linux-stable.git/net/core/netpoll.c, branch v3.9

netpoll: fix smatch warnings in netpoll core code

2013-02-13T16:56:46+00:00

Dan Carpenter contacted me with some notes regarding some smatch warnings in the
netpoll code, some of which I introduced with my recent netpoll locking fixes,
some which were there prior.   Specifically they were:

net-next/net/core/netpoll.c:243 netpoll_poll_dev() warn: inconsistent
  returns mutex:&ni->dev_lock: locked (213,217) unlocked (210,243)
net-next/net/core/netpoll.c:706 netpoll_neigh_reply() warn: potential
  pointer math issue ('skb_transport_header(send_skb)' is a 128 bit pointer)

This patch corrects the locking imbalance (the first error), and adds some
parenthesis to correct the second error.  Tested by myself. Applies to net-next

Signed-off-by: Neil Horman 
CC: Dan Carpenter 
CC: "David S. Miller" 
Signed-off-by: David S. Miller

netpoll: cleanup sparse warnings

2013-02-12T00:19:58+00:00

With my recent commit I introduced two sparse warnings.  Looking closer there
were a few more in the same file, so I fixed them all up.  Basic rcu pointer
dereferencing suff.

I've validated these changes using CONFIG_PROVE_RCU while starting and stopping
netconsole repeatedly in bonded and non-bonded configurations

Signed-off-by: Neil Horman 
CC: fengguang.wu@intel.com
CC: David Miller 
CC: eric.dumazet@gmail.com

Signed-off-by: David S. Miller

netpoll: Fix __netpoll_rcu_free so that it can hold the rtnl lock

2013-02-12T00:19:33+00:00

__netpoll_rcu_free is used to free netpoll structures when the rtnl_lock is
already held.  The mechanism is used to asynchronously call __netpoll_cleanup
outside of the holding of the rtnl_lock, so as to avoid deadlock.
Unfortunately, __netpoll_cleanup modifies pointers (dev->np), which means the
rtnl_lock must be held while calling it.  Further, it cannot be held, because
rcu callbacks may be issued in softirq contexts, which cannot sleep.

Fix this by converting the rcu callback to a work queue that is guaranteed to
get scheduled in process context, so that we can hold the rtnl properly while
calling __netpoll_cleanup

Tested successfully by myself.

Signed-off-by: Neil Horman 
CC: "David S. Miller" 
CC: Cong Wang 
CC: Eric Dumazet 
Signed-off-by: David S. Miller

netpoll: protect napi_poll and poll_controller during dev_[open|close]

2013-02-06T20:45:03+00:00

Ivan Vercera was recently backporting commit
9c13cb8bb477a83b9a3c9e5a5478a4e21294a760 to a RHEL kernel, and I noticed that,
while this patch protects the tg3 driver from having its ndo_poll_controller
routine called during device initalization, it does nothing for the driver
during shutdown. I.e. it would be entirely possible to have the
ndo_poll_controller method (or subsequently the ndo_poll) routine called for a
driver in the netpoll path on CPU A while in parallel on CPU B, the ndo_close or
ndo_open routine could be called.  Given that the two latter routines tend to
initizlize and free many data structures that the former two rely on, the result
can easily be data corruption or various other crashes.  Furthermore, it seems
that this is potentially a problem with all net drivers that support netpoll,
and so this should ideally be fixed in a common path.

As Ben H Pointed out to me, we can't preform dev_open/dev_close in atomic
context, so I've come up with this solution.  We can use a mutex to sleep in
open/close paths and just do a mutex_trylock in the napi poll path and abandon
the poll attempt if we're locked, as we'll just retry the poll on the next send
anyway.

I've tested this here by flooding netconsole with messages on a system whos nic
driver I modfied to periodically return NETDEV_TX_BUSY, so that the netpoll tx
workqueue would be forced to send frames and poll the device.  While this was
going on I rapidly ifdown/up'ed the interface and watched for any problems.
I've not found any.

Signed-off-by: Neil Horman 
CC: Ivan Vecera 
CC: "David S. Miller" 
CC: Ben Hutchings 
CC: Francois Romieu 
CC: Eric Dumazet 
Signed-off-by: David S. Miller

netpoll: use the net namespace of current process instead of init_net

2013-01-28T23:32:55+00:00

This will allow us to setup netconsole in a different namespace
rather than where init_net is.

Cc: Eric W. Biederman 
Cc: David S. Miller 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

netpoll: use ipv6_addr_equal() to compare ipv6 addr

2013-01-28T23:32:55+00:00

ipv6_addr_equal() is faster.

Cc: David S. Miller 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

netpoll: fix an uninitialized variable

2013-01-23T04:18:59+00:00

Fengguang reported:

   net/core/netpoll.c: In function 'netpoll_setup':
   net/core/netpoll.c:1049:6: warning: 'err' may be used uninitialized in this function [-Wmaybe-uninitialized]

in !CONFIG_IPV6 case, we may error out without initializing
'err'.

Reported-by: Fengguang Wu 
Cc: David S. Miller 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

netpoll: fix a missing dev refcounting

2013-01-17T04:33:06+00:00

__dev_get_by_name() doesn't refcount the network device,
so we have to do this by ourselves. Noticed by Eric.

Cc: Eric Dumazet 
Cc: Jiri Pirko 
Cc: David S. Miller 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

netpoll: fix a rtnl lock assertion failure

2013-01-16T20:26:03+00:00

v4: hold rtnl lock for the whole netpoll_setup()
v3: remove the comment
v2: use RCU read lock

This patch fixes the following warning:

[   72.013864] RTNL: assertion failed at net/core/dev.c (4955)
[   72.017758] Pid: 668, comm: netpoll-prep-v6 Not tainted 3.8.0-rc1+ #474
[   72.019582] Call Trace:
[   72.020295]  [] netdev_master_upper_dev_get+0x35/0x58
[   72.022545]  [] netpoll_setup+0x61/0x340
[   72.024846]  [] store_enabled+0x82/0xc3
[   72.027466]  [] netconsole_target_attr_store+0x35/0x37
[   72.029348]  [] configfs_write_file+0xe2/0x10c
[   72.030959]  [] vfs_write+0xaf/0xf6
[   72.032359]  [] ? sysret_check+0x22/0x5d
[   72.033824]  [] sys_write+0x5c/0x84
[   72.035328]  [] system_call_fastpath+0x16/0x1b

In case of other races, hold rtnl lock for the entire netpoll_setup() function.

Cc: Eric Dumazet 
Cc: Jiri Pirko 
Cc: David S. Miller 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

netpoll: add IPv6 support

2013-01-09T01:56:10+00:00

Currently, netpoll only supports IPv4. This patch adds IPv6
support to netpoll so that we can run netconsole over IPv6 network.

Cc: David S. Miller 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller