping on the SGT buffer was incorrectly done
> > > with a zero size since on the Tx path I initialized the improper field.
> > >
> > > Could you test the following diff and let me know if you can generate
> > > the WARNINGs anymore?
> >
> > I fired this up and, with your change, I've not been able to trigger
> > the warning with the tests that I used the drive my bisect.
> >
>
> Great, thanks for testing this.
>
> I will take care of sending the fix to -net.
>
> Ioana

Ioana,

Please CC me when you send the patch to -net, I will put my Tested-by: on it.

Thanks
Jon

>
> > Thanks for the quick response.
> >
> >
> > Daniel.
> >
> >
> > >
> > > --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > > +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
> > > @@ -878,7 +878,7 @@ static int dpaa2_eth_build_sg_fd_single_buf(struct dpaa2_eth_priv *priv,
> > >         swa = (struct dpaa2_eth_swa *)sgt_buf;
> > >         swa->type = DPAA2_ETH_SWA_SINGLE;
> > >         swa->single.skb = skb;
> > > -       swa->sg.sgt_size = sgt_buf_size;
> > > +       swa->single.sgt_size = sgt_buf_size;
> > >
> > >         /* Separately map the SGT buffer */
> > >         sgt_addr = dma_map_single(dev, sgt_buf, sgt_buf_size, DMA_BIDIRECTIONAL);
> > >
> > >
> > > Ioana

Re: [PATCH RESEND net-next 1/2] dpaa2-eth: send a scatter-gather FD instead of realloc-ing

[Ioana Ciornei]

On Sat, Dec 12, 2020 at 04:58:56PM +0100, Jon Nettleton wrote:
> On Fri, Dec 11, 2020 at 5:56 PM Ioana Ciornei <ioana.ciornei@nxp.com> wrote:
> >
> > On Fri, Dec 11, 2020 at 04:29:14PM +0000, Daniel Thompson wrote:
> > > On Fri, Dec 11, 2020 at 02:01:28PM +0000, Ioana Ciornei wrote:
> > > > On Thu, Dec 10, 2020 at 08:06:36PM +0200, Ioana Ciornei wrote:
> > > > > [Added also the netdev mailing list, I haven't heard of linux-netdev
> > > > > before but kept it]
> > > > >
> > > > > On Thu, Dec 10, 2020 at 05:31:56PM +0000, Daniel Thompson wrote:
> > > > > > Hi Ioana
> > > > >
> > > > > Hi Daniel,
> > > > >
> > > > > >
> > > > > > On Mon, Jun 29, 2020 at 06:47:11PM +0000, Ioana Ciornei wrote:
> > > > > > > Instead of realloc-ing the skb on the Tx path when the provided headroom
> > > > > > > is smaller than the HW requirements, create a Scatter/Gather frame
> > > > > > > descriptor with only one entry.
> > > > > > >
> > > > > > > Remove the '[drv] tx realloc frames' counter exposed previously through
> > > > > > > ethtool since it is no longer used.
> > > > > > >
> > > > > > > Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> > > > > > > ---
> > > > > >
> > > > > > I've been chasing down a networking regression on my LX2160A board
> > > > > > (Honeycomb LX2K based on CEx7 LX2160A COM) that first appeared in v5.9.
> > > > > >
> > > > > > It makes the board unreliable opening outbound connections meaning
> > > > > > things like `apt update` or `git fetch` often can't open the connection.
> > > > > > It does not happen all the time but is sufficient to make the boards
> > > > > > built-in networking useless for workstation use.
> > > > > >
> > > > > > The problem is strongly linked to warnings in the logs so I used the
> > > > > > warnings to bisect down to locate the cause of the regression and it
> > > > > > pinpointed this patch. I have confirmed that in both v5.9 and v5.10-rc7
> > > > > > that reverting this patch (and fixing up the merge issues) fixes the
> > > > > > regression and the warnings stop appearing.
> > > > > >
> > > > > > A typical example of the warning is below (io-pgtable-arm.c:281 is an
> > > > > > error path that I guess would cause dma_map_page_attrs() to return
> > > > > > an error):
> > > > > >
> > > > > > [  714.464927] WARNING: CPU: 13 PID: 0 at
> > > > > > drivers/iommu/io-pgtable-arm.c:281 __arm_lpae_map+0x2d4/0x30c
> > > > > > [  714.464930] Modules linked in: snd_seq_dummy(E) snd_hrtimer(E)
> > > > > > snd_seq(E) snd_seq_device(E) snd_timer(E) snd(E) soundcore(E) bridge(E)
> > > > > > stp(E) llc(E) rfkill(E) caam_jr(E) crypto_engine(E) rng_core(E)
> > > > > > joydev(E) evdev(E) dpaa2_caam(E) caamhash_desc(E) caamalg_desc(E)
> > > > > > authenc(E) libdes(E) dpaa2_console(E) ofpart(E) caam(E) sg(E) error(E)
> > > > > > lm90(E) at24(E) spi_nor(E) mtd(E) sbsa_gwdt(E) qoriq_thermal(E)
> > > > > > layerscape_edac_mod(E) qoriq_cpufreq(E) drm(E) fuse(E) configfs(E)
> > > > > > ip_tables(E) x_tables(E) autofs4(E) ext4(E) crc32c_generic(E) crc16(E)
> > > > > > mbcache(E) jbd2(E) hid_generic(E) usbhid(E) hid(E) dm_crypt(E) dm_mod(E)
> > > > > > sd_mod(E) fsl_dpaa2_ptp(E) ptp_qoriq(E) fsl_dpaa2_eth(E)
> > > > > > xhci_plat_hcd(E) xhci_hcd(E) usbcore(E) aes_ce_blk(E) crypto_simd(E)
> > > > > > cryptd(E) aes_ce_cipher(E) ghash_ce(E) gf128mul(E) at803x(E) libaes(E)
> > > > > > fsl_mc_dpio(E) pcs_lynx(E) rtc_pcf2127(E) sha2_ce(E) phylink(E)
> > > > > > xgmac_mdio(E) regmap_spi(E) of_mdio(E) sha256_arm64(E)
> > > > > > i2c_mux_pca954x(E) fixed_phy(E) i2c_mux(E) sha1_ce(E) ptp(E) libphy(E)
> > > > > > [  714.465131]  pps_core(E) ahci_qoriq(E) libahci_platform(E) nvme(E)
> > > > > > libahci(E) nvme_core(E) t10_pi(E) libata(E) crc_t10dif(E)
> > > > > > crct10dif_generic(E) crct10dif_common(E) dwc3(E) scsi_mod(E) udc_core(E)
> > > > > > roles(E) ulpi(E) sdhci_of_esdhc(E) sdhci_pltfm(E) sdhci(E)
> > > > > > spi_nxp_fspi(E) i2c_imx(E) fixed(E)
> > > > > > [  714.465192] CPU: 13 PID: 0 Comm: swapper/13 Tainted: G        W   E
> > > > > > 5.10.0-rc7-00001-gba98d13279ca #52
> > > > > > [  714.465196] Hardware name: SolidRun LX2160A Honeycomb (DT)
> > > > > > [  714.465202] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
> > > > > > [  714.465207] pc : __arm_lpae_map+0x2d4/0x30c
> > > > > > [  714.465211] lr : __arm_lpae_map+0x114/0x30c
> > > > > > [  714.465215] sp : ffff80001006b340
> > > > > > [  714.465219] x29: ffff80001006b340 x28: 0000002086538003
> > > > > > [  714.465227] x27: 0000000000000a20 x26: 0000000000001000
> > > > > > [  714.465236] x25: 0000000000000f44 x24: 00000020adf8d000
> > > > > > [  714.465245] x23: 0000000000000001 x22: 0000fffffaeca000
> > > > > > [  714.465253] x21: 0000000000000003 x20: ffff19b60d64d200
> > > > > > [  714.465261] x19: 00000000000000ca x18: 0000000000000000
> > > > > > [  714.465270] x17: 0000000000000000 x16: ffffcccb7cf3ca20
> > > > > > [  714.465278] x15: 0000000000000000 x14: 0000000000000000
> > > > > > [  714.465286] x13: 0000000000000003 x12: 0000000000000010
> > > > > > [  714.465294] x11: 0000000000000000 x10: 0000000000000002
> > > > > > [  714.465302] x9 : ffffcccb7d5b6e78 x8 : 00000000000001ff
> > > > > > [  714.465311] x7 : ffff19b606538650 x6 : ffff19b606538000
> > > > > > [  714.465319] x5 : 0000000000000009 x4 : 0000000000000f44
> > > > > > [  714.465327] x3 : 0000000000001000 x2 : 00000020adf8d000
> > > > > > [  714.465335] x1 : 0000000000000002 x0 : 0000000000000003
> > > > > > [  714.465343] Call trace:
> > > > > > [  714.465348]  __arm_lpae_map+0x2d4/0x30c
> > > > > > [  714.465353]  __arm_lpae_map+0x114/0x30c
> > > > > > [  714.465357]  __arm_lpae_map+0x114/0x30c
> > > > > > [  714.465362]  __arm_lpae_map+0x114/0x30c
> > > > > > [  714.465366]  arm_lpae_map+0xf4/0x180
> > > > > > [  714.465373]  arm_smmu_map+0x4c/0xc0
> > > > > > [  714.465379]  __iommu_map+0x100/0x2bc
> > > > > > [  714.465385]  iommu_map_atomic+0x20/0x30
> > > > > > [  714.465391]  __iommu_dma_map+0xb0/0x110
> > > > > > [  714.465397]  iommu_dma_map_page+0xb8/0x120
> > > > > > [  714.465404]  dma_map_page_attrs+0x1a8/0x210
> > > > > > [  714.465413]  __dpaa2_eth_tx+0x384/0xbd0 [fsl_dpaa2_eth]
> > > > > > [  714.465421]  dpaa2_eth_tx+0x84/0x134 [fsl_dpaa2_eth]
> > > > > > [  714.465427]  dev_hard_start_xmit+0x10c/0x2b0
> > > > > > [  714.465433]  sch_direct_xmit+0x1a0/0x550
> > > > > > [  714.465438]  __qdisc_run+0x140/0x670
> > > > > > [  714.465443]  __dev_queue_xmit+0x6c4/0xa74
> > > > > > [  714.465449]  dev_queue_xmit+0x20/0x2c
> > > > > > [  714.465463]  br_dev_queue_push_xmit+0xc4/0x1a0 [bridge]
> > > > > > [  714.465476]  br_forward_finish+0xdc/0xf0 [bridge]
> > > > > > [  714.465489]  __br_forward+0x160/0x1c0 [bridge]
> > > > > > [  714.465502]  br_forward+0x13c/0x160 [bridge]
> > > > > > [  714.465514]  br_dev_xmit+0x228/0x3b0 [bridge]
> > > > > > [  714.465520]  dev_hard_start_xmit+0x10c/0x2b0
> > > > > > [  714.465526]  __dev_queue_xmit+0x8f0/0xa74
> > > > > > [  714.465531]  dev_queue_xmit+0x20/0x2c
> > > > > > [  714.465538]  arp_xmit+0xc0/0xd0
> > > > > > [  714.465544]  arp_send_dst+0x78/0xa0
> > > > > > [  714.465550]  arp_solicit+0xf4/0x260
> > > > > > [  714.465554]  neigh_probe+0x64/0xb0
> > > > > > [  714.465560]  neigh_timer_handler+0x2f4/0x400
> > > > > > [  714.465566]  call_timer_fn+0x3c/0x184
> > > > > > [  714.465572]  __run_timers.part.0+0x2bc/0x370
> > > > > > [  714.465578]  run_timer_softirq+0x48/0x80
> > > > > > [  714.465583]  __do_softirq+0x120/0x36c
> > > > > > [  714.465589]  irq_exit+0xac/0x100
> > > > > > [  714.465596]  __handle_domain_irq+0x8c/0xf0
> > > > > > [  714.465600]  gic_handle_irq+0xcc/0x14c
> > > > > > [  714.465605]  el1_irq+0xc4/0x180
> > > > > > [  714.465610]  arch_cpu_idle+0x18/0x30
> > > > > > [  714.465617]  default_idle_call+0x4c/0x180
> > > > > > [  714.465623]  do_idle+0x238/0x2b0
> > > > > > [  714.465629]  cpu_startup_entry+0x30/0xa0
> > > > > > [  714.465636]  secondary_start_kernel+0x134/0x180
> > > > > > [  714.465640] ---[ end trace a84a7f61b559005f ]---
> > > > > >
> > > > > >
> > > > > > Given it is the iommu code that is provoking the warning I should
> > > > > > probably mention that the board I have requires
> > > > > > arm-smmu.disable_bypass=0 on the kernel command line in order to boot.
> > > > > > Also if it matters I am running the latest firmware from Solidrun
> > > > > > which is based on LSDK-20.04.
> > > > > >
> > > > >
> > > > > Hmmm, from what I remember I think I tested this with the smmu bypassed
> > > > > so that is why I didn't catch it.
> > > > >
> > > > > > Is there any reason for this code not to be working for LX2160A?
> > > > >
> > > > > I wouldn't expect this to be LX2160A specific but rather a bug in the
> > > > > implementation.. sorry.
> > > > >
> > > > > Let me reproduce it and see if I can get to the bottom of it and I will
> > > > > get back with some more info.
> > > > >
> > > >
> > > > Hi Daniel,
> > > >
> > > > It seems that the dma-unmapping on the SGT buffer was incorrectly done
> > > > with a zero size since on the Tx path I initialized the improper field.
> > > >
> > > > Could you test the following diff and let me know if you can generate
> > > > the WARNINGs anymore?
> > >
> > > I fired this up and, with your change, I've not been able to trigger
> > > the warning with the tests that I used the drive my bisect.
> > >
> >
> > Great, thanks for testing this.
> >
> > I will take care of sending the fix to -net.
> >
> > Ioana
> 
> Ioana,
> 
> Please CC me when you send the patch to -net, I will put my Tested-by: on it.
> 

Hi Jon,

I sent out the patch yesterday. You are also copied.

https://lore.kernel.org/netdev/20201211171607.108034-1-ciorneiioana@gmail.com/


Ioana

[PATCH RESEND net-next 0/2] dpaa2-eth: send a scatter-gather FD instead of realloc-ing

[Ioana Ciornei]

This patch set changes the behaviour in case the Tx path is confroted
with an SKB with insufficient headroom for our hardware necessities (SW
annotation area). In the first patch, instead of realloc-ing the SKB we
now send a S/G frames descriptor while the second one adds a new
software held counter to account for for these types of frames.

Ioana Ciornei (2):
  dpaa2-eth: send a scatter-gather FD instead of realloc-ing
  dpaa2-eth: add software counter for Tx frames converted to S/G

 .../freescale/dpaa2/dpaa2-eth-debugfs.c       |   4 +-
 .../net/ethernet/freescale/dpaa2/dpaa2-eth.c  | 179 +++++++++++++++---
 .../net/ethernet/freescale/dpaa2/dpaa2-eth.h  |  12 +-
 .../ethernet/freescale/dpaa2/dpaa2-ethtool.c  |   3 +-
 4 files changed, 166 insertions(+), 32 deletions(-)

-- 
2.25.1

[PATCH RESEND net-next 1/2] dpaa2-eth: send a scatter-gather FD instead of realloc-ing

[Ioana Ciornei]

Instead of realloc-ing the skb on the Tx path when the provided headroom
is smaller than the HW requirements, create a Scatter/Gather frame
descriptor with only one entry.

Remove the '[drv] tx realloc frames' counter exposed previously through
ethtool since it is no longer used.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
---
 .../freescale/dpaa2/dpaa2-eth-debugfs.c       |   7 +-
 .../net/ethernet/freescale/dpaa2/dpaa2-eth.c  | 177 +++++++++++++++---
 .../net/ethernet/freescale/dpaa2/dpaa2-eth.h  |   9 +-
 .../ethernet/freescale/dpaa2/dpaa2-ethtool.c  |   1 -
 4 files changed, 160 insertions(+), 34 deletions(-)

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c
index 2880ca02d7e7..5cb357c74dec 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c
@@ -19,14 +19,14 @@ static int dpaa2_dbg_cpu_show(struct seq_file *file, void *offset)
 	int i;
 
 	seq_printf(file, "Per-CPU stats for %s\n", priv->net_dev->name);
-	seq_printf(file, "%s%16s%16s%16s%16s%16s%16s%16s%16s%16s\n",
+	seq_printf(file, "%s%16s%16s%16s%16s%16s%16s%16s%16s\n",
 		   "CPU", "Rx", "Rx Err", "Rx SG", "Tx", "Tx Err", "Tx conf",
-		   "Tx SG", "Tx realloc", "Enq busy");
+		   "Tx SG", "Enq busy");
 
 	for_each_online_cpu(i) {
 		stats = per_cpu_ptr(priv->percpu_stats, i);
 		extras = per_cpu_ptr(priv->percpu_extras, i);
-		seq_printf(file, "%3d%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu\n",
+		seq_printf(file, "%3d%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu\n",
 			   i,
 			   stats->rx_packets,
 			   stats->rx_errors,
@@ -35,7 +35,6 @@ static int dpaa2_dbg_cpu_show(struct seq_file *file, void *offset)
 			   stats->tx_errors,
 			   extras->tx_conf_frames,
 			   extras->tx_sg_frames,
-			   extras->tx_reallocs,
 			   extras->tx_portal_busy);
 	}
 
diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index 712bbfdbe7d7..4a264b75c035 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
@@ -685,6 +685,86 @@ static int build_sg_fd(struct dpaa2_eth_priv *priv,
 	return err;
 }
 
+/* Create a SG frame descriptor based on a linear skb.
+ *
+ * This function is used on the Tx path when the skb headroom is not large
+ * enough for the HW requirements, thus instead of realloc-ing the skb we
+ * create a SG frame descriptor with only one entry.
+ */
+static int build_sg_fd_single_buf(struct dpaa2_eth_priv *priv,
+				  struct sk_buff *skb,
+				  struct dpaa2_fd *fd)
+{
+	struct device *dev = priv->net_dev->dev.parent;
+	struct dpaa2_eth_sgt_cache *sgt_cache;
+	struct dpaa2_sg_entry *sgt;
+	struct dpaa2_eth_swa *swa;
+	dma_addr_t addr, sgt_addr;
+	void *sgt_buf = NULL;
+	int sgt_buf_size;
+	int err;
+
+	/* Prepare the HW SGT structure */
+	sgt_cache = this_cpu_ptr(priv->sgt_cache);
+	sgt_buf_size = priv->tx_data_offset + sizeof(struct dpaa2_sg_entry);
+
+	if (sgt_cache->count == 0)
+		sgt_buf = kzalloc(sgt_buf_size + DPAA2_ETH_TX_BUF_ALIGN,
+				  GFP_ATOMIC);
+	else
+		sgt_buf = sgt_cache->buf[--sgt_cache->count];
+	if (unlikely(!sgt_buf))
+		return -ENOMEM;
+
+	sgt_buf = PTR_ALIGN(sgt_buf, DPAA2_ETH_TX_BUF_ALIGN);
+	sgt = (struct dpaa2_sg_entry *)(sgt_buf + priv->tx_data_offset);
+
+	addr = dma_map_single(dev, skb->data, skb->len, DMA_BIDIRECTIONAL);
+	if (unlikely(dma_mapping_error(dev, addr))) {
+		err = -ENOMEM;
+		goto data_map_failed;
+	}
+
+	/* Fill in the HW SGT structure */
+	dpaa2_sg_set_addr(sgt, addr);
+	dpaa2_sg_set_len(sgt, skb->len);
+	dpaa2_sg_set_final(sgt, true);
+
+	/* Store the skb backpointer in the SGT buffer */
+	swa = (struct dpaa2_eth_swa *)sgt_buf;
+	swa->type = DPAA2_ETH_SWA_SINGLE;
+	swa->single.skb = skb;
+	swa->sg.sgt_size = sgt_buf_size;
+
+	/* Separately map the SGT buffer */
+	sgt_addr = dma_map_single(dev, sgt_buf, sgt_buf_size, DMA_BIDIRECTIONAL);
+	if (unlikely(dma_mapping_error(dev, sgt_addr))) {
+		err = -ENOMEM;
+		goto sgt_map_failed;
+	}
+
+	dpaa2_fd_set_offset(fd, priv->tx_data_offset);
+	dpaa2_fd_set_format(fd, dpaa2_fd_sg);
+	dpaa2_fd_set_addr(fd, sgt_addr);
+	dpaa2_fd_set_len(fd, skb->len);
+	dpaa2_fd_set_ctrl(fd, FD_CTRL_PTA);
+
+	if (priv->tx_tstamp && skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)
+		enable_tx_tstamp(fd, sgt_buf);
+
+	return 0;
+
+sgt_map_failed:
+	dma_unmap_single(dev, addr, skb->len, DMA_BIDIRECTIONAL);
+data_map_failed:
+	if (sgt_cache->count >= DPAA2_ETH_SGT_CACHE_SIZE)
+		kfree(sgt_buf);
+	else
+		sgt_cache->buf[sgt_cache->count++] = sgt_buf;
+
+	return err;
+}
+
 /* Create a frame descriptor based on a linear skb */
 static int build_single_fd(struct dpaa2_eth_priv *priv,
 			   struct sk_buff *skb,
@@ -743,13 +823,16 @@ static void free_tx_fd(const struct dpaa2_eth_priv *priv,
 		       const struct dpaa2_fd *fd, bool in_napi)
 {
 	struct device *dev = priv->net_dev->dev.parent;
-	dma_addr_t fd_addr;
+	dma_addr_t fd_addr, sg_addr;
 	struct sk_buff *skb = NULL;
 	unsigned char *buffer_start;
 	struct dpaa2_eth_swa *swa;
 	u8 fd_format = dpaa2_fd_get_format(fd);
 	u32 fd_len = dpaa2_fd_get_len(fd);
 
+	struct dpaa2_eth_sgt_cache *sgt_cache;
+	struct dpaa2_sg_entry *sgt;
+
 	fd_addr = dpaa2_fd_get_addr(fd);
 	buffer_start = dpaa2_iova_to_virt(priv->iommu_domain, fd_addr);
 	swa = (struct dpaa2_eth_swa *)buffer_start;
@@ -769,16 +852,29 @@ static void free_tx_fd(const struct dpaa2_eth_priv *priv,
 					 DMA_BIDIRECTIONAL);
 		}
 	} else if (fd_format == dpaa2_fd_sg) {
-		skb = swa->sg.skb;
+		if (swa->type == DPAA2_ETH_SWA_SG) {
+			skb = swa->sg.skb;
+
+			/* Unmap the scatterlist */
+			dma_unmap_sg(dev, swa->sg.scl, swa->sg.num_sg,
+				     DMA_BIDIRECTIONAL);
+			kfree(swa->sg.scl);
 
-		/* Unmap the scatterlist */
-		dma_unmap_sg(dev, swa->sg.scl, swa->sg.num_sg,
-			     DMA_BIDIRECTIONAL);
-		kfree(swa->sg.scl);
+			/* Unmap the SGT buffer */
+			dma_unmap_single(dev, fd_addr, swa->sg.sgt_size,
+					 DMA_BIDIRECTIONAL);
+		} else {
+			skb = swa->single.skb;
 
-		/* Unmap the SGT buffer */
-		dma_unmap_single(dev, fd_addr, swa->sg.sgt_size,
-				 DMA_BIDIRECTIONAL);
+			/* Unmap the SGT Buffer */
+			dma_unmap_single(dev, fd_addr, swa->single.sgt_size,
+					 DMA_BIDIRECTIONAL);
+
+			sgt = (struct dpaa2_sg_entry *)(buffer_start +
+							priv->tx_data_offset);
+			sg_addr = dpaa2_sg_get_addr(sgt);
+			dma_unmap_single(dev, sg_addr, skb->len, DMA_BIDIRECTIONAL);
+		}
 	} else {
 		netdev_dbg(priv->net_dev, "Invalid FD format\n");
 		return;
@@ -808,8 +904,17 @@ static void free_tx_fd(const struct dpaa2_eth_priv *priv,
 	}
 
 	/* Free SGT buffer allocated on tx */
-	if (fd_format != dpaa2_fd_single)
-		skb_free_frag(buffer_start);
+	if (fd_format != dpaa2_fd_single) {
+		sgt_cache = this_cpu_ptr(priv->sgt_cache);
+		if (swa->type == DPAA2_ETH_SWA_SG) {
+			skb_free_frag(buffer_start);
+		} else {
+			if (sgt_cache->count >= DPAA2_ETH_SGT_CACHE_SIZE)
+				kfree(buffer_start);
+			else
+				sgt_cache->buf[sgt_cache->count++] = buffer_start;
+		}
+	}
 
 	/* Move on with skb release */
 	napi_consume_skb(skb, in_napi);
@@ -833,22 +938,6 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
 	percpu_extras = this_cpu_ptr(priv->percpu_extras);
 
 	needed_headroom = dpaa2_eth_needed_headroom(priv, skb);
-	if (skb_headroom(skb) < needed_headroom) {
-		struct sk_buff *ns;
-
-		ns = skb_realloc_headroom(skb, needed_headroom);
-		if (unlikely(!ns)) {
-			percpu_stats->tx_dropped++;
-			goto err_alloc_headroom;
-		}
-		percpu_extras->tx_reallocs++;
-
-		if (skb->sk)
-			skb_set_owner_w(ns, skb->sk);
-
-		dev_kfree_skb(skb);
-		skb = ns;
-	}
 
 	/* We'll be holding a back-reference to the skb until Tx Confirmation;
 	 * we don't want that overwritten by a concurrent Tx with a cloned skb.
@@ -867,6 +956,10 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
 		err = build_sg_fd(priv, skb, &fd);
 		percpu_extras->tx_sg_frames++;
 		percpu_extras->tx_sg_bytes += skb->len;
+	} else if (skb_headroom(skb) < needed_headroom) {
+		err = build_sg_fd_single_buf(priv, skb, &fd);
+		percpu_extras->tx_sg_frames++;
+		percpu_extras->tx_sg_bytes += skb->len;
 	} else {
 		err = build_single_fd(priv, skb, &fd);
 	}
@@ -924,7 +1017,6 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
 	return NETDEV_TX_OK;
 
 err_build_fd:
-err_alloc_headroom:
 	dev_kfree_skb(skb);
 
 	return NETDEV_TX_OK;
@@ -1161,6 +1253,22 @@ static int refill_pool(struct dpaa2_eth_priv *priv,
 	return 0;
 }
 
+static void dpaa2_eth_sgt_cache_drain(struct dpaa2_eth_priv *priv)
+{
+	struct dpaa2_eth_sgt_cache *sgt_cache;
+	u16 count;
+	int k, i;
+
+	for_each_online_cpu(k) {
+		sgt_cache = per_cpu_ptr(priv->sgt_cache, k);
+		count = sgt_cache->count;
+
+		for (i = 0; i < count; i++)
+			kfree(sgt_cache->buf[i]);
+		sgt_cache->count = 0;
+	}
+}
+
 static int pull_channel(struct dpaa2_eth_channel *ch)
 {
 	int err;
@@ -1562,6 +1670,9 @@ static int dpaa2_eth_stop(struct net_device *net_dev)
 	/* Empty the buffer pool */
 	drain_pool(priv);
 
+	/* Empty the Scatter-Gather Buffer cache */
+	dpaa2_eth_sgt_cache_drain(priv);
+
 	return 0;
 }
 
@@ -3846,6 +3957,13 @@ static int dpaa2_eth_probe(struct fsl_mc_device *dpni_dev)
 		goto err_alloc_percpu_extras;
 	}
 
+	priv->sgt_cache = alloc_percpu(*priv->sgt_cache);
+	if (!priv->sgt_cache) {
+		dev_err(dev, "alloc_percpu(sgt_cache) failed\n");
+		err = -ENOMEM;
+		goto err_alloc_sgt_cache;
+	}
+
 	err = netdev_init(net_dev);
 	if (err)
 		goto err_netdev_init;
@@ -3914,6 +4032,8 @@ static int dpaa2_eth_probe(struct fsl_mc_device *dpni_dev)
 err_alloc_rings:
 err_csum:
 err_netdev_init:
+	free_percpu(priv->sgt_cache);
+err_alloc_sgt_cache:
 	free_percpu(priv->percpu_extras);
 err_alloc_percpu_extras:
 	free_percpu(priv->percpu_stats);
@@ -3959,6 +4079,7 @@ static int dpaa2_eth_remove(struct fsl_mc_device *ls_dev)
 		fsl_mc_free_irqs(ls_dev);
 
 	free_rings(priv);
+	free_percpu(priv->sgt_cache);
 	free_percpu(priv->percpu_stats);
 	free_percpu(priv->percpu_extras);
 
diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
index 2d7ada0f0dbd..9e4ceb92f240 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
@@ -125,6 +125,7 @@ struct dpaa2_eth_swa {
 	union {
 		struct {
 			struct sk_buff *skb;
+			int sgt_size;
 		} single;
 		struct {
 			struct sk_buff *skb;
@@ -282,7 +283,6 @@ struct dpaa2_eth_drv_stats {
 	__u64	tx_conf_bytes;
 	__u64	tx_sg_frames;
 	__u64	tx_sg_bytes;
-	__u64	tx_reallocs;
 	__u64	rx_sg_frames;
 	__u64	rx_sg_bytes;
 	/* Enqueues retried due to portal busy */
@@ -395,6 +395,12 @@ struct dpaa2_eth_cls_rule {
 	u8 in_use;
 };
 
+#define DPAA2_ETH_SGT_CACHE_SIZE	256
+struct dpaa2_eth_sgt_cache {
+	void *buf[DPAA2_ETH_SGT_CACHE_SIZE];
+	u16 count;
+};
+
 /* Driver private data */
 struct dpaa2_eth_priv {
 	struct net_device *net_dev;
@@ -409,6 +415,7 @@ struct dpaa2_eth_priv {
 
 	u8 num_channels;
 	struct dpaa2_eth_channel *channel[DPAA2_ETH_MAX_DPCONS];
+	struct dpaa2_eth_sgt_cache __percpu *sgt_cache;
 
 	struct dpni_attr dpni_attrs;
 	u16 dpni_ver_major;
diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
index e88269fe3de7..c4cbbcaa9a3f 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
@@ -43,7 +43,6 @@ static char dpaa2_ethtool_extras[][ETH_GSTRING_LEN] = {
 	"[drv] tx conf bytes",
 	"[drv] tx sg frames",
 	"[drv] tx sg bytes",
-	"[drv] tx realloc frames",
 	"[drv] rx sg frames",
 	"[drv] rx sg bytes",
 	"[drv] enqueue portal busy",
-- 
2.25.1