The race may happen when a device (e.g. YOTA 4G LTE Modem) is
unplugged while the system is downloading a large file from the Net.

Hardware breakpoints and Kprobes with delays were used to confirm that
the race does actually happen.

The race is on skb_queue ('next' pointer) between usbnet_stop()
and rx_complete(), which, in turn, calls usbnet_bh().

Here is a part of the call stack with the code where the changes to the
queue happen. The line numbers are for the kernel 4.1.0:

*0 __skb_unlink (skbuff.h:1517)
    prev->next = next;
*1 defer_bh (usbnet.c:430)
    spin_lock_irqsave(&list->lock, flags);
    old_state = entry->state;
    entry->state = state;
    __skb_unlink(skb, list);
    spin_unlock(&list->lock);
    spin_lock(&dev->done.lock);
    __skb_queue_tail(&dev->done, skb);
    if (dev->done.qlen == 1)
        tasklet_schedule(&dev->bh);
    spin_unlock_irqrestore(&dev->done.lock, flags);
*2 rx_complete (usbnet.c:640)
    state = defer_bh(dev, skb, &dev->rxq, state);

At the same time, the following code repeatedly checks if the queue is
empty and reads these values concurrently with the above changes:

*0  usbnet_terminate_urbs (usbnet.c:765)
    /* maybe wait for deletions to finish. */
    while (!skb_queue_empty(&dev->rxq)
        && !skb_queue_empty(&dev->txq)
        && !skb_queue_empty(&dev->done)) {
            schedule_timeout(msecs_to_jiffies(UNLINK_TIMEOUT_MS));
            set_current_state(TASK_UNINTERRUPTIBLE);
            netif_dbg(dev, ifdown, dev->net,
                  "waited for %d urb completions\n", temp);
    }
*1  usbnet_stop (usbnet.c:806)
    if (!(info->flags & FLAG_AVOID_UNLINK_URBS))
        usbnet_terminate_urbs(dev);

As a result, it is possible, for example, that the skb is removed from
dev->rxq by __skb_unlink() before the check
"!skb_queue_empty(&dev->rxq)" in usbnet_terminate_urbs() is made. It is
also possible in this case that the skb is added to dev->done queue
after "!skb_queue_empty(&dev->done)" is checked. So
usbnet_terminate_urbs() may stop waiting and return while dev->done
queue still has an item.

Locking in defer_bh() and usbnet_terminate_urbs() was revisited to avoid
this race.
Signed-off-by: NEugene Shatokhin <eugene.shatokhin@rosalab.ru>
Reviewed-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It is needed to check EVENT_NO_RUNTIME_PM bit of dev->flags in
usbnet_stop(), but its value should be read before it is cleared
when dev->flags is set to 0.

The problem was spotted and the fix was provided by
Oliver Neukum <oneukum@suse.de>.
Signed-off-by: NEugene Shatokhin <eugene.shatokhin@rosalab.ru>
Acked-by: NOliver Neukum <oneukum@suse.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

transfer_buffer_length is of type u32. It's therefore wrong to assign it
to a signed integer. This patch avoids the overflow.

It's worth noting that entry->length here is a long; perhaps it would be
beneficial at somepoint to change this to be unsigned as well, if
nothing else relies on its signedness for error conditions or the like.
Signed-off-by: NJason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

"kevent" is an extremely generic name that causes trouble
if debugging for work queues is used. So change it to
something clear.
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

cdc_ncm disagrees with usbnet about how much framing overhead should
be counted in the tx_bytes statistics, and tries 'fix' this by
decrementing tx_bytes on the transmit path.  But statistics must never
be decremented except due to roll-over; this will thoroughly confuse
user-space.  Also, tx_bytes is only incremented by usbnet in the
completion path.

Fix this by requiring drivers that set FLAG_MULTI_FRAME to set a
tx_bytes delta along with the tx_packets count.

Fixes: beeecd42 ("net: cdc_ncm/cdc_mbim: adding NCM protocol statistics")
Signed-off-by: NBen Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: NBjørn Mork <bjorn@mork.no>

Currently the usbnet core does not update the tx_packets statistic for
drivers with FLAG_MULTI_PACKET and there is no hook in the TX
completion path where they could do this.

cdc_ncm and dependent drivers are bumping tx_packets stat on the
transmit path while asix and sr9800 aren't updating it at all.

Add a packet count in struct skb_data so these drivers can fill it
in, initialise it to 1 for other drivers, and add the packet count
to the tx_packets statistic on completion.
Signed-off-by: NBen Hutchings <ben.hutchings@codethink.co.uk>
Tested-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently the usbnet core does not update the tx_packets statistic for
drivers with FLAG_MULTI_PACKET and there is no hook in the TX
completion path where they could do this.

cdc_ncm and dependent drivers are bumping tx_packets stat on the
transmit path while asix and sr9800 aren't updating it at all.

Add a packet count in struct skb_data so these drivers can fill it
in, initialise it to 1 for other drivers, and add the packet count
to the tx_packets statistic on completion.
Signed-off-by: NBen Hutchings <ben.hutchings@codethink.co.uk>
Tested-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Call hex2bin() library function, instead of doing conversion here.
Signed-off-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

To delegate promiscuous mode and multicast filtering to the subdriver.
Signed-off-by: NOlivier Blin <olivier.blin@softathome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

USB hub has started to use a workqueue instead of kthread. Let's update
the documentation and comments here and there.

This patch mostly just replaces "khubd" with "hub_wq". There are only few
exceptions where the whole sentence was updated. These more complicated
changes can be found in the following files:

	   Documentation/usb/hotplug.txt
	   drivers/net/usb/usbnet.c
	   drivers/usb/core/hcd.c
	   drivers/usb/host/ohci-hcd.c
	   drivers/usb/host/xhci.c
Signed-off-by: NPetr Mladek <pmladek@suse.cz>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This device needs to be reset to recover from a timeout.
Unfortunately this can be handled only at the level of
the subdrivers.
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This reverts commit 20fbe3ae.

As reported by Stephen Rothwell, it causes compile failures in certain
configurations:

  drivers/net/usb/cdc_subset.c:360:15: error: 'dummy_prereset' undeclared here (not in a function)
    .pre_reset = dummy_prereset,
                 ^
  drivers/net/usb/cdc_subset.c:361:16: error: 'dummy_postreset' undeclared here (not in a function)
    .post_reset = dummy_postreset,
                  ^
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NDavid Miller <davem@davemloft.net>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This device needs to be reset to recover from a timeout.
Unfortunately this can be handled only at the level of
the subdrivers.
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This fixes a race which happens by freeing an object on the stack.
Quoting Julius:
> The issue is
> that it calls usbnet_terminate_urbs() before that, which temporarily
> installs a waitqueue in dev->wait in order to be able to wait on the
> tasklet to run and finish up some queues. The waiting itself looks
> okay, but the access to 'dev->wait' is totally unprotected and can
> race arbitrarily. I think in this case usbnet_bh() managed to succeed
> it's dev->wait check just before usbnet_terminate_urbs() sets it back
> to NULL. The latter then finishes and the waitqueue_t structure on its
> stack gets overwritten by other functions halfway through the
> wake_up() call in usbnet_bh().

The fix is to just not allocate the data structure on the stack.
As dev->wait is abused as a flag it also takes a runtime PM change
to fix this bug.
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Reported-by: NGrant Grundler <grundler@google.com>
Tested-by: NGrant Grundler <grundler@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch removes a generic hard_header_len check from the usbnet
module that is causing dropped packages under certain circumstances
for devices that send rx packets that cross urb boundaries.

One example is the AX88772B which occasionally send rx packets that
cross urb boundaries where the remaining partial packet is sent with
no hardware header. When the buffer with a partial packet is of less
number of octets than the value of hard_header_len the buffer is
discarded by the usbnet module.

With AX88772B this can be reproduced by using ping with a packet
size between 1965-1976.

The bug has been reported here:

https://bugzilla.kernel.org/show_bug.cgi?id=29082

This patch introduces the following changes:
- Removes the generic hard_header_len check in the rx_complete
  function in the usbnet module.
- Introduces a ETH_HLEN check for skbs that are not cloned from
  within a rx_fixup callback.
- For safety a hard_header_len check is added to each rx_fixup
  callback function that could be affected by this change.
  These extra checks could possibly be removed by someone
  who has the hardware to test.
- Removes a call to dev_kfree_skb_any() and instead utilizes the
  dev->done list to queue skbs for cleanup.

The changes place full responsibility on the rx_fixup callback
functions that clone skbs to only pass valid skbs to the
usbnet_skb_return function.
Signed-off-by: NEmil Goode <emilgoode@gmail.com>
Reported-by: NIgor Gnatenko <i.gnatenko.brain@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 60e453a9 ("USBNET: fix handling padding packet")
added an extra SG entry in case padding is necessary, but
failed to update the initialisation of the list. This can
cause list traversal to fall off the end of the list,
resulting in an oops.

Fixes: 60e453a9 ("USBNET: fix handling padding packet")
Reported-by: NThomas Kear <thomas@kear.co.nz>
Cc: Ming Lei <ming.lei@canonical.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Tested-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Several files refer to an old address for the Free Software Foundation
in the file header comment.  Resolve by replacing the address with
the URL <http://www.gnu.org/licenses/> so that we do not have to keep
updating the header comments anytime the address changes.

CC: Oliver Neukum <oliver@neukum.org>
CC: Steve Glendinning <steve.glendinning@shawell.net>
CC: Oliver Neukum <oneukum@suse.de>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since commit 7b0c5f21
"sierra_net: keep status interrupt URB active", sierra_net triggers
status interrupt polling before the net_device is opened (in order to
properly receive the sync message response).

To be able to receive further interrupts, the interrupt urb needs to be
re-submitted, so this patch removes the bogus check for netif_running().
Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Tested-by: NDan Williams <dcbw@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix to return -ENOMEM in the padding pkt alloc fail error handling
case instead of 0, as done elsewhere in this function.
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 638c5115(USBNET: support DMA SG) introduces DMA SG
if the usb host controller is capable of building packet from
discontinuous buffers, but missed handling padding packet when
building DMA SG.

This patch attachs the pre-allocated padding packet at the
end of the sg list, so padding packet can be sent to device
if drivers require that.
Reported-by: NDavid Laight <David.Laight@aculab.com>
Acked-by: NOliver Neukum <oliver@neukum.org>
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This module generates a common default address on init,
using eth_random_addr. Set addr_assign_type to let
userspace know the address is random unless it was
overridden by the minidriver.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oliver@neukum.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch introduces support of DMA SG if the USB host controller
which usbnet device is attached to is capable of building packet from
discontinuous buffers.

The patch supports passing the skb fragment buffers to usb stack directly
via urb->sg.

Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Grant Grundler <grundler@google.com>
Cc: Freddy Xin <freddy@asix.com.tw>
Cc: Alan Stern <stern@rowland.harvard.edu>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The default RX_QLEN()/TX_QLEN() didn't consider super speed
USB device, so only max 4 URBs are scheduled at the same time
for tx/rx, then USB3 NIC can't perform very well.

With this patch, both rx and tx thoughput are increased more than
100Mbps when doing iperf test on ax88179_178a USB 3.0 NIC.
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch centralizes computing of max rx/tx qlen, because:

- RX_QLEN()/TX_QLEN() is called in hot path
- computing depends on device's usb speed, now we have ls/fs, hs, ss,
so more checks need to be involved
- in fact, max rx/tx qlen should not only depend on device USB
speed, but also depend on ethernet link speed, so we need to
consider that in future.
- if SG support is done, max tx qlen may need change too

Generally, hard_mtu and rx_urb_size are changed in bind(), reset()
and link_reset() callback, and change mtu network operation, this
patches introduces the API of usbnet_update_max_qlen(), and calls
it in above path.
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 84ebc102 (USB: remove
CONFIG_USB_SUSPEND option) failed to remove all of the usages of
USB_SUSPEND throughout the kernel.  This patch (as1677) removes the
remaining instances of that symbol.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Some drivers (sierra_net) need the status interrupt URB
active even when the device is closed, because they receive
custom indications from firmware.  Add functions to refcount
the status interrupt URB submit/kill operation so that
sub-drivers and the generic driver don't fight over whether
the status interrupt URB is active or not.

A sub-driver can call usbnet_status_start() at any time, but
the URB is only submitted the first time the function is
called.  Likewise, when the sub-driver is done with the URB,
it calls usbnet_status_stop() but the URB is only killed when
all users have stopped it.  The URB is still killed and
re-submitted for suspend/resume, as before, with the same
refcount it had at suspend.
Signed-off-by: NDan Williams <dcbw@redhat.com>
Acked-by: NOliver Neukum <oliver@neukum.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The link change is detected via the interrupt pipe, and bulk
pipes are responsible for transfering packets, so it is reasonable
to stop bulk transfer after link is reported as off.

Two adavantages may be obtained with stopping bulk transfer
after link becomes off:

- USB bus bandwidth is saved(USB bus is shared bus except for
USB3.0), for example, lots of 'IN' token packets and 'NYET'
handshake packets is transfered on 2.0 bus.

- probabaly power might be saved for usb host controller since
cancelling bulk transfer may disable the asynchronous schedule of
host controller.

With this patch, when link becomes off, about ~10% performance
boost can be found on bulk transfer of anther usb device which
is attached to same bus with the usbnet device, see below
test on next-20130410:

- read from usb mass storage(Sandisk Extreme USB 3.0) on pandaboard
with below command after unplugging ethernet cable:

	dd if=/dev/sda iflag=direct of=/dev/null bs=1M count=800

- without the patch
1, 838860800 bytes (839 MB) copied, 36.2216 s, 23.2 MB/s
2, 838860800 bytes (839 MB) copied, 35.8368 s, 23.4 MB/s
3, 838860800 bytes (839 MB) copied, 35.823 s, 23.4 MB/s
4, 838860800 bytes (839 MB) copied, 35.937 s, 23.3 MB/s
5, 838860800 bytes (839 MB) copied, 35.7365 s, 23.5 MB/s
average: 23.6MB/s

- with the patch
1, 838860800 bytes (839 MB) copied, 32.3817 s, 25.9 MB/s
2, 838860800 bytes (839 MB) copied, 31.7389 s, 26.4 MB/s
3, 838860800 bytes (839 MB) copied, 32.438 s, 25.9 MB/s
4, 838860800 bytes (839 MB) copied, 32.5492 s, 25.8 MB/s
5, 838860800 bytes (839 MB) copied, 31.6178 s, 26.5 MB/s
average: 26.1MB/s
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use usbnet_link_change to handle link change centrally.
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch introduces the API of usbnet_link_change, so that
usbnet can handle link change centrally, which may help to
implement killing traffic URBs for saving USB bus bandwidth
and host controller power.
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

alloc failures already get standardized OOM
messages and a dump_stack.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It is normal for minidrivers accumulating frames to return NULL
from their tx_fixup function. We do not want to count this as a
drop, or log any debug messages.  A different exit path is
therefore chosen for such drivers, skipping the debug message
and the tx_dropped increment.

The test for accumulating drivers was however completely bogus,
making the exit path selection depend on whether the user had
enabled tx_err logging or not. This would arbitrarily mess up
accounting for both accumulating and non-accumulating minidrivers,
and would result in unwanted debug messages for the accumulating
drivers.

Fix by testing for FLAG_MULTI_PACKET instead, which probably was
the intention from the beginning.  This usage match the documented
behaviour of this flag:

 Indicates to usbnet, that USB driver accumulates multiple IP packets.
 Affects statistic (counters) and short packet handling.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A device sending 0 length frames as fast as it can has been
observed killing the host system due to the resulting memory
pressure.

Temporarily disable RX skb allocation and URB submission when
the current error ratio is high, preventing us from trying to
allocate an infinite number of skbs.  Reenable as soon as we
are finished processing the done queue, allowing the device
to continue working after short error bursts.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We do have some USB net devices, which cannot do ARP.
so we can introduce a new flag FLAG_NOARP, then client drivers
can easily handle this kind of devices
Signed-off-by: NWei Shuai <cpuwolf@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Centralise common code for manage_power() in usbnet
by making a generic simple implementation
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If a device fails to do remote wakeup, this is no reason
to abort an open totally. This patch just continues without
runtime PM.
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

when something goes wrong, a flood of these messages can be
generated by usbnet (thousands per second).  This doesn't
generally *help* the condition so this patch ratelimits the
rate of their generation.

There's an underlying problem in usbnet's kevent deferral
mechanism which needs fixing, specifically that events *can*
get dropped and not handled.  This patch doesn't address this,
but just mitigates fallout caused by the current implemention.
Signed-off-by: NSteve Glendinning <steve.glendinning@shawell.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch gets the runtime PM reference count before calling
usbnet_{read|write}_cmd, and puts it after completion of the
usbnet_{read|write}_cmd, so that the usb control message can always
be sent to one active device in the non-PM context.
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch introduces the below two helpers to prepare for solving
the usbnet runtime PM problem, which may cause some network utilities
(ifconfig, ethtool,...) touch a suspended device.

	usbnet_read_cmd_nopm()
	usbnet_write_cmd_nopm()

The above two helpers should be called by usbnet resume/suspend
callback to avoid deadlock.
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Driver anchors the tx urbs and defers the urb submission if
a transmit request comes when the interface is suspended.
Anchoring urb increments the urb reference count. These
deferred urbs are later accessed by calling usb_get_from_anchor()
for submission during interface resume. usb_get_from_anchor()
unanchors the urb but urb reference count remains same.
This causes the urb reference count to remain non-zero
after usb_free_urb() gets called and urb never gets freed.
Hence call usb_put_urb() after anchoring the urb to properly
balance the reference count for these deferred urbs. Also,
unanchor these deferred urbs during disconnect, to free them
up.
Signed-off-by: NHemant Kumar <hemantk@codeaurora.org>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch introduces the below 3 usb command helpers:

	usbnet_read_cmd / usbnet_write_cmd / usbnet_write_cmd_async

so that each low level driver doesn't need to implement them
by itself, and the dma buffer allocation for usb transfer and
runtime PM things can be handled just in one place.
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>