Revert "usb: gadget: u_ether: move hardware transmit to RX NAPI"

This reverts commit 716fb91dfe1777bd6d5e598f3d3572214b3ed296.

That commit caused a regression which would end up in a kernel
BUG() as below:

[  101.554300] g_ether gadget: full-speed config #1: CDC Subset/SAFE
[  101.585186] ------------[ cut here ]------------
[  101.600587] kernel BUG at include/linux/netdevice.h:495!
[  101.615850] Internal error: Oops - BUG: 0 [#1] PREEMPT ARM
[  101.645539] Modules linked in:
[  101.660483] CPU: 0 PID: 0 Comm: swapper Not tainted 3.15.0-rc1+ #104
[  101.690175] task: c05dc5c8 ti: c05d2000 task.ti: c05d2000
[  101.705579] PC is at eth_start+0x64/0x8c
[  101.720981] LR is at __netif_schedule+0x7c/0x90
[  101.736455] pc : [<c0299174>]    lr : [<c036a134>]    psr: 60000093
[  101.736455] sp : c05d3d18  ip : c05d3cf8  fp : c05d3d2c
[  101.782340] r10: 00000000  r9 : c196c1f0  r8 : c196c1a0
[  101.797823] r7 : 00000000  r6 : 00000002  r5 : c1976400  r4 : c1976400
[  101.828058] r3 : 00000000  r2 : c05d3ce8  r1 : 00000001  r0 : 00000002
[  101.858722] Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM Segment kernel

Reported-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-of-by: Felipe Balbi <balbi@ti.com>

diff --git a/drivers/usb/gadget/u_ether.c b/drivers/usb/gadget/u_ether.c
index 50d09c289137024271a480acab22ff1d8443d96e..b7d4f82872b700e14d4fc2469bcc1f936a94bf61 100644 (file)
--- a/drivers/usb/gadget/u_ether.c
+++ b/drivers/usb/gadget/u_ether.c
@@ -48,8 +48,6 @@
 
 #define UETH__VERSION  "29-May-2008"
 
-#define GETHER_NAPI_WEIGHT     32
-
 struct eth_dev {
        /* lock is held while accessing port_usb
         */
@@ -74,7 +72,6 @@ struct eth_dev {
                                                struct sk_buff_head *list);
 
        struct work_struct      work;
-       struct napi_struct      rx_napi;
 
        unsigned long           todo;
 #define        WORK_RX_MEMORY          0
@@ -256,16 +253,18 @@ 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;
+       struct sk_buff  *skb = req->context, *skb2;
        struct eth_dev  *dev = ep->driver_data;
        int             status = req->status;
-       bool            rx_queue = 0;
 
        switch (status) {
 
@@ -289,8 +288,30 @@ static void rx_complete(struct usb_ep *ep, struct usb_request *req)
                } else {
                        skb_queue_tail(&dev->rx_frames, skb);
                }
-               if (!status)
-                       rx_queue = 1;
+               skb = NULL;
+
+               skb2 = skb_dequeue(&dev->rx_frames);
+               while (skb2) {
+                       if (status < 0
+                                       || ETH_HLEN > skb2->len
+                                       || skb2->len > VLAN_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);
+               }
                break;
 
        /* software-driven interface shutdown */
@@ -313,20 +334,22 @@ quiesce:
                /* FALLTHROUGH */
 
        default:
-               rx_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);
-
-       if (rx_queue && likely(napi_schedule_prep(&dev->rx_napi)))
-               __napi_schedule(&dev->rx_napi);
+               req = NULL;
+       }
+       if (req)
+               rx_submit(dev, req, GFP_ATOMIC);
 }
 
 static int prealloc(struct list_head *list, struct usb_ep *ep, unsigned n)
@@ -391,24 +414,16 @@ static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags)
 {
        struct usb_request      *req;
        unsigned long           flags;
-       int                     rx_counts = 0;
 
        /* fill unused rxq slots with some skb */
        spin_lock_irqsave(&dev->req_lock, flags);
        while (!list_empty(&dev->rx_reqs)) {
-
-               if (++rx_counts > qlen(dev->gadget, dev->qmult))
-                       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;
                }
@@ -418,41 +433,6 @@ static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags)
        spin_unlock_irqrestore(&dev->req_lock, flags);
 }
 
-static int gether_poll(struct napi_struct *napi, int budget)
-{
-       struct eth_dev  *dev = container_of(napi, struct eth_dev, rx_napi);
-       struct sk_buff  *skb;
-       unsigned int    work_done = 0;
-       int             status = 0;
-
-       while ((skb = skb_dequeue(&dev->rx_frames))) {
-               if (status < 0
-                               || ETH_HLEN > skb->len
-                               || skb->len > VLAN_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);
-               work_done++;
-       }
-
-       if (work_done < budget)
-               napi_complete(&dev->rx_napi);
-
-       return work_done;
-}
-
 static void eth_work(struct work_struct *work)
 {
        struct eth_dev  *dev = container_of(work, struct eth_dev, work);
@@ -645,7 +625,6 @@ static void eth_start(struct eth_dev *dev, gfp_t gfp_flags)
        /* and open the tx floodgates */
        atomic_set(&dev->tx_qlen, 0);
        netif_wake_queue(dev->net);
-       napi_enable(&dev->rx_napi);
 }
 
 static int eth_open(struct net_device *net)
@@ -672,7 +651,6 @@ static int eth_stop(struct net_device *net)
        unsigned long   flags;
 
        VDBG(dev, "%s\n", __func__);
-       napi_disable(&dev->rx_napi);
        netif_stop_queue(net);
 
        DBG(dev, "stop stats: rx/tx %ld/%ld, errs %ld/%ld\n",
@@ -790,7 +768,6 @@ struct eth_dev *gether_setup_name(struct usb_gadget *g,
                return ERR_PTR(-ENOMEM);
 
        dev = netdev_priv(net);
-       netif_napi_add(net, &dev->rx_napi, gether_poll, GETHER_NAPI_WEIGHT);
        spin_lock_init(&dev->lock);
        spin_lock_init(&dev->req_lock);
        INIT_WORK(&dev->work, eth_work);
@@ -853,7 +830,6 @@ struct net_device *gether_setup_name_default(const char *netname)
                return ERR_PTR(-ENOMEM);
 
        dev = netdev_priv(net);
-       netif_napi_add(net, &dev->rx_napi, gether_poll, GETHER_NAPI_WEIGHT);
        spin_lock_init(&dev->lock);
        spin_lock_init(&dev->req_lock);
        INIT_WORK(&dev->work, eth_work);
@@ -1137,7 +1113,6 @@ 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)
@@ -1164,12 +1139,6 @@ 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->in_ep->driver_data = NULL;
        link->in_ep->desc = NULL;