Skip to content

Commit

Permalink
Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/…
Browse files Browse the repository at this point in the history
…davem/net-2.6

Conflicts:
	drivers/net/stmmac/stmmac_main.c
	drivers/net/wireless/wl12xx/wl1271_cmd.c
	drivers/net/wireless/wl12xx/wl1271_main.c
	drivers/net/wireless/wl12xx/wl1271_spi.c
	net/core/ethtool.c
	net/mac80211/scan.c
  • Loading branch information
davem330 committed Apr 11, 2010
2 parents e4077e0 + 4a1032f commit 871039f
Show file tree
Hide file tree
Showing 4,645 changed files with 13,577 additions and 6,319 deletions.
The diff you're trying to view is too large. We only load the first 3000 changed files.
File renamed without changes.
13 changes: 13 additions & 0 deletions Documentation/DocBook/tracepoint.tmpl
Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,15 @@
</address>
</affiliation>
</author>
<author>
<firstname>William</firstname>
<surname>Cohen</surname>
<affiliation>
<address>
<email>[email protected]</email>
</address>
</affiliation>
</author>
</authorgroup>

<legalnotice>
Expand Down Expand Up @@ -91,4 +100,8 @@
!Iinclude/trace/events/signal.h
</chapter>

<chapter id="block">
<title>Block IO</title>
!Iinclude/trace/events/block.h
</chapter>
</book>
4 changes: 2 additions & 2 deletions Documentation/block/biodoc.txt
Original file line number Diff line number Diff line change
Expand Up @@ -1162,8 +1162,8 @@ where a driver received a request ala this before:

As mentioned, there is no virtual mapping of a bio. For DMA, this is
not a problem as the driver probably never will need a virtual mapping.
Instead it needs a bus mapping (pci_map_page for a single segment or
use blk_rq_map_sg for scatter gather) to be able to ship it to the driver. For
Instead it needs a bus mapping (dma_map_page for a single segment or
use dma_map_sg for scatter gather) to be able to ship it to the driver. For
PIO drivers (or drivers that need to revert to PIO transfer once in a
while (IDE for example)), where the CPU is doing the actual data
transfer a virtual mapping is needed. If the driver supports highmem I/O,
Expand Down
2 changes: 1 addition & 1 deletion Documentation/cgroups/memory.txt
Original file line number Diff line number Diff line change
Expand Up @@ -340,7 +340,7 @@ Note:
5.3 swappiness
Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.

Following cgroups' swapiness can't be changed.
Following cgroups' swappiness can't be changed.
- root cgroup (uses /proc/sys/vm/swappiness).
- a cgroup which uses hierarchy and it has child cgroup.
- a cgroup which uses hierarchy and not the root of hierarchy.
Expand Down
234 changes: 234 additions & 0 deletions Documentation/circular-buffers.txt
Original file line number Diff line number Diff line change
@@ -0,0 +1,234 @@
================
CIRCULAR BUFFERS
================

By: David Howells <[email protected]>
Paul E. McKenney <[email protected]>


Linux provides a number of features that can be used to implement circular
buffering. There are two sets of such features:

(1) Convenience functions for determining information about power-of-2 sized
buffers.

(2) Memory barriers for when the producer and the consumer of objects in the
buffer don't want to share a lock.

To use these facilities, as discussed below, there needs to be just one
producer and just one consumer. It is possible to handle multiple producers by
serialising them, and to handle multiple consumers by serialising them.


Contents:

(*) What is a circular buffer?

(*) Measuring power-of-2 buffers.

(*) Using memory barriers with circular buffers.
- The producer.
- The consumer.


==========================
WHAT IS A CIRCULAR BUFFER?
==========================

First of all, what is a circular buffer? A circular buffer is a buffer of
fixed, finite size into which there are two indices:

(1) A 'head' index - the point at which the producer inserts items into the
buffer.

(2) A 'tail' index - the point at which the consumer finds the next item in
the buffer.

Typically when the tail pointer is equal to the head pointer, the buffer is
empty; and the buffer is full when the head pointer is one less than the tail
pointer.

The head index is incremented when items are added, and the tail index when
items are removed. The tail index should never jump the head index, and both
indices should be wrapped to 0 when they reach the end of the buffer, thus
allowing an infinite amount of data to flow through the buffer.

Typically, items will all be of the same unit size, but this isn't strictly
required to use the techniques below. The indices can be increased by more
than 1 if multiple items or variable-sized items are to be included in the
buffer, provided that neither index overtakes the other. The implementer must
be careful, however, as a region more than one unit in size may wrap the end of
the buffer and be broken into two segments.


============================
MEASURING POWER-OF-2 BUFFERS
============================

Calculation of the occupancy or the remaining capacity of an arbitrarily sized
circular buffer would normally be a slow operation, requiring the use of a
modulus (divide) instruction. However, if the buffer is of a power-of-2 size,
then a much quicker bitwise-AND instruction can be used instead.

Linux provides a set of macros for handling power-of-2 circular buffers. These
can be made use of by:

#include <linux/circ_buf.h>

The macros are:

(*) Measure the remaining capacity of a buffer:

CIRC_SPACE(head_index, tail_index, buffer_size);

This returns the amount of space left in the buffer[1] into which items
can be inserted.


(*) Measure the maximum consecutive immediate space in a buffer:

CIRC_SPACE_TO_END(head_index, tail_index, buffer_size);

This returns the amount of consecutive space left in the buffer[1] into
which items can be immediately inserted without having to wrap back to the
beginning of the buffer.


(*) Measure the occupancy of a buffer:

CIRC_CNT(head_index, tail_index, buffer_size);

This returns the number of items currently occupying a buffer[2].


(*) Measure the non-wrapping occupancy of a buffer:

CIRC_CNT_TO_END(head_index, tail_index, buffer_size);

This returns the number of consecutive items[2] that can be extracted from
the buffer without having to wrap back to the beginning of the buffer.


Each of these macros will nominally return a value between 0 and buffer_size-1,
however:

[1] CIRC_SPACE*() are intended to be used in the producer. To the producer
they will return a lower bound as the producer controls the head index,
but the consumer may still be depleting the buffer on another CPU and
moving the tail index.

To the consumer it will show an upper bound as the producer may be busy
depleting the space.

[2] CIRC_CNT*() are intended to be used in the consumer. To the consumer they
will return a lower bound as the consumer controls the tail index, but the
producer may still be filling the buffer on another CPU and moving the
head index.

To the producer it will show an upper bound as the consumer may be busy
emptying the buffer.

[3] To a third party, the order in which the writes to the indices by the
producer and consumer become visible cannot be guaranteed as they are
independent and may be made on different CPUs - so the result in such a
situation will merely be a guess, and may even be negative.


===========================================
USING MEMORY BARRIERS WITH CIRCULAR BUFFERS
===========================================

By using memory barriers in conjunction with circular buffers, you can avoid
the need to:

(1) use a single lock to govern access to both ends of the buffer, thus
allowing the buffer to be filled and emptied at the same time; and

(2) use atomic counter operations.

There are two sides to this: the producer that fills the buffer, and the
consumer that empties it. Only one thing should be filling a buffer at any one
time, and only one thing should be emptying a buffer at any one time, but the
two sides can operate simultaneously.


THE PRODUCER
------------

The producer will look something like this:

spin_lock(&producer_lock);

unsigned long head = buffer->head;
unsigned long tail = ACCESS_ONCE(buffer->tail);

if (CIRC_SPACE(head, tail, buffer->size) >= 1) {
/* insert one item into the buffer */
struct item *item = buffer[head];

produce_item(item);

smp_wmb(); /* commit the item before incrementing the head */

buffer->head = (head + 1) & (buffer->size - 1);

/* wake_up() will make sure that the head is committed before
* waking anyone up */
wake_up(consumer);
}

spin_unlock(&producer_lock);

This will instruct the CPU that the contents of the new item must be written
before the head index makes it available to the consumer and then instructs the
CPU that the revised head index must be written before the consumer is woken.

Note that wake_up() doesn't have to be the exact mechanism used, but whatever
is used must guarantee a (write) memory barrier between the update of the head
index and the change of state of the consumer, if a change of state occurs.


THE CONSUMER
------------

The consumer will look something like this:

spin_lock(&consumer_lock);

unsigned long head = ACCESS_ONCE(buffer->head);
unsigned long tail = buffer->tail;

if (CIRC_CNT(head, tail, buffer->size) >= 1) {
/* read index before reading contents at that index */
smp_read_barrier_depends();

/* extract one item from the buffer */
struct item *item = buffer[tail];

consume_item(item);

smp_mb(); /* finish reading descriptor before incrementing tail */

buffer->tail = (tail + 1) & (buffer->size - 1);
}

spin_unlock(&consumer_lock);

This will instruct the CPU to make sure the index is up to date before reading
the new item, and then it shall make sure the CPU has finished reading the item
before it writes the new tail pointer, which will erase the item.


Note the use of ACCESS_ONCE() in both algorithms to read the opposition index.
This prevents the compiler from discarding and reloading its cached value -
which some compilers will do across smp_read_barrier_depends(). This isn't
strictly needed if you can be sure that the opposition index will _only_ be
used the once.


===============
FURTHER READING
===============

See also Documentation/memory-barriers.txt for a description of Linux's memory
barrier facilities.
1 change: 1 addition & 0 deletions Documentation/connector/cn_test.c
Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/timer.h>

#include <linux/connector.h>
Expand Down
14 changes: 7 additions & 7 deletions Documentation/fb/imacfb.txt → Documentation/fb/efifb.txt
Original file line number Diff line number Diff line change
@@ -1,9 +1,9 @@

What is imacfb?
What is efifb?
===============

This is a generic EFI platform driver for Intel based Apple computers.
Imacfb is only for EFI booted Intel Macs.
efifb is only for EFI booted Intel Macs.

Supported Hardware
==================
Expand All @@ -16,16 +16,16 @@ MacMini
How to use it?
==============

Imacfb does not have any kind of autodetection of your machine.
efifb does not have any kind of autodetection of your machine.
You have to add the following kernel parameters in your elilo.conf:
Macbook :
video=imacfb:macbook
video=efifb:macbook
MacMini :
video=imacfb:mini
video=efifb:mini
Macbook Pro 15", iMac 17" :
video=imacfb:i17
video=efifb:i17
Macbook Pro 17", iMac 20" :
video=imacfb:i20
video=efifb:i20

--
Edgar Hucek <[email protected]>
2 changes: 2 additions & 0 deletions Documentation/filesystems/00-INDEX
Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,8 @@ befs.txt
- information about the BeOS filesystem for Linux.
bfs.txt
- info for the SCO UnixWare Boot Filesystem (BFS).
ceph.txt
- info for the Ceph Distributed File System
cifs.txt
- description of the CIFS filesystem.
coda.txt
Expand Down
18 changes: 16 additions & 2 deletions Documentation/filesystems/9p.txt
Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,15 @@ For Plan 9 From User Space applications (http://swtch.com/plan9)

mount -t 9p `namespace`/acme /mnt/9 -o trans=unix,uname=$USER

For server running on QEMU host with virtio transport:

mount -t 9p -o trans=virtio <mount_tag> /mnt/9

where mount_tag is the tag associated by the server to each of the exported
mount points. Each 9P export is seen by the client as a virtio device with an
associated "mount_tag" property. Available mount tags can be
seen by reading /sys/bus/virtio/drivers/9pnet_virtio/virtio<n>/mount_tag files.

OPTIONS
=======

Expand All @@ -47,7 +56,7 @@ OPTIONS
fd - used passed file descriptors for connection
(see rfdno and wfdno)
virtio - connect to the next virtio channel available
(from lguest or KVM with trans_virtio module)
(from QEMU with trans_virtio module)
rdma - connect to a specified RDMA channel

uname=name user name to attempt mount as on the remote server. The
Expand Down Expand Up @@ -85,7 +94,12 @@ OPTIONS

port=n port to connect to on the remote server

noextend force legacy mode (no 9p2000.u semantics)
noextend force legacy mode (no 9p2000.u or 9p2000.L semantics)

version=name Select 9P protocol version. Valid options are:
9p2000 - Legacy mode (same as noextend)
9p2000.u - Use 9P2000.u protocol
9p2000.L - Use 9P2000.L protocol

dfltuid attempt to mount as a particular uid

Expand Down
Loading

0 comments on commit 871039f

Please sign in to comment.