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usb gadget: g_ether spinlock recursion fix

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The new spinlock debug code turned up a spinlock recursion bug in the
Ethernet gadget driver on a disconnect path; it would show up with any
UDC driver where the cancellation of active requests was synchronous,
rather than e.g. delayed until a controller's completion IRQ.

That recursion is fixed here by creating and using a new spinlock to
protect the relevant lists.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
David Brownell 2006-08-21 15:26:38 -07:00 committed by Greg Kroah-Hartman
parent ea186651d5
commit 789851cf00
1 changed files with 31 additions and 14 deletions
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45
drivers/usb/gadget/ether.c
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@ -117,6 +117,8 @@ struct eth_dev {
struct usb_ep *in_ep, *out_ep, *status_ep;
const struct usb_endpoint_descriptor
*in, *out, *status;
spinlock_t req_lock;
struct list_head tx_reqs, rx_reqs;
struct net_device *net;
@ -1066,21 +1068,31 @@ static void eth_reset_config (struct eth_dev *dev)
*/
if (dev->in) {
usb_ep_disable (dev->in_ep);
spin_lock(&dev->req_lock);
while (likely (!list_empty (&dev->tx_reqs))) {
req = container_of (dev->tx_reqs.next,
struct usb_request, list);
list_del (&req->list);
spin_unlock(&dev->req_lock);
usb_ep_free_request (dev->in_ep, req);
spin_lock(&dev->req_lock);
}
spin_unlock(&dev->req_lock);
}
if (dev->out) {
usb_ep_disable (dev->out_ep);
spin_lock(&dev->req_lock);
while (likely (!list_empty (&dev->rx_reqs))) {
req = container_of (dev->rx_reqs.next,
struct usb_request, list);
list_del (&req->list);
spin_unlock(&dev->req_lock);
usb_ep_free_request (dev->out_ep, req);
spin_lock(&dev->req_lock);
}
spin_unlock(&dev->req_lock);
}
if (dev->status) {
@ -1659,9 +1671,9 @@ enomem:
if (retval) {
DEBUG (dev, "rx submit --> %d\n", retval);
dev_kfree_skb_any (skb);
spin_lock (&dev->lock);
spin_lock(&dev->req_lock);
list_add (&req->list, &dev->rx_reqs);
spin_unlock (&dev->lock);
spin_unlock(&dev->req_lock);
}
return retval;
}
@ -1730,8 +1742,9 @@ quiesce:
dev_kfree_skb_any (skb);
if (!netif_running (dev->net)) {
clean:
/* nobody reading rx_reqs, so no dev->lock */
spin_lock(&dev->req_lock);
list_add (&req->list, &dev->rx_reqs);
spin_unlock(&dev->req_lock);
req = NULL;
}
if (req)
@ -1782,15 +1795,18 @@ static int alloc_requests (struct eth_dev *dev, unsigned n, gfp_t gfp_flags)
{
int status;
spin_lock(&dev->req_lock);
status = prealloc (&dev->tx_reqs, dev->in_ep, n, gfp_flags);
if (status < 0)
goto fail;
status = prealloc (&dev->rx_reqs, dev->out_ep, n, gfp_flags);
if (status < 0)
goto fail;
return 0;
goto done;
fail:
DEBUG (dev, "can't alloc requests\n");
done:
spin_unlock(&dev->req_lock);
return status;
}
@ -1800,21 +1816,21 @@ static void rx_fill (struct eth_dev *dev, gfp_t gfp_flags)
unsigned long flags;
/* fill unused rxq slots with some skb */
spin_lock_irqsave (&dev->lock, flags);
spin_lock_irqsave(&dev->req_lock, flags);
while (!list_empty (&dev->rx_reqs)) {
req = container_of (dev->rx_reqs.next,
struct usb_request, list);
list_del_init (&req->list);
spin_unlock_irqrestore (&dev->lock, flags);
spin_unlock_irqrestore(&dev->req_lock, flags);
if (rx_submit (dev, req, gfp_flags) < 0) {
defer_kevent (dev, WORK_RX_MEMORY);
return;
}
spin_lock_irqsave (&dev->lock, flags);
spin_lock_irqsave(&dev->req_lock, flags);
}
spin_unlock_irqrestore (&dev->lock, flags);
spin_unlock_irqrestore(&dev->req_lock, flags);
}
static void eth_work (void *_dev)
@ -1848,9 +1864,9 @@ static void tx_complete (struct usb_ep *ep, struct usb_request *req)
}
dev->stats.tx_packets++;
spin_lock (&dev->lock);
spin_lock(&dev->req_lock);
list_add (&req->list, &dev->tx_reqs);
spin_unlock (&dev->lock);
spin_unlock(&dev->req_lock);
dev_kfree_skb_any (skb);
atomic_dec (&dev->tx_qlen);
@ -1896,12 +1912,12 @@ static int eth_start_xmit (struct sk_buff *skb, struct net_device *net)
/* ignores USB_CDC_PACKET_TYPE_DIRECTED */
}
spin_lock_irqsave (&dev->lock, flags);
spin_lock_irqsave(&dev->req_lock, flags);
req = container_of (dev->tx_reqs.next, struct usb_request, list);
list_del (&req->list);
if (list_empty (&dev->tx_reqs))
netif_stop_queue (net);
spin_unlock_irqrestore (&dev->lock, flags);
spin_unlock_irqrestore(&dev->req_lock, flags);
/* no buffer copies needed, unless the network stack did it
* or the hardware can't use skb buffers.
@ -1955,11 +1971,11 @@ static int eth_start_xmit (struct sk_buff *skb, struct net_device *net)
drop:
dev->stats.tx_dropped++;
dev_kfree_skb_any (skb);
spin_lock_irqsave (&dev->lock, flags);
spin_lock_irqsave(&dev->req_lock, flags);
if (list_empty (&dev->tx_reqs))
netif_start_queue (net);
list_add (&req->list, &dev->tx_reqs);
spin_unlock_irqrestore (&dev->lock, flags);
spin_unlock_irqrestore(&dev->req_lock, flags);
}
return 0;
}
@ -2378,6 +2394,7 @@ autoconf_fail:
return status;
dev = netdev_priv(net);
spin_lock_init (&dev->lock);
spin_lock_init (&dev->req_lock);
INIT_WORK (&dev->work, eth_work, dev);
INIT_LIST_HEAD (&dev->tx_reqs);
INIT_LIST_HEAD (&dev->rx_reqs);