Suspending an open usbnet device results in constant
rescheduling of usbnet_bh.
commit 65841fd5 "usbnet: handle remote wakeup asap"
refactored the usbnet_bh code to allow sharing the
urb allocate and submit code with usbnet_resume. In
this process, a test for, and immediate return on,
ENOLINK from rx_submit was unintentionally dropped.
The rx queue will not grow if rx_submit fails,
making usbnet_bh reschedule itself. This results
in a softirq storm if the error is persistent.
rx_submit translates the usb_submit_urb error
EHOSTUNREACH into ENOLINK, so this is an expected
and persistent error for a suspended device. The
old code tested for this condition and avoided
rescheduling. Putting this test back.
Cc: <sta...@vger.kernel.org> # v3.5
Cc: Ming Lei <ming....@canonical.com>
Cc: Oliver Neukum <oneu...@suse.de>
Signed-off-by: Bjørn Mork <bj...@mork.no>
---
Sorry for not noticing this before, but commit 65841fd5
makes usbnet autosuspend completely unusable. The device
is suspended fine, but burning one CPU core at full load
uses a tiny bit more power making the power saving
negative...
I hope this can go into 3.6 and 3.5-stable ASAP. It is
a hard to notice regression, but all the same a serious
one.
Thanks,
Bjørn
drivers/net/usb/usbnet.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index fd4b26d..fc9f578 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1201,19 +1201,26 @@ deferred:
}
EXPORT_SYMBOL_GPL(usbnet_start_xmit);
-static void rx_alloc_submit(struct usbnet *dev, gfp_t flags)
+static int rx_alloc_submit(struct usbnet *dev, gfp_t flags)
{
struct urb *urb;
int i;
+ int ret = 0;
/* don't refill the queue all at once */
for (i = 0; i < 10 && dev->rxq.qlen < RX_QLEN(dev); i++) {
urb = usb_alloc_urb(0, flags);
if (urb != NULL) {
- if (rx_submit(dev, urb, flags) == -ENOLINK)
- return;
+ ret = rx_submit(dev, urb, flags);
+ if (ret)
+ goto err;
+ } else {
+ ret = -ENOMEM;
+ goto err;
}
}
+err:
+ return ret;
}
/*-------------------------------------------------------------------------*/
@@ -1257,7 +1264,8 @@ static void usbnet_bh (unsigned long param)
int temp = dev->rxq.qlen;
if (temp < RX_QLEN(dev)) {
- rx_alloc_submit(dev, GFP_ATOMIC);
+ if (rx_alloc_submit(dev, GFP_ATOMIC) == -ENOLINK)
+ return;
if (temp != dev->rxq.qlen)
netif_dbg(dev, link, dev->net,
"rxqlen %d --> %d\n",
--
1.7.10.4
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