From 398a708ed5f3ef771d96dfb9b95b5d5170d17eb7 Mon Sep 17 00:00:00 2001 From: Badhri Jagan Sridharan Date: Wed, 24 Sep 2014 18:58:23 -0700 Subject: [PATCH] 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. Change-Id: I316de8e267997137ac189a8b7b2846fa325f4a5a Signed-off-by: Badhri Jagan Sridharan --- drivers/usb/gadget/function/u_ether.c | 119 +++++++++++++++++--------- 1 file changed, 80 insertions(+), 39 deletions(-) diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c index 0d2860a09f40..4119dbb73602 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -53,6 +53,8 @@ * blocks and still have efficient handling. */ #define GETHER_MAX_ETH_FRAME_LEN 15412 +static struct workqueue_struct *uether_wq; + struct eth_dev { /* lock is held while accessing port_usb */ @@ -78,6 +80,7 @@ struct eth_dev { struct sk_buff_head *list); struct work_struct work; + struct work_struct rx_work; unsigned long todo; #define WORK_RX_MEMORY 0 @@ -263,18 +266,16 @@ enomem: 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) { @@ -298,30 +299,8 @@ static void rx_complete(struct usb_ep *ep, struct usb_request *req) } 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 > GETHER_MAX_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 */ @@ -344,22 +323,20 @@ quiesce: /* 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) @@ -424,16 +401,24 @@ static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags) { 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; } @@ -443,6 +428,36 @@ static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags) 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); @@ -786,6 +801,7 @@ struct eth_dev *gether_setup_name(struct usb_gadget *g, 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); @@ -1129,6 +1145,7 @@ void gether_disconnect(struct gether *link) { struct eth_dev *dev = link->ioport; struct usb_request *req; + struct sk_buff *skb; WARN_ON(!dev); if (!dev) @@ -1169,6 +1186,12 @@ void gether_disconnect(struct gether *link) 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->desc = NULL; /* finish forgetting about this USB link episode */ @@ -1182,5 +1205,23 @@ void gether_disconnect(struct gether *link) } EXPORT_SYMBOL_GPL(gether_disconnect); -MODULE_LICENSE("GPL"); +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_AUTHOR("David Brownell"); +MODULE_DESCRIPTION("ethernet over USB driver"); +MODULE_LICENSE("GPL v2"); -- 2.20.1