linux-toradex.git/net/core/netpoll.c, branch v2.6.18

[NET] netpoll: break recursive loop in netpoll rx path

2006-06-26T07:04:27+00:00

The netpoll system currently has a rx to tx path via:

netpoll_rx
 __netpoll_rx
  arp_reply
   netpoll_send_skb
    dev->hard_start_tx

This rx->tx loop places network drivers at risk of inadvertently causing a
deadlock or BUG halt by recursively trying to acquire a spinlock that is
used in both their rx and tx paths (this problem was origionally reported
to me in the 3c59x driver, which shares a spinlock between the
boomerang_interrupt and boomerang_start_xmit routines).

This patch breaks this loop, by queueing arp frames, so that they can be
responded to after all receive operations have been completed.  Tested by
myself and the reported with successful results.

Specifically it was tested with netdump.  Heres the BZ with details:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=194055

Signed-off-by: Neil Horman 
Acked-by: Matt Mackall 
Signed-off-by: Andrew Morton 
Signed-off-by: David S. Miller

[NET] netpoll: don't spin forever sending to stopped queues

2006-06-26T07:03:40+00:00

When transmitting a skb in netpoll_send_skb(), only retry a limited number
of times if the device queue is stopped.

Signed-off-by: Jeremy Fitzhardinge 
Acked-by: Matt Mackall 
Signed-off-by: Andrew Morton 
Signed-off-by: David S. Miller

[NET]: Add netif_tx_lock

2006-06-18T04:30:14+00:00

Various drivers use xmit_lock internally to synchronise with their
transmission routines.  They do so without setting xmit_lock_owner.
This is fine as long as netpoll is not in use.

With netpoll it is possible for deadlocks to occur if xmit_lock_owner
isn't set.  This is because if a printk occurs while xmit_lock is held
and xmit_lock_owner is not set can cause netpoll to attempt to take
xmit_lock recursively.

While it is possible to resolve this by getting netpoll to use
trylock, it is suboptimal because netpoll's sole objective is to
maximise the chance of getting the printk out on the wire.  So
delaying or dropping the message is to be avoided as much as possible.

So the only alternative is to always set xmit_lock_owner.  The
following patch does this by introducing the netif_tx_lock family of
functions that take care of setting/unsetting xmit_lock_owner.

I renamed xmit_lock to _xmit_lock to indicate that it should not be
used directly.  I didn't provide irq versions of the netif_tx_lock
functions since xmit_lock is meant to be a BH-disabling lock.

This is pretty much a straight text substitution except for a small
bug fix in winbond.  It currently uses
netif_stop_queue/spin_unlock_wait to stop transmission.  This is
unsafe as an IRQ can potentially wake up the queue.  So it is safer to
use netif_tx_disable.

The hamradio bits used spin_lock_irq but it is unnecessary as
xmit_lock must never be taken in an IRQ handler.

Signed-off-by: Herbert Xu 
Signed-off-by: David S. Miller

[NET]: Convert RTNL to mutex.

2006-03-21T06:23:58+00:00

This patch turns the RTNL from a semaphore to a new 2.6.16 mutex and
gets rid of some of the leftover legacy.

Signed-off-by: Stephen Hemminger 
Signed-off-by: David S. Miller

[NET]: Use is_zero_ether_addr() in net/core/netpoll.c

2006-01-17T23:15:38+00:00

This replaces a memcmp() with is_zero_ether_addr().

Signed-off-by: Kris Katterjohn 
Signed-off-by: David S. Miller

[INET_SOCK]: Move struct inet_sock & helper functions to net/inet_sock.h

2006-01-03T21:11:21+00:00

To help in reducing the number of include dependencies, several files were
touched as they were getting needed headers indirectly for stuff they use.

Thanks also to Alan Menegotto for pointing out that net/dccp/proto.c had
linux/dccp.h include twice.

Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: David S. Miller

[NET]: Detect hardware rx checksum faults correctly

2005-11-10T21:01:24+00:00

Here is the patch that introduces the generic skb_checksum_complete
which also checks for hardware RX checksum faults.  If that happens,
it'll call netdev_rx_csum_fault which currently prints out a stack
trace with the device name.  In future it can turn off RX checksum.

I've converted every spot under net/ that does RX checksum checks to
use skb_checksum_complete or __skb_checksum_complete with the
exceptions of:

* Those places where checksums are done bit by bit.  These will call
netdev_rx_csum_fault directly.

* The following have not been completely checked/converted:

ipmr
ip_vs
netfilter
dccp

This patch is based on patches and suggestions from Stephen Hemminger
and David S. Miller.

Signed-off-by: Herbert Xu 
Signed-off-by: David S. Miller

[IPV4]: Replace __in_dev_get with __in_dev_get_rcu/rtnl

2005-10-03T21:35:55+00:00

The following patch renames __in_dev_get() to __in_dev_get_rtnl() and
introduces __in_dev_get_rcu() to cover the second case.

1) RCU with refcnt should use in_dev_get().
2) RCU without refcnt should use __in_dev_get_rcu().
3) All others must hold RTNL and use __in_dev_get_rtnl().

There is one exception in net/ipv4/route.c which is in fact a pre-existing
race condition.  I've marked it as such so that we remember to fix it.

This patch is based on suggestions and prior work by Suzanne Wood and
Paul McKenney.

Signed-off-by: Herbert Xu 
Signed-off-by: David S. Miller

[PATCH] more SPIN_LOCK_UNLOCKED -> DEFINE_SPINLOCK conversions

2005-09-09T21:03:48+00:00

This converts the final 20 DEFINE_SPINLOCK holdouts.  (another 580 places
are already using DEFINE_SPINLOCK).  Build tested on x86.

Signed-off-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[NETPOLL]: remove unused variable

2005-08-12T02:28:05+00:00

Remove unused variable

Signed-off-by: Matt Mackall 
Signed-off-by: David S. Miller