Remove the __resched_legal() check: it is conceptually broken.  The biggest
problem it had is that it can mask buggy cond_resched() calls.  A
cond_resched() call is only legal if we are not in an atomic context, with
two narrow exceptions:

 - if the system is booting
 - a reacquire_kernel_lock() down() done while PREEMPT_ACTIVE is set

But __resched_legal() hid this and just silently returned whenever
these primitives were called from invalid contexts. (Same goes for
cond_resched_locked() and cond_resched_softirq()).

Furthermore, the __legal_resched(0) call was buggy in that it caused
unnecessarily long softirq latencies via cond_resched_softirq().  (which is
only called from softirq-off sections, hence the code did nothing.)

The fix is to resurrect the efficiency of the might_sleep checks and to
only allow the narrow exceptions.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
[chrisw: backport to 2.6.19.2]
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

move_task_off_dead_cpu() requires interrupts to be disabled, while
migrate_dead() calls it with enabled interrupts.  Added appropriate
comments to functions and added BUG_ON(!irqs_disabled()) into
double_rq_lock() and double_lock_balance() which are the origin sources of
such bugs.

Signed-off-by: Kirill Korotaev <dev@openvz.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

This patch fixes a regression in 2.6.19 in which the use of multiple
krb5 mounts against the same NFS server may result in an Oops on
unmount. The Oops is due to the fact that multiple NFS krb5 clients may
end up inadvertently sharing the same rpc_pipefs upcall pipe. The first
client to 'umount' will unlink that shared pipe, causing an Oops.

The solution is to give each client their own upcall pipe. This fix has
been in mainline since 2.6.20-rc1.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
[chrisw: backport to 2.6.19.2]
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

When the packet counter of a connection is zero a division by zero
occurs in div64_64(). Fix that by using zero as average value, which
is correct as long as the packet counter didn't overflow, at which
point we have lost anyway.

Additionally we're probably going to go back to 64 bit counters
in 2.6.21.

Based on patch from Jonas Berlin <xkr47@outerspace.dyndns.org>,
with suggestions from KOVACS Krisztian <hidden@balabit.hu>.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

I encountered a kernel panic with my test program, which is a very
simple IPv6 client-server program.

The server side sets IPV6_RECVPKTINFO on a listening socket, and the
client side just sends a message to the server.  Then the kernel panic
occurs on the server.  (If you need the test program, please let me
know. I can provide it.)

This problem happens because a skb is forcibly freed in
tcp_rcv_state_process().

When a socket in listening state(TCP_LISTEN) receives a syn packet,
then tcp_v6_conn_request() will be called from
tcp_rcv_state_process().  If the tcp_v6_conn_request() successfully
returns, the skb would be discarded by __kfree_skb().

However, in case of a listening socket which was already set
IPV6_RECVPKTINFO, an address of the skb will be stored in
treq->pktopts and a ref count of the skb will be incremented in
tcp_v6_conn_request().  But, even if the skb is still in use, the skb
will be freed.  Then someone still using the freed skb will cause the
kernel panic.

I suggest to use kfree_skb() instead of __kfree_skb().

Signed-off-by: Masayuki Nakagawa <nakagawa.msy@ncos.nec.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

The sorting of SACK blocks actually munges them rather than sort,
causing the TCP stack to ignore some SACK information and breaking the
assumption of ordered SACK blocks after sorting.

The sort takes the data from a second buffer which isn't moved causing
subsequent data moves to occur from the wrong location. The fix is to
use a temporary buffer as a normal sort does.

Signed-off-By: Baruch Even <baruch@ev-en.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

The patch "Replace CHECKSUM_HW by CHECKSUM_PARTIAL/CHECKSUM_COMPLETE"
changed to unconditional copying of ip_summed field from collapsed
skb. This patch reverts this change.

The majority of substantial work including heavy testing
and diagnosing by: Michael Tokarev <mjt@tls.msk.ru>
Possible reasons pointed by: Herbert Xu and Patrick McHardy.

Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

If the device is down, invoking the device hard header callbacks
is not legal, so check it early.

Based upon a shaper OOPS report from Frederik Deweerdt.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

This fixes a bug introduced by:

commit fda9ef5d679b07c9d9097aaf6ef7f069d794a8f9
Author: Dmitry Mishin <dim@openvz.org>
Date:   Thu Aug 31 15:28:39 2006 -0700

    [NET]: Fix sk->sk_filter field access

sk_run_filter() returns either 0 or an unsigned 32-bit
length which says how much of the packet to retain.
If that 32-bit unsigned integer is larger than the packet,
this is fine we just leave the packet unchanged.

The above commit caused all filter return values which
were negative when interpreted as a signed integer to
indicate a packet drop, which is wrong.

Based upon a report and initial patch by Raivis Bucis.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>