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Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6
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* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1429 commits)
  net: Allow dependancies of FDDI & Tokenring to be modular.
  igb: Fix build warning when DCA is disabled.
  net: Fix warning fallout from recent NAPI interface changes.
  gro: Fix potential use after free
  sfc: If AN is enabled, always read speed/duplex from the AN advertising bits
  sfc: When disabling the NIC, close the device rather than unregistering it
  sfc: SFT9001: Add cable diagnostics
  sfc: Add support for multiple PHY self-tests
  sfc: Merge top-level functions for self-tests
  sfc: Clean up PHY mode management in loopback self-test
  sfc: Fix unreliable link detection in some loopback modes
  sfc: Generate unique names for per-NIC workqueues
  802.3ad: use standard ethhdr instead of ad_header
  802.3ad: generalize out mac address initializer
  802.3ad: initialize ports LACPDU from const initializer
  802.3ad: remove typedef around ad_system
  802.3ad: turn ports is_individual into a bool
  802.3ad: turn ports is_enabled into a bool
  802.3ad: make ntt bool
  ixgbe: Fix set_ringparam in ixgbe to use the same memory pools.
  ...

Fixed trivial IPv4/6 address printing conflicts in fs/cifs/connect.c due
to the conversion to %pI (in this networking merge) and the addition of
doing IPv6 addresses (from the earlier merge of CIFS).
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torvalds committed Dec 28, 2008
2 parents 54a696b + eb56092 commit 0191b62
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2 changes: 1 addition & 1 deletion Documentation/DocBook/Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@
# To add a new book the only step required is to add the book to the
# list of DOCBOOKS.

DOCBOOKS := wanbook.xml z8530book.xml mcabook.xml \
DOCBOOKS := z8530book.xml mcabook.xml \
kernel-hacking.xml kernel-locking.xml deviceiobook.xml \
procfs-guide.xml writing_usb_driver.xml networking.xml \
kernel-api.xml filesystems.xml lsm.xml usb.xml kgdb.xml \
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3 changes: 0 additions & 3 deletions Documentation/DocBook/networking.tmpl
Original file line number Diff line number Diff line change
Expand Up @@ -98,9 +98,6 @@
X!Enet/core/wireless.c
</sect1>
-->
<sect1><title>Synchronous PPP</title>
!Edrivers/net/wan/syncppp.c
</sect1>
</chapter>

</book>
99 changes: 0 additions & 99 deletions Documentation/DocBook/wanbook.tmpl

This file was deleted.

167 changes: 167 additions & 0 deletions Documentation/RCU/rculist_nulls.txt
Original file line number Diff line number Diff line change
@@ -0,0 +1,167 @@
Using hlist_nulls to protect read-mostly linked lists and
objects using SLAB_DESTROY_BY_RCU allocations.

Please read the basics in Documentation/RCU/listRCU.txt

Using special makers (called 'nulls') is a convenient way
to solve following problem :

A typical RCU linked list managing objects which are
allocated with SLAB_DESTROY_BY_RCU kmem_cache can
use following algos :

1) Lookup algo
--------------
rcu_read_lock()
begin:
obj = lockless_lookup(key);
if (obj) {
if (!try_get_ref(obj)) // might fail for free objects
goto begin;
/*
* Because a writer could delete object, and a writer could
* reuse these object before the RCU grace period, we
* must check key after geting the reference on object
*/
if (obj->key != key) { // not the object we expected
put_ref(obj);
goto begin;
}
}
rcu_read_unlock();

Beware that lockless_lookup(key) cannot use traditional hlist_for_each_entry_rcu()
but a version with an additional memory barrier (smp_rmb())

lockless_lookup(key)
{
struct hlist_node *node, *next;
for (pos = rcu_dereference((head)->first);
pos && ({ next = pos->next; smp_rmb(); prefetch(next); 1; }) &&
({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; });
pos = rcu_dereference(next))
if (obj->key == key)
return obj;
return NULL;

And note the traditional hlist_for_each_entry_rcu() misses this smp_rmb() :

struct hlist_node *node;
for (pos = rcu_dereference((head)->first);
pos && ({ prefetch(pos->next); 1; }) &&
({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; });
pos = rcu_dereference(pos->next))
if (obj->key == key)
return obj;
return NULL;
}

Quoting Corey Minyard :

"If the object is moved from one list to another list in-between the
time the hash is calculated and the next field is accessed, and the
object has moved to the end of a new list, the traversal will not
complete properly on the list it should have, since the object will
be on the end of the new list and there's not a way to tell it's on a
new list and restart the list traversal. I think that this can be
solved by pre-fetching the "next" field (with proper barriers) before
checking the key."

2) Insert algo :
----------------

We need to make sure a reader cannot read the new 'obj->obj_next' value
and previous value of 'obj->key'. Or else, an item could be deleted
from a chain, and inserted into another chain. If new chain was empty
before the move, 'next' pointer is NULL, and lockless reader can
not detect it missed following items in original chain.

/*
* Please note that new inserts are done at the head of list,
* not in the middle or end.
*/
obj = kmem_cache_alloc(...);
lock_chain(); // typically a spin_lock()
obj->key = key;
atomic_inc(&obj->refcnt);
/*
* we need to make sure obj->key is updated before obj->next
*/
smp_wmb();
hlist_add_head_rcu(&obj->obj_node, list);
unlock_chain(); // typically a spin_unlock()


3) Remove algo
--------------
Nothing special here, we can use a standard RCU hlist deletion.
But thanks to SLAB_DESTROY_BY_RCU, beware a deleted object can be reused
very very fast (before the end of RCU grace period)

if (put_last_reference_on(obj) {
lock_chain(); // typically a spin_lock()
hlist_del_init_rcu(&obj->obj_node);
unlock_chain(); // typically a spin_unlock()
kmem_cache_free(cachep, obj);
}



--------------------------------------------------------------------------
With hlist_nulls we can avoid extra smp_rmb() in lockless_lookup()
and extra smp_wmb() in insert function.

For example, if we choose to store the slot number as the 'nulls'
end-of-list marker for each slot of the hash table, we can detect
a race (some writer did a delete and/or a move of an object
to another chain) checking the final 'nulls' value if
the lookup met the end of chain. If final 'nulls' value
is not the slot number, then we must restart the lookup at
the begining. If the object was moved to same chain,
then the reader doesnt care : It might eventually
scan the list again without harm.


1) lookup algo

head = &table[slot];
rcu_read_lock();
begin:
hlist_nulls_for_each_entry_rcu(obj, node, head, member) {
if (obj->key == key) {
if (!try_get_ref(obj)) // might fail for free objects
goto begin;
if (obj->key != key) { // not the object we expected
put_ref(obj);
goto begin;
}
goto out;
}
/*
* if the nulls value we got at the end of this lookup is
* not the expected one, we must restart lookup.
* We probably met an item that was moved to another chain.
*/
if (get_nulls_value(node) != slot)
goto begin;
obj = NULL;

out:
rcu_read_unlock();

2) Insert function :
--------------------

/*
* Please note that new inserts are done at the head of list,
* not in the middle or end.
*/
obj = kmem_cache_alloc(cachep);
lock_chain(); // typically a spin_lock()
obj->key = key;
atomic_set(&obj->refcnt, 1);
/*
* insert obj in RCU way (readers might be traversing chain)
*/
hlist_nulls_add_head_rcu(&obj->obj_node, list);
unlock_chain(); // typically a spin_unlock()
7 changes: 0 additions & 7 deletions Documentation/feature-removal-schedule.txt
Original file line number Diff line number Diff line change
Expand Up @@ -120,13 +120,6 @@ Who: Christoph Hellwig <[email protected]>

---------------------------

What: eepro100 network driver
When: January 2007
Why: replaced by the e100 driver
Who: Adrian Bunk <[email protected]>

---------------------------

What: Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
(temporary transition config option provided until then)
The transition config option will also be removed at the same time.
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2 changes: 1 addition & 1 deletion Documentation/networking/README.ipw2200
Original file line number Diff line number Diff line change
Expand Up @@ -147,7 +147,7 @@ Where the supported parameter are:
driver. If disabled, the driver will not attempt to scan
for and associate to a network until it has been configured with
one or more properties for the target network, for example configuring
the network SSID. Default is 1 (auto-associate)
the network SSID. Default is 0 (do not auto-associate)

Example: % modprobe ipw2200 associate=0

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