linux-toradex.git/include/linux/netpoll.h, branch v4.8-rc1

netpoll: Rename netpoll_rx_enable/disable to netpoll_poll_disable/enable

2014-03-29T21:58:37+00:00

The netpoll_rx_enable and netpoll_rx_disable functions have always
controlled polling the network drivers transmit and receive queues.

Rename them to netpoll_poll_enable and netpoll_poll_disable to make
their functionality clear.

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: David S. Miller

netpoll: Remove gfp parameter from __netpoll_setup

2014-03-29T21:58:37+00:00

The gfp parameter was added in:
commit 47be03a28cc6c80e3aa2b3e8ed6d960ff0c5c0af
Author: Amerigo Wang 
Date:   Fri Aug 10 01:24:37 2012 +0000

    netpoll: use GFP_ATOMIC in slave_enable_netpoll() and __netpoll_setup()

    slave_enable_netpoll() and __netpoll_setup() may be called
    with read_lock() held, so should use GFP_ATOMIC to allocate
    memory. Eric suggested to pass gfp flags to __netpoll_setup().

    Cc: Eric Dumazet 
    Cc: "David S. Miller" 
    Reported-by: Dan Carpenter 
    Signed-off-by: Eric Dumazet 
    Signed-off-by: Cong Wang 
    Signed-off-by: David S. Miller 

The reason for the gfp parameter was removed in:
commit c4cdef9b7183159c23c7302aaf270d64c549f557
Author: dingtianhong 
Date:   Tue Jul 23 15:25:27 2013 +0800

    bonding: don't call slave_xxx_netpoll under spinlocks

    The slave_xxx_netpoll will call synchronize_rcu_bh(),
    so the function may schedule and sleep, it should't be
    called under spinlocks.

    bond_netpoll_setup() and bond_netpoll_cleanup() are always
    protected by rtnl lock, it is no need to take the read lock,
    as the slave list couldn't be changed outside rtnl lock.

    Signed-off-by: Ding Tianhong 
    Cc: Jay Vosburgh 
    Cc: Andy Gospodarek 
    Signed-off-by: David S. Miller 

Nothing else that calls __netpoll_setup or ndo_netpoll_setup
requires a gfp paramter, so remove the gfp parameter from both
of these functions making the code clearer.

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: David S. Miller

netpoll: Remove dead packet receive code (CONFIG_NETPOLL_TRAP)

2014-03-17T19:48:12+00:00

The netpoll packet receive code only becomes active if the netpoll
rx_skb_hook is implemented, and there is not a single implementation
of the netpoll rx_skb_hook in the kernel.

All of the out of tree implementations I have found all call
netpoll_poll which was removed from the kernel in 2011, so this
change should not add any additional breakage.

There are problems with the netpoll packet receive code.  __netpoll_rx
does not call dev_kfree_skb_irq or dev_kfree_skb_any in hard irq
context.  netpoll_neigh_reply leaks every skb it receives.  Reception
of packets does not work successfully on stacked devices (aka bonding,
team, bridge, and vlans).

Given that the netpoll packet receive code is buggy, there are no
out of tree users that will be merged soon, and the code has
not been used for in tree for a decade let's just remove it.

Reverting this commit can server as a starting point for anyone
who wants to resurrect netpoll packet reception support.

Acked-by: Eric Dumazet 
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: David S. Miller

netpoll: Move all receive processing under CONFIG_NETPOLL_TRAP

2014-03-17T19:48:12+00:00

Make rx_skb_hook, and rx in struct netpoll depend on
CONFIG_NETPOLL_TRAP Make rx_lock, rx_np, and neigh_tx in struct
netpoll_info depend on CONFIG_NETPOLL_TRAP

Make the functions netpoll_rx_on, netpoll_rx, and netpoll_receive_skb
no-ops when CONFIG_NETPOLL_TRAP is not set.

Only build netpoll_neigh_reply, checksum_udp service_neigh_queue,
pkt_is_ns, and __netpoll_rx when CONFIG_NETPOLL_TRAP is defined.

Add helper functions netpoll_trap_setup, netpoll_trap_setup_info,
netpoll_trap_cleanup, and netpoll_trap_cleanup_info that initialize
and cleanup the struct netpoll and struct netpoll_info receive
specific fields when CONFIG_NETPOLL_TRAP is enabled and do nothing
otherwise.

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: David S. Miller

netpoll: Move netpoll_trap under CONFIG_NETPOLL_TRAP

2014-03-17T19:47:22+00:00

Now that we no longer need to receive packets to safely drain the
network drivers receive queue move netpoll_trap and netpoll_set_trap
under CONFIG_NETPOLL_TRAP

Making netpoll_trap and netpoll_set_trap noop inline functions
when CONFIG_NETPOLL_TRAP is not set.

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: David S. Miller

netpoll: Don't drop all received packets.

2014-03-17T19:47:22+00:00

Change the strategy of netpoll from dropping all packets received
during netpoll_poll_dev to calling napi poll with a budget of 0
(to avoid processing drivers rx queue), and to ignore packets received
with netif_rx (those will safely be placed on the backlog queue).

All of the netpoll supporting drivers have been reviewed to ensure
either thay use netif_rx or that a budget of 0 is supported by their
napi poll routine and that a budget of 0 will not process the drivers
rx queues.

Not dropping packets makes NETPOLL_RX_DROP unnecesary so it is removed.

npinfo->rx_flags is removed  as rx_flags with just the NETPOLL_RX_ENABLED
flag becomes just a redundant mirror of list_empty(&npinfo->rx_np).

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: David S. Miller

netpoll: Add netpoll_rx_processing

2014-03-17T19:47:22+00:00

Add a helper netpoll_rx_processing that reports when netpoll has
receive side processing to perform.

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: David S. Miller

netpoll: fix rx_hook() interface by passing the skb

2013-10-25T23:26:58+00:00

Right now skb->data is passed to rx_hook() even if the skb
has not been linearised and without giving rx_hook() a way
to linearise it.

Change the rx_hook() interface and make it accept the skb
and the offset to the UDP payload as arguments. rx_hook() is
also renamed to rx_skb_hook() to ensure that out of the tree
users notice the API change.

In this way any rx_skb_hook() implementation can perform all
the needed operations to properly (and safely) access the
skb data.

Signed-off-by: Antonio Quartulli 
Signed-off-by: David S. Miller

netpoll: remove return value from netpoll_rx_disable()

2013-05-28T06:18:50+00:00

The netpoll_rx_disable() will always return 0, it is no use and looks wordy,
so remove the unnecessary code and get rid of it in _dev_open and _dev_close.

Signed-off-by: Ding Tianhong 
Signed-off-by: David S. Miller

netpoll: convert mutex into a semaphore

2013-05-01T19:00:24+00:00

Bart Van Assche recently reported a warning to me:

  [] warn_slowpath_common+0x7f/0xc0
[] warn_slowpath_null+0x1a/0x20
[] mutex_trylock+0x16d/0x180
[] netpoll_poll_dev+0x49/0xc30
[] ? __alloc_skb+0x82/0x2a0
[] netpoll_send_skb_on_dev+0x265/0x410
[] netpoll_send_udp+0x28a/0x3a0
[] ? write_msg+0x53/0x110 [netconsole]
[] write_msg+0xcf/0x110 [netconsole]
[] call_console_drivers.constprop.17+0xa1/0x1c0
[] console_unlock+0x2d6/0x450
[] vprintk_emit+0x1ee/0x510
[] printk+0x4d/0x4f
[] scsi_print_command+0x7d/0xe0 [scsi_mod]

This resulted from my commit ca99ca14c which introduced a mutex_trylock
operation in a path that could execute in interrupt context.  When mutex
debugging is enabled, the above warns the user when we are in fact
exectuting in interrupt context
interrupt context.

After some discussion, It seems that a semaphore is the proper mechanism to use
here.  While mutexes are defined to be unusable in interrupt context, no such
condition exists for semaphores (save for the fact that the non blocking api
calls, like up and down_trylock must be used when in irq context).

Signed-off-by: Neil Horman 
Reported-by: Bart Van Assche 
CC: Bart Van Assche 
CC: David Miller 
CC: netdev@vger.kernel.org
Signed-off-by: David S. Miller