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Commit f205162c authored by Devdutt Patnaik's avatar Devdutt Patnaik Committed by Azhar Shaikh
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net: usbnet: Add flow control for UL path to IPA 



Implements a queueing mechanism to buffer packets
if IPA does not have free descriptors on UL path.
Packets are only dropped if we run out of free
elements on the queue. This flow control mechanism
is needed to avoid unrecoverable IPA side failures
if we continuously sends packets when IPA is out
of descriptors. Also, do not recycle rx urb in
interrupt context. This is causing memory allocation
failure for high throughput use case.

Crs-Fixed: 867682
Change-Id: I2f4755a039f21e7f533c1a6969a2246b96624011
Signed-off-by: default avatarDevdutt Patnaik <dpatnaik@codeaurora.org>
Signed-off-by: default avatarAzhar Shaikh <azhars@codeaurora.org>
parent f499fca0

drivers/net/usb/usbnet.c

+122 −8
Original line number Diff line number Diff line
@@ -46,7 +46,7 @@ 
#include <linux/kernel.h>

#include <linux/pm_runtime.h>

#include <linux/debugfs.h>



#include <linux/types.h>

#define DRIVER_VERSION		"22-Aug-2005"
@@ -326,14 +326,60 @@ static void __usbnet_status_stop_force(struct usbnet *dev) 
void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb)

{

	int	status;

	struct sk_buff *pend_skb;

	struct usbnet_ipa_ctx	*punet_ipa = dev->pusbnet_ipa;

	struct	ipa_tx_meta ipa_meta = {0x0};

	u32	pkts_to_send, ret, qlen = 0;

	u8	protocol_type = (skb->data[ETH_HLEN] & 0xf0);



	/* Pass IPv4 and IPv6 packets to IPA by peeking into the IP header */

	if (enable_ipa_bridge && (protocol_type == 0x40 ||

	    protocol_type == 0x60)) {

		spin_lock(&dev->ipa_pendq.lock);

		qlen = skb_queue_len(&dev->ipa_pendq);

		/* drop pkts */

		if (!dev->ipa_free_desc_cnt &&

		    qlen > (2 * USBNET_IPA_SYS_PIPE_DNE_PKTS)) {

			pr_debug_ratelimited("drop pkt ipa pending qlen = %d\n",

					     qlen);

			dev_kfree_skb(skb);

			goto unlock_and_schedule;

		}



		__skb_queue_tail(&dev->ipa_pendq, skb);

		if (dev->ipa_free_desc_cnt) {

			/* send fixed number of packets to ODU bridge driver

			 * now. Number should be smaller than total desc count

			 * to keep both usbnet and odu driver busy and prevent

			 * pending packet counts to quickly reach to drop count

			 * limit when descs are available without waiting for

			 * work to get a chance to run.

			 */

			pkts_to_send = dev->ipa_free_desc_cnt;

			pkts_to_send = (pkts_to_send > 50) ? 50 : pkts_to_send;

			while (pkts_to_send &&

			       (pend_skb = __skb_dequeue(&dev->ipa_pendq))) {

				ipa_meta.dma_address_valid = false;

				/* Send Packet to ODU bridge Driver */

				spin_unlock(&dev->ipa_pendq.lock);

				ret = odu_bridge_tx_dp(pend_skb, &ipa_meta);

				spin_lock(&dev->ipa_pendq.lock);

				if (ret) {

					pr_err_ratelimited("%s: ret %d\n",

							   __func__, ret);

					dev_kfree_skb(pend_skb);

					punet_ipa->stats.rx_ipa_send_fail++;

					goto unlock_and_schedule;

				} else {

					dev->pusbnet_ipa->stats.rx_ipa_send++;

		odu_bridge_tx_dp(skb, &ipa_meta);

					dev->ipa_free_desc_cnt--;

				}

				pkts_to_send--;

			}

		}

unlock_and_schedule:

		spin_unlock(&dev->ipa_pendq.lock);

		if (dev->ipa_pendq.qlen)

			queue_work(usbnet_wq, &dev->ipa_send_task);

		return;

	}
@@ -658,7 +704,11 @@ block: 
	state = defer_bh(dev, skb, &dev->rxq, state);



	if (urb) {

		if (netif_running (dev->net) &&

		/* observing memory allocation failure in atomic context for

		 * high throughput use cases of ipa bridge. Avoid recycling

		 * of rx urb for ipa bridge, let usbnet_bh submit the rx urb.

		 */

		if (!enable_ipa_bridge && netif_running(dev->net) &&

		    !test_bit (EVENT_RX_HALT, &dev->flags) &&

		    state != unlink_start) {

			rx_submit (dev, urb, GFP_ATOMIC);
@@ -1511,7 +1561,7 @@ static void usbnet_bh (unsigned long param) 
		int	temp = dev->rxq.qlen;



		if (temp < RX_QLEN(dev)) {

			if (rx_alloc_submit(dev, GFP_ATOMIC) == -ENOLINK)

			if (rx_alloc_submit(dev, GFP_KERNEL) == -ENOLINK)

				return;

			if (temp != dev->rxq.qlen)

				netif_dbg(dev, link, dev->net,
@@ -1566,6 +1616,16 @@ static ssize_t usbnet_ipa_debugfs_read_stats(struct file *file, 
	"IPA TX Send: ", usbnet_ipa->stats.tx_ipa_send);

	len += scnprintf(buf + len, buf_len - len, "%25s %10llu\n",

	"IPA TX Send Err: ", usbnet_ipa->stats.tx_ipa_send_err);

	len += scnprintf(buf + len, buf_len - len, "%25s %10llu\n",

	"IPA RX Packet Drops: ", usbnet_ipa->stats.flow_control_pkt_drop);

	len += scnprintf(buf + len, buf_len - len, "%25s %10llu\n",

	"IPA flow ctrl pkt drop ", usbnet_ipa->stats.flow_control_pkt_drop);

	len += scnprintf(buf + len, buf_len - len, "%25s %10llu\n",

	"IPA low watermark cnt ", usbnet_ipa->stats.ipa_low_watermark_cnt);

	len += scnprintf(buf + len, buf_len - len, "%25s %10d\n",

	"IPA free desc cnt ", dev->ipa_free_desc_cnt);

	len += scnprintf(buf + len, buf_len - len, "%25s %10d\n",

	"IPA send qlen ", dev->ipa_pendq.qlen);



	if (len > buf_len)

		len = buf_len;
@@ -1642,6 +1702,7 @@ void usbnet_disconnect (struct usb_interface *intf) 
	cancel_work_sync(&dev->kevent);



	if (enable_ipa_bridge) {

		skb_queue_purge(&dev->ipa_pendq);

		retval = odu_bridge_disconnect();

		if (retval)

			dev_dbg(&dev->udev->dev,
@@ -1756,6 +1817,7 @@ static void usbnet_ipa_tx_dp_cb(void *priv, enum ipa_dp_evt_type evt, 
	struct usbnet_ipa_ctx *usbnet_ipa = dev->pusbnet_ipa;

	struct sk_buff *skb = (struct sk_buff *)data;

	int status;

	u32 qlen = 0;



	switch (evt) {

	case IPA_RECEIVE:
@@ -1774,6 +1836,15 @@ static void usbnet_ipa_tx_dp_cb(void *priv, enum ipa_dp_evt_type evt, 
		dev->net->stats.rx_packets++;

		dev->net->stats.rx_bytes += skb->len;

		dev_kfree_skb(skb);

		spin_lock(&dev->ipa_pendq.lock);

		qlen = skb_queue_len(&dev->ipa_pendq);

		dev->ipa_free_desc_cnt++;

		if (qlen && dev->ipa_free_desc_cnt < dev->ipa_low_watermark)

				usbnet_ipa->stats.ipa_low_watermark_cnt++;

		spin_unlock(&dev->ipa_pendq.lock);



		if (qlen)

			queue_work(usbnet_wq, &dev->ipa_send_task);

		break;



	default:
@@ -1831,6 +1902,46 @@ static int usbnet_ipa_set_perf_level(struct usbnet *dev) 
	return ret;

}



/* usbnet_ipa_send_routine - Sends packets to IPA/ODU bridge Driver

 * Scheduled on RX of IPA_WRITE_DONE Event

 */

static void usbnet_ipa_send_routine(struct work_struct *work)

{

	struct usbnet *dev = container_of(work,

				struct usbnet, ipa_send_task);

	struct sk_buff *skb;

	struct ipa_tx_meta ipa_meta = {0x0};

	int ret = 0;



	/* Send all pending packets to IPA.

	 * Compute the number of desc left for HW and send packets accordingly

	 */

	spin_lock(&dev->ipa_pendq.lock);

	if (dev->ipa_free_desc_cnt < dev->ipa_low_watermark) {

		dev->pusbnet_ipa->stats.ipa_low_watermark_cnt++;

		spin_unlock(&dev->ipa_pendq.lock);

		return;

	}



	while (dev->ipa_free_desc_cnt &&

	       (skb = __skb_dequeue(&dev->ipa_pendq))) {

		ipa_meta.dma_address_valid = false;

		/* Send Packet to ODU bridge Driver */

		spin_unlock(&dev->ipa_pendq.lock);

		ret = odu_bridge_tx_dp(skb, &ipa_meta);

		spin_lock(&dev->ipa_pendq.lock);

		if (ret) {

			pr_err("%s: ret %d\n", __func__, ret);

			dev_kfree_skb(skb);

			dev->pusbnet_ipa->stats.rx_ipa_send_fail++;

		} else {

			dev->pusbnet_ipa->stats.rx_ipa_send++;

			dev->ipa_free_desc_cnt--;

		}

	}

	spin_unlock(&dev->ipa_pendq.lock);

}



int

usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)

{
@@ -1897,7 +2008,6 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod) 
	mutex_init (&dev->phy_mutex);

	mutex_init(&dev->interrupt_mutex);

	dev->interrupt_count = 0;



	dev->net = net;

	strcpy (net->name, "usb%d");

	memcpy (net->dev_addr, node_id, sizeof node_id);
@@ -2011,6 +2121,10 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod) 
		dev->ipa_high_watermark = USBNET_IPA_SYS_PIPE_MAX_PKTS_DESC;

		dev->ipa_low_watermark = USBNET_IPA_SYS_PIPE_MIN_PKTS_DESC;



		/* Initialize flow control variables */

		skb_queue_head_init(&dev->ipa_pendq);

		INIT_WORK(&dev->ipa_send_task, usbnet_ipa_send_routine);



		status = usbnet_ipa_setup_rm(dev);

		if (status) {

			pr_err("USBNET: IPA Setup RM Failed\n");

include/linux/usb/usbnet.h

+8 −0
Original line number Diff line number Diff line
@@ -38,6 +38,10 @@ struct usbnet_ipa_stats { 
	/* TX Side*/

	uint64_t tx_ipa_send;

	uint64_t tx_ipa_send_err;



	/* Flow Control stats */

	uint64_t flow_control_pkt_drop;

	uint64_t ipa_low_watermark_cnt;

};



struct usbnet_ipa_ctx {
@@ -107,6 +111,10 @@ struct usbnet { 
	u16 ipa_free_desc_cnt;

	u16 ipa_high_watermark;

	u16 ipa_low_watermark;



	struct sk_buff_head	ipa_pendq;

	/* work to send pending packets to ipa */

	struct work_struct ipa_send_task;

};



static inline struct usb_driver *driver_of(struct usb_interface *intf)