usb: u_ether: Add workqueue as bottom half handler for rx data path
u_ether driver passes rx data to network layer and resubmits the
request back to usb hardware in interrupt context. Network layer
processes rx data by scheduling tasklet. For high throughput
scenarios on rx data path driver is spending lot of time in interrupt
context due to rx data processing by tasklet and continuous completion
and re-submission of the usb requests which results in watchdog bark.
Hence move the rx data processing and usb request submission to a
workqueue bottom half handler.
CRs-Fixed: 382768
Change-Id: I4788b3d67f7aeeb005655c16b313653e939da79c
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
diff --git a/drivers/usb/gadget/u_ether.c b/drivers/usb/gadget/u_ether.c
index 78ab8b7..fd10394 100644
--- a/drivers/usb/gadget/u_ether.c
+++ b/drivers/usb/gadget/u_ether.c
@@ -46,6 +46,8 @@
#define UETH__VERSION "29-May-2008"
+static struct workqueue_struct *uether_wq;
+
struct eth_dev {
/* lock is held while accessing port_usb
* or updating its backlink port_usb->ioport
@@ -74,6 +76,7 @@
struct sk_buff_head *list);
struct work_struct work;
+ struct work_struct rx_work;
unsigned long todo;
#define WORK_RX_MEMORY 0
@@ -88,7 +91,6 @@
#define DEFAULT_QLEN 2 /* double buffering by default */
-
#ifdef CONFIG_USB_GADGET_DUALSPEED
static unsigned qmult = 10;
@@ -265,18 +267,16 @@
DBG(dev, "rx submit --> %d\n", retval);
if (skb)
dev_kfree_skb_any(skb);
- spin_lock_irqsave(&dev->req_lock, flags);
- list_add(&req->list, &dev->rx_reqs);
- spin_unlock_irqrestore(&dev->req_lock, flags);
}
return retval;
}
static void rx_complete(struct usb_ep *ep, struct usb_request *req)
{
- struct sk_buff *skb = req->context, *skb2;
+ struct sk_buff *skb = req->context;
struct eth_dev *dev = ep->driver_data;
int status = req->status;
+ bool queue = 0;
switch (status) {
@@ -300,30 +300,9 @@
} else {
skb_queue_tail(&dev->rx_frames, skb);
}
- skb = NULL;
- skb2 = skb_dequeue(&dev->rx_frames);
- while (skb2) {
- if (status < 0
- || ETH_HLEN > skb2->len
- || skb2->len > ETH_FRAME_LEN) {
- dev->net->stats.rx_errors++;
- dev->net->stats.rx_length_errors++;
- DBG(dev, "rx length %d\n", skb2->len);
- dev_kfree_skb_any(skb2);
- goto next_frame;
- }
- skb2->protocol = eth_type_trans(skb2, dev->net);
- dev->net->stats.rx_packets++;
- dev->net->stats.rx_bytes += skb2->len;
-
- /* no buffer copies needed, unless hardware can't
- * use skb buffers.
- */
- status = netif_rx(skb2);
-next_frame:
- skb2 = skb_dequeue(&dev->rx_frames);
- }
+ if (!status)
+ queue = 1;
break;
/* software-driven interface shutdown */
@@ -346,22 +325,20 @@
/* FALLTHROUGH */
default:
+ queue = 1;
+ dev_kfree_skb_any(skb);
dev->net->stats.rx_errors++;
DBG(dev, "rx status %d\n", status);
break;
}
- if (skb)
- dev_kfree_skb_any(skb);
- if (!netif_running(dev->net)) {
clean:
- spin_lock(&dev->req_lock);
- list_add(&req->list, &dev->rx_reqs);
- spin_unlock(&dev->req_lock);
- req = NULL;
- }
- if (req)
- rx_submit(dev, req, GFP_ATOMIC);
+ spin_lock(&dev->req_lock);
+ list_add(&req->list, &dev->rx_reqs);
+ spin_unlock(&dev->req_lock);
+
+ if (queue)
+ queue_work(uether_wq, &dev->rx_work);
}
static int prealloc(struct list_head *list, struct usb_ep *ep, unsigned n)
@@ -426,16 +403,24 @@
{
struct usb_request *req;
unsigned long flags;
+ int req_cnt = 0;
/* fill unused rxq slots with some skb */
spin_lock_irqsave(&dev->req_lock, flags);
while (!list_empty(&dev->rx_reqs)) {
+ /* break the nexus of continuous completion and re-submission*/
+ if (++req_cnt > qlen(dev->gadget))
+ break;
+
req = container_of(dev->rx_reqs.next,
struct usb_request, list);
list_del_init(&req->list);
spin_unlock_irqrestore(&dev->req_lock, flags);
if (rx_submit(dev, req, gfp_flags) < 0) {
+ spin_lock_irqsave(&dev->req_lock, flags);
+ list_add(&req->list, &dev->rx_reqs);
+ spin_unlock_irqrestore(&dev->req_lock, flags);
defer_kevent(dev, WORK_RX_MEMORY);
return;
}
@@ -445,6 +430,36 @@
spin_unlock_irqrestore(&dev->req_lock, flags);
}
+static void process_rx_w(struct work_struct *work)
+{
+ struct eth_dev *dev = container_of(work, struct eth_dev, rx_work);
+ struct sk_buff *skb;
+ int status = 0;
+
+ if (!dev->port_usb)
+ return;
+
+ while ((skb = skb_dequeue(&dev->rx_frames))) {
+ if (status < 0
+ || ETH_HLEN > skb->len
+ || skb->len > ETH_FRAME_LEN) {
+ dev->net->stats.rx_errors++;
+ dev->net->stats.rx_length_errors++;
+ DBG(dev, "rx length %d\n", skb->len);
+ dev_kfree_skb_any(skb);
+ continue;
+ }
+ skb->protocol = eth_type_trans(skb, dev->net);
+ dev->net->stats.rx_packets++;
+ dev->net->stats.rx_bytes += skb->len;
+
+ status = netif_rx_ni(skb);
+ }
+
+ if (netif_running(dev->net))
+ rx_fill(dev, GFP_KERNEL);
+}
+
static void eth_work(struct work_struct *work)
{
struct eth_dev *dev = container_of(work, struct eth_dev, work);
@@ -931,6 +946,7 @@
spin_lock_init(&dev->lock);
spin_lock_init(&dev->req_lock);
INIT_WORK(&dev->work, eth_work);
+ INIT_WORK(&dev->rx_work, process_rx_w);
INIT_LIST_HEAD(&dev->tx_reqs);
INIT_LIST_HEAD(&dev->rx_reqs);
@@ -1096,6 +1112,7 @@
{
struct eth_dev *dev = link->ioport;
struct usb_request *req;
+ struct sk_buff *skb;
if (!dev)
return;
@@ -1138,6 +1155,12 @@
spin_lock(&dev->req_lock);
}
spin_unlock(&dev->req_lock);
+
+ spin_lock(&dev->rx_frames.lock);
+ while ((skb = __skb_dequeue(&dev->rx_frames)))
+ dev_kfree_skb_any(skb);
+ spin_unlock(&dev->rx_frames.lock);
+
link->out_ep->driver_data = NULL;
link->out_ep->desc = NULL;
@@ -1151,3 +1174,23 @@
link->ioport = NULL;
spin_unlock(&dev->lock);
}
+
+static int __init gether_init(void)
+{
+ uether_wq = create_singlethread_workqueue("uether");
+ if (!uether_wq) {
+ pr_err("%s: Unable to create workqueue: uether\n", __func__);
+ return -ENOMEM;
+ }
+ return 0;
+}
+module_init(gether_init);
+
+static void __exit gether_exit(void)
+{
+ destroy_workqueue(uether_wq);
+
+}
+module_exit(gether_exit);
+MODULE_DESCRIPTION("ethernet over USB driver");
+MODULE_LICENSE("GPL v2");