linux-toradex.git/net/core/netpoll.c, branch v4.6-rc5

Revert "netpoll: Fix extra refcount release in netpoll_cleanup()"

2016-04-05T23:34:44+00:00

This reverts commit 543e3a8da5a4c453e992d5351ef405d5e32f27d7.

Direct callers of __netpoll_setup() depend on it to set np->dev,
so we can't simply move that assignment up to netpoll_stup().

Reported-by: Bart Van Assche 
Signed-off-by: Bjorn Helgaas 
Signed-off-by: David S. Miller

netpoll: Fix extra refcount release in netpoll_cleanup()

2016-03-25T15:23:14+00:00

netpoll_setup() does a dev_hold() on np->dev, the netpoll device.  If it
fails, it correctly does a dev_put() but leaves np->dev set.  If we call
netpoll_cleanup() after the failure, np->dev is still set so we do another
dev_put(), which decrements the refcount an extra time.

It's questionable to call netpoll_cleanup() after netpoll_setup() fails,
but it can be difficult to find the problem, and we can easily avoid it in
this case.  The extra decrements can lead to hangs like this:

  unregister_netdevice: waiting for bond0 to become free. Usage count = -3

Set and clear np->dev at the points where we dev_hold() and dev_put() the
device.

Signed-off-by: Bjorn Helgaas 
Signed-off-by: David S. Miller

netpoll: Drop budget parameter from NAPI polling call hierarchy

2015-09-29T21:57:16+00:00

For some reason we were carrying the budget value around between the
various calls to napi->poll.  If for example one of the drivers called had
a bug in which it returned a non-zero value for work this could result in
the budget value becoming negative.

Rather than carry around a value of budget that is 0 or less we can instead
just loop through and pass 0 to each napi->poll call.  If any driver
returns a value for work done that is non-zero then we can report that
driver and continue rather than allowing a bad actor to make the budget
value negative and pass that negative value to napi->poll.

Note, the only actual change here is that instead of letting budget become
negative we are keeping it at 0 regardless of the value returned for work
since it should not be possible for the polling routine to do any actual
work with a budget of 0.  So if the polling routine returns a non-0 value
we are just reporting it and continuing with a budget of 0 rather than
letting that work value be subtracted from the budget of 0.

Signed-off-by: Alexander Duyck 
Signed-off-by: David S. Miller

netpoll: Close race condition between poll_one_napi and napi_disable

2015-09-23T21:32:50+00:00

Drivers might call napi_disable while not holding the napi instance poll_lock.
In those instances, its possible for a race condition to exist between
poll_one_napi and napi_disable.  That is to say, poll_one_napi only tests the
NAPI_STATE_SCHED bit to see if there is work to do during a poll, and as such
the following may happen:

CPU0				CPU1
ndo_tx_timeout			napi_poll_dev
 napi_disable			 poll_one_napi
  test_and_set_bit (ret 0)
				  test_bit (ret 1)
   reset adapter		   napi_poll_routine

If the adapter gets a tx timeout without a napi instance scheduled, its possible
for the adapter to think it has exclusive access to the hardware  (as the napi
instance is now scheduled via the napi_disable call), while the netpoll code
thinks there is simply work to do.  The result is parallel hardware access
leading to corrupt data structures in the driver, and a crash.

Additionaly, there is another, more critical race between netpoll and
napi_disable.  The disabled napi state is actually identical to the scheduled
state for a given napi instance.  The implication being that, if a napi instance
is disabled, a netconsole instance would see the napi state of the device as
having been scheduled, and poll it, likely while the driver was dong something
requiring exclusive access.  In the case above, its fairly clear that not having
the rings in a state ready to be polled will cause any number of crashes.

The fix should be pretty easy.  netpoll uses its own bit to indicate that that
the napi instance is in a state of being serviced by netpoll (NAPI_STATE_NPSVC).
We can just gate disabling on that bit as well as the sched bit.  That should
prevent netpoll from conducting a napi poll if we convert its set bit to a
test_and_set_bit operation to provide mutual exclusion

Change notes:
V2)
	Remove a trailing whtiespace
	Resubmit with proper subject prefix

V3)
	Clean up spacing nits

Signed-off-by: Neil Horman 
CC: "David S. Miller" 
CC: jmaxwell@redhat.com
Tested-by: jmaxwell@redhat.com
Signed-off-by: David S. Miller

netpoll: warn on netpoll_send_udp users who haven't disabled irqs

2015-08-28T23:24:54+00:00

Make sure we catch future netpoll_send_udp users who use it without
disabling irqs and also as a hint for poll_controller users.

Signed-off-by: Nikolay Aleksandrov 
Signed-off-by: David S. Miller

net: rename vlan_tx_* helpers since "tx" is misleading there

2015-01-13T22:51:08+00:00

The same macros are used for rx as well. So rename it.

Signed-off-by: Jiri Pirko 
Signed-off-by: David S. Miller

vlan: introduce *vlan_hwaccel_push_inside helpers

2014-11-21T19:20:17+00:00

Use them to push skb->vlan_tci into the payload and avoid code
duplication.

Signed-off-by: Jiri Pirko 
Acked-by: Pravin B Shelar 
Signed-off-by: David S. Miller

vlan: rename __vlan_put_tag to vlan_insert_tag_set_proto

2014-11-21T19:20:17+00:00

Name fits better. Plus there's going to be introduced
__vlan_insert_tag later on.

Signed-off-by: Jiri Pirko 
Acked-by: Pravin B Shelar 
Signed-off-by: David S. Miller

net: Pass a "more" indication down into netdev_start_xmit() code paths.

2014-09-02T00:39:55+00:00

For now it will always be false.

Signed-off-by: David S. Miller

net: Do txq_trans_update() in netdev_start_xmit()

2014-09-02T00:39:55+00:00

That way we don't have to audit every call site to make sure it is
doing this properly.

Signed-off-by: David S. Miller