Oliver Neukum <oneukum@xxxxxxx> writes:
> On Thursday 24 January 2013 12:22:54 Bjørn Mork wrote:
>
>> Sorry for being daft, but how do I code the "20 among the last 30" part
>> there?
>
> Just by agreeing that you can live with false negatives but not false positives
>
> if (++counter > 30) {
> counter = bogus = 0;
> } else {
> if (is_bogus(packet)
> bogus++;
> if (bogus > counter/2)
> throttle();
> }
So, add two new counters to struct usbnet for this? That seems a little
overkill to me, but I don't see how else to implement anything like that.
It is still not completely clear to me how the throttling/unthrottling
should be done. It tested with static counters (to avoid having to
rebuild everything for this test) and a new EVENT_RX_THROTTLE flag.
Still on top of my previous patch just for safety while testing, as I am
fed up of having to reboot all the time :-)
Doing the flag test in rx_submit seems simpler than trying to track all
the places this is called. Still checking the dev->done.qlen to be able
to unthrottle.
Was this along the lines you thought?
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 85c7ffd..e3a1d63 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -380,6 +382,13 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
unsigned long lockflags;
size_t size = dev->rx_urb_size;
+
+ if (test_bit(EVENT_RX_THROTTLE, &dev->flags) && dev->done.qlen > 0) {
+ netif_dbg(dev, rx_err, dev->net, "%s: EVENT_RX_THROTTLE: (done.qlen=%u)\n", __func__, dev->done.qlen);
+ usb_free_urb(urb);
+ return -ENOLINK;
+ }
+
/* Do not let a device flood us to death! */
if (dev->done.qlen > 1024) {
netif_dbg(dev, rx_err, dev->net, "done queue filling up (%u) - throttling\n", dev->done.qlen);
@@ -482,6 +491,7 @@ static void rx_complete (struct urb *urb)
struct usbnet *dev = entry->dev;
int urb_status = urb->status;
enum skb_state state;
+ static int counter, bogus;
skb_put (skb, urb->actual_length);
state = rx_done;
@@ -547,6 +557,17 @@ block:
break;
}
+ /* keep track of bogus packet ratio */
+ if (++counter > 30) {
+ counter = bogus = 0;
+ clear_bit(EVENT_RX_THROTTLE, &dev->flags);
+ } else {
+ if (state == rx_cleanup)
+ bogus++;
+ if (bogus > counter/2)
+ set_bit(EVENT_RX_THROTTLE, &dev->flags);
+ }
+
state = defer_bh(dev, skb, &dev->rxq, state);
if (urb) {
--
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