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Merge branch 'master' into next

Browse Source 
Conflicts:
	fs/namei.c

Manually merged per:

diff --cc fs/namei.c
index 734f2b5,bbc15c2..0000000
--- a/fs/namei.c
+++ b/fs/namei.c
@@@ -860,9 -848,8 +849,10 @@@ static int __link_path_walk(const char
  		nd->flags |= LOOKUP_CONTINUE;
  		err = exec_permission_lite(inode);
  		if (err == -EAGAIN)
- 			err = vfs_permission(nd, MAY_EXEC);
+ 			err = inode_permission(nd->path.dentry->d_inode,
+ 					       MAY_EXEC);
 +		if (!err)
 +			err = ima_path_check(&nd->path, MAY_EXEC);
   		if (err)
  			break;

@@@ -1525,14 -1506,9 +1509,14 @@@ int may_open(struct path *path, int acc
  		flag &= ~O_TRUNC;
  	}

- 	error = vfs_permission(nd, acc_mode);
+ 	error = inode_permission(inode, acc_mode);
  	if (error)
  		return error;
 +
- 	error = ima_path_check(&nd->path,
++	error = ima_path_check(path,
 +			       acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC));
 +	if (error)
 +		return error;
  	/*
  	 * An append-only file must be opened in append mode for writing.
  	 */

Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
James Morris
2009-02-06 11:01:45 +11:00
parent 8920d5ad6b f01d1d546a
commit cb5629b10d
6302 changed files with 762933 additions and 123441 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
.mailmap
View File

@@ -32,6 +32,7 @@ Christoph Hellwig <hch@lst.de>
Corey Minyard <minyard@acm.org>
David Brownell <david-b@pacbell.net>
David Woodhouse <dwmw2@shinybook.infradead.org>
Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Domen Puncer <domen@coderock.org>
Douglas Gilbert <dougg@torque.net>
Ed L. Cashin <ecashin@coraid.com>

38
CREDITS
View File

@@ -369,10 +369,10 @@ P: 1024/8462A731 4C 55 86 34 44 59 A7 99 2B 97 88 4A 88 9A 0D 97
D: sun4 port, Sparc hacker
N: Hugh Blemings
E: hugh@misc.nu
W: http://misc.nu/hugh/
D: Author and maintainer of the Keyspan USB to Serial drivers
S: Po Box 234
E: hugh@blemings.org
W: http://blemings.org/hugh
D: Original author of the Keyspan USB to serial drivers, random PowerPC hacker
S: PO Box 234
S: Belconnen ACT 2616
S: Australia
@@ -464,6 +464,11 @@ S: 1200 Goldenrod Dr.
S: Nampa, Idaho 83686
S: USA
N: Dirk J. Brandewie
E: dirk.j.brandewie@intel.com
E: linux-wimax@intel.com
D: Intel Wireless WiMAX Connection 2400 SDIO driver
N: Derrick J. Brashear
E: shadow@dementia.org
W: http://www.dementia.org/~shadow
@@ -1681,7 +1686,7 @@ E: ajoshi@shell.unixbox.com
D: fbdev hacking
N: Jesper Juhl
E: jesper.juhl@gmail.com
E: jj@chaosbits.net
D: Various fixes, cleanups and minor features all over the tree.
D: Wrote initial version of the hdaps driver (since passed on to others).
S: Lemnosvej 1, 3.tv
@@ -2119,6 +2124,11 @@ N: H.J. Lu
E: hjl@gnu.ai.mit.edu
D: GCC + libraries hacker
N: Yanir Lubetkin
E: yanirx.lubatkin@intel.com
E: linux-wimax@intel.com
D: Intel Wireless WiMAX Connection 2400 driver
N: Michal Ludvig
E: michal@logix.cz
E: michal.ludvig@asterisk.co.nz
@@ -2693,6 +2703,13 @@ S: RR #5, 497 Pole Line Road
S: Thunder Bay, Ontario
S: CANADA P7C 5M9
N: Inaky Perez-Gonzalez
E: inaky.perez-gonzalez@intel.com
E: linux-wimax@intel.com
E: inakypg@yahoo.com
D: WiMAX stack
D: Intel Wireless WiMAX Connection 2400 driver
N: Yuri Per
E: yuri@pts.mipt.ru
D: Some smbfs fixes
@@ -3769,14 +3786,11 @@ S: The Netherlands
N: David Woodhouse
E: dwmw2@infradead.org
D: ARCnet stuff, Applicom board driver, SO_BINDTODEVICE,
D: some Alpha platform porting from 2.0, Memory Technology Devices,
D: Acquire watchdog timer, PC speaker driver maintenance,
D: JFFS2 file system, Memory Technology Device subsystem,
D: various other stuff that annoyed me by not working.
S: c/o Red Hat Engineering
S: Rustat House
S: 60 Clifton Road
S: Cambridge. CB1 7EG
S: c/o Intel Corporation
S: Pipers Way
S: Swindon. SN3 1RJ
S: England
N: Chris Wright

136
Documentation/ABI/testing/sysfs-class-regulator
View File

@@ -3,8 +3,9 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
state. This holds the regulator output state.
Some regulator directories will contain a field called
state. This reports the regulator enable status, for
regulators which can report that value.
This will be one of the following strings:
@@ -18,7 +19,8 @@ Description:
'disabled' means the regulator output is OFF and is not
supplying power to the system..
'unknown' means software cannot determine the state.
'unknown' means software cannot determine the state, or
the reported state is invalid.
NOTE: this field can be used in conjunction with microvolts
and microamps to determine regulator output levels.
@@ -53,9 +55,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
microvolts. This holds the regulator output voltage setting
measured in microvolts (i.e. E-6 Volts).
measured in microvolts (i.e. E-6 Volts), for regulators
which can report that voltage.
NOTE: This value should not be used to determine the regulator
output voltage level as this value is the same regardless of
@@ -67,9 +70,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
microamps. This holds the regulator output current limit
setting measured in microamps (i.e. E-6 Amps).
setting measured in microamps (i.e. E-6 Amps), for regulators
which can report that current.
NOTE: This value should not be used to determine the regulator
output current level as this value is the same regardless of
@@ -81,8 +85,9 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
opmode. This holds the regulator operating mode setting.
Some regulator directories will contain a field called
opmode. This holds the current regulator operating mode,
for regulators which can report it.
The opmode value can be one of the following strings:
@@ -92,7 +97,7 @@ Description:
'standby'
'unknown'
The modes are described in include/linux/regulator/regulator.h
The modes are described in include/linux/regulator/consumer.h
NOTE: This value should not be used to determine the regulator
output operating mode as this value is the same regardless of
@@ -104,9 +109,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
min_microvolts. This holds the minimum safe working regulator
output voltage setting for this domain measured in microvolts.
output voltage setting for this domain measured in microvolts,
for regulators which support voltage constraints.
NOTE: this will return the string 'constraint not defined' if
the power domain has no min microvolts constraint defined by
@@ -118,9 +124,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
max_microvolts. This holds the maximum safe working regulator
output voltage setting for this domain measured in microvolts.
output voltage setting for this domain measured in microvolts,
for regulators which support voltage constraints.
NOTE: this will return the string 'constraint not defined' if
the power domain has no max microvolts constraint defined by
@@ -132,10 +139,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
min_microamps. This holds the minimum safe working regulator
output current limit setting for this domain measured in
microamps.
microamps, for regulators which support current constraints.
NOTE: this will return the string 'constraint not defined' if
the power domain has no min microamps constraint defined by
@@ -147,10 +154,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
max_microamps. This holds the maximum safe working regulator
output current limit setting for this domain measured in
microamps.
microamps, for regulators which support current constraints.
NOTE: this will return the string 'constraint not defined' if
the power domain has no max microamps constraint defined by
@@ -185,7 +192,7 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
requested_microamps. This holds the total requested load
current in microamps for this regulator from all its consumer
devices.
@@ -204,125 +211,102 @@ Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_mem_microvolts. This holds the regulator output
voltage setting for this domain measured in microvolts when
the system is suspended to memory.
NOTE: this will return the string 'not defined' if
the power domain has no suspend to memory voltage defined by
platform code.
the system is suspended to memory, for voltage regulators
implementing suspend voltage configuration constraints.
What: /sys/class/regulator/.../suspend_disk_microvolts
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_disk_microvolts. This holds the regulator output
voltage setting for this domain measured in microvolts when
the system is suspended to disk.
NOTE: this will return the string 'not defined' if
the power domain has no suspend to disk voltage defined by
platform code.
the system is suspended to disk, for voltage regulators
implementing suspend voltage configuration constraints.
What: /sys/class/regulator/.../suspend_standby_microvolts
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_standby_microvolts. This holds the regulator output
voltage setting for this domain measured in microvolts when
the system is suspended to standby.
NOTE: this will return the string 'not defined' if
the power domain has no suspend to standby voltage defined by
platform code.
the system is suspended to standby, for voltage regulators
implementing suspend voltage configuration constraints.
What: /sys/class/regulator/.../suspend_mem_mode
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_mem_mode. This holds the regulator operating mode
setting for this domain when the system is suspended to
memory.
NOTE: this will return the string 'not defined' if
the power domain has no suspend to memory mode defined by
platform code.
memory, for regulators implementing suspend mode
configuration constraints.
What: /sys/class/regulator/.../suspend_disk_mode
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_disk_mode. This holds the regulator operating mode
setting for this domain when the system is suspended to disk.
NOTE: this will return the string 'not defined' if
the power domain has no suspend to disk mode defined by
platform code.
setting for this domain when the system is suspended to disk,
for regulators implementing suspend mode configuration
constraints.
What: /sys/class/regulator/.../suspend_standby_mode
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_standby_mode. This holds the regulator operating mode
setting for this domain when the system is suspended to
standby.
NOTE: this will return the string 'not defined' if
the power domain has no suspend to standby mode defined by
platform code.
standby, for regulators implementing suspend mode
configuration constraints.
What: /sys/class/regulator/.../suspend_mem_state
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_mem_state. This holds the regulator operating state
when suspended to memory.
when suspended to memory, for regulators implementing suspend
configuration constraints.
This will be one of the following strings:
'enabled'
'disabled'
'not defined'
This will be one of the same strings reported by
the "state" attribute.
What: /sys/class/regulator/.../suspend_disk_state
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_disk_state. This holds the regulator operating state
when suspended to disk.
when suspended to disk, for regulators implementing
suspend configuration constraints.
This will be one of the following strings:
'enabled'
'disabled'
'not defined'
This will be one of the same strings reported by
the "state" attribute.
What: /sys/class/regulator/.../suspend_standby_state
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_standby_state. This holds the regulator operating
state when suspended to standby.
state when suspended to standby, for regulators implementing
suspend configuration constraints.
This will be one of the following strings:
'enabled'
'disabled'
'not defined'
This will be one of the same strings reported by
the "state" attribute.

14
Documentation/ABI/testing/sysfs-class-uwb_rc
View File

@@ -32,14 +32,16 @@ Contact: linux-usb@vger.kernel.org
Description:
Write:
<channel> [<bpst offset>]
<channel>
to start beaconing on a specific channel, or stop
beaconing if <channel> is -1. Valid channels depends
on the radio controller's supported band groups.
to force a specific channel to be used when beaconing,
or, if <channel> is -1, to prohibit beaconing. If
<channel> is 0, then the default channel selection
algorithm will be used. Valid channels depends on the
radio controller's supported band groups.
<bpst offset> may be used to try and join a specific
beacon group if more than one was found during a scan.
Reading returns the currently active channel, or -1 if
the radio controller is not beaconing.
What: /sys/class/uwb_rc/uwbN/scan
Date: July 2008

53
Documentation/ABI/testing/sysfs-devices-memory
View File

@@ -6,7 +6,6 @@ Description:
internal state of the kernel memory blocks. Files could be
added or removed dynamically to represent hot-add/remove
operations.
Users: hotplug memory add/remove tools
https://w3.opensource.ibm.com/projects/powerpc-utils/
@@ -19,6 +18,56 @@ Description:
This is useful for a user-level agent to determine
identify removable sections of the memory before attempting
potentially expensive hot-remove memory operation
Users: hotplug memory remove tools
https://w3.opensource.ibm.com/projects/powerpc-utils/
What: /sys/devices/system/memory/memoryX/phys_device
Date: September 2008
Contact: Badari Pulavarty <pbadari@us.ibm.com>
Description:
The file /sys/devices/system/memory/memoryX/phys_device
is read-only and is designed to show the name of physical
memory device. Implementation is currently incomplete.
What: /sys/devices/system/memory/memoryX/phys_index
Date: September 2008
Contact: Badari Pulavarty <pbadari@us.ibm.com>
Description:
The file /sys/devices/system/memory/memoryX/phys_index
is read-only and contains the section ID in hexadecimal
which is equivalent to decimal X contained in the
memory section directory name.
What: /sys/devices/system/memory/memoryX/state
Date: September 2008
Contact: Badari Pulavarty <pbadari@us.ibm.com>
Description:
The file /sys/devices/system/memory/memoryX/state
is read-write. When read, it's contents show the
online/offline state of the memory section. When written,
root can toggle the the online/offline state of a removable
memory section (see removable file description above)
using the following commands.
# echo online > /sys/devices/system/memory/memoryX/state
# echo offline > /sys/devices/system/memory/memoryX/state
For example, if /sys/devices/system/memory/memory22/removable
contains a value of 1 and
/sys/devices/system/memory/memory22/state contains the
string "online" the following command can be executed by
by root to offline that section.
# echo offline > /sys/devices/system/memory/memory22/state
Users: hotplug memory remove tools
https://w3.opensource.ibm.com/projects/powerpc-utils/
What: /sys/devices/system/node/nodeX/memoryY
Date: September 2008
Contact: Gary Hade <garyhade@us.ibm.com>
Description:
When CONFIG_NUMA is enabled
/sys/devices/system/node/nodeX/memoryY is a symbolic link that
points to the corresponding /sys/devices/system/memory/memoryY
memory section directory. For example, the following symbolic
link is created for memory section 9 on node0.
/sys/devices/system/node/node0/memory9 -> ../../memory/memory9

4
Documentation/Changes
View File

@@ -33,10 +33,12 @@ o Gnu make 3.79.1 # make --version
o binutils 2.12 # ld -v
o util-linux 2.10o # fdformat --version
o module-init-tools 0.9.10 # depmod -V
o e2fsprogs 1.29 # tune2fs
o e2fsprogs 1.41.4 # e2fsck -V
o jfsutils 1.1.3 # fsck.jfs -V
o reiserfsprogs 3.6.3 # reiserfsck -V 2>&1|grep reiserfsprogs
o xfsprogs 2.6.0 # xfs_db -V
o squashfs-tools 4.0 # mksquashfs -version
o btrfs-progs 0.18 # btrfsck
o pcmciautils 004 # pccardctl -V
o quota-tools 3.09 # quota -V
o PPP 2.4.0 # pppd --version

18
Documentation/CodingStyle
View File

@@ -483,17 +483,25 @@ values. To do the latter, you can stick the following in your .emacs file:
(* (max steps 1)
c-basic-offset)))
(add-hook 'c-mode-common-hook
(lambda ()
;; Add kernel style
(c-add-style
"linux-tabs-only"
'("linux" (c-offsets-alist
(arglist-cont-nonempty
c-lineup-gcc-asm-reg
c-lineup-arglist-tabs-only))))))
(add-hook 'c-mode-hook
(lambda ()
(let ((filename (buffer-file-name)))
;; Enable kernel mode for the appropriate files
(when (and filename
(string-match "~/src/linux-trees" filename))
(string-match (expand-file-name "~/src/linux-trees")
filename))
(setq indent-tabs-mode t)
(c-set-style "linux")
(c-set-offset 'arglist-cont-nonempty
'(c-lineup-gcc-asm-reg
c-lineup-arglist-tabs-only))))))
(c-set-style "linux-tabs-only")))))
This will make emacs go better with the kernel coding style for C
files below ~/src/linux-trees.

11
Documentation/DMA-API.txt
View File

@@ -5,7 +5,7 @@
This document describes the DMA API. For a more gentle introduction
phrased in terms of the pci_ equivalents (and actual examples) see
DMA-mapping.txt
Documentation/PCI/PCI-DMA-mapping.txt.
This API is split into two pieces. Part I describes the API and the
corresponding pci_ API. Part II describes the extensions to the API
@@ -170,16 +170,15 @@ Returns: 0 if successful and a negative error if not.
u64
dma_get_required_mask(struct device *dev)
After setting the mask with dma_set_mask(), this API returns the
actual mask (within that already set) that the platform actually
requires to operate efficiently. Usually this means the returned mask
This API returns the mask that the platform requires to
operate efficiently. Usually this means the returned mask
is the minimum required to cover all of memory. Examining the
required mask gives drivers with variable descriptor sizes the
opportunity to use smaller descriptors as necessary.
Requesting the required mask does not alter the current mask. If you
wish to take advantage of it, you should issue another dma_set_mask()
call to lower the mask again.
wish to take advantage of it, you should issue a dma_set_mask()
call to set the mask to the value returned.
Part Id - Streaming DMA mappings

2
Documentation/DMA-mapping.txt
View File

@@ -26,7 +26,7 @@ mapped only for the time they are actually used and unmapped after the DMA
transfer.
The following API will work of course even on platforms where no such
hardware exists, see e.g. include/asm-i386/pci.h for how it is implemented on
hardware exists, see e.g. arch/x86/include/asm/pci.h for how it is implemented on
top of the virt_to_bus interface.
First of all, you should make sure

2
Documentation/DocBook/Makefile
View File

@@ -12,7 +12,7 @@ DOCBOOKS := z8530book.xml mcabook.xml \
kernel-api.xml filesystems.xml lsm.xml usb.xml kgdb.xml \
gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \
mac80211.xml debugobjects.xml sh.xml
mac80211.xml debugobjects.xml sh.xml regulator.xml
###
# The build process is as follows (targets):

8
Documentation/DocBook/networking.tmpl
View File

@@ -74,6 +74,14 @@
!Enet/sunrpc/rpcb_clnt.c
!Enet/sunrpc/clnt.c
</sect1>
<sect1><title>WiMAX</title>
!Enet/wimax/op-msg.c
!Enet/wimax/op-reset.c
!Enet/wimax/op-rfkill.c
!Enet/wimax/stack.c
!Iinclude/net/wimax.h
!Iinclude/linux/wimax.h
</sect1>
</chapter>
<chapter id="netdev">

304
Documentation/DocBook/regulator.tmpl Normal file
View File

@@ -0,0 +1,304 @@
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
<book id="regulator-api">
<bookinfo>
<title>Voltage and current regulator API</title>
<authorgroup>
<author>
<firstname>Liam</firstname>
<surname>Girdwood</surname>
<affiliation>
<address>
<email>lrg@slimlogic.co.uk</email>
</address>
</affiliation>
</author>
<author>
<firstname>Mark</firstname>
<surname>Brown</surname>
<affiliation>
<orgname>Wolfson Microelectronics</orgname>
<address>
<email>broonie@opensource.wolfsonmicro.com</email>
</address>
</affiliation>
</author>
</authorgroup>
<copyright>
<year>2007-2008</year>
<holder>Wolfson Microelectronics</holder>
</copyright>
<copyright>
<year>2008</year>
<holder>Liam Girdwood</holder>
</copyright>
<legalnotice>
<para>
This documentation is free software; you can redistribute
it and/or modify it under the terms of the GNU General Public
License version 2 as published by the Free Software Foundation.
</para>
<para>
This program is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
</para>
<para>
You should have received a copy of the GNU General Public
License along with this program; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
MA 02111-1307 USA
</para>
<para>
For more details see the file COPYING in the source
distribution of Linux.
</para>
</legalnotice>
</bookinfo>
<toc></toc>
<chapter id="intro">
<title>Introduction</title>
<para>
This framework is designed to provide a standard kernel
interface to control voltage and current regulators.
</para>
<para>
The intention is to allow systems to dynamically control
regulator power output in order to save power and prolong
battery life. This applies to both voltage regulators (where
voltage output is controllable) and current sinks (where current
limit is controllable).
</para>
<para>
Note that additional (and currently more complete) documentation
is available in the Linux kernel source under
<filename>Documentation/power/regulator</filename>.
</para>
<sect1 id="glossary">
<title>Glossary</title>
<para>
The regulator API uses a number of terms which may not be
familiar:
</para>
<glossary>
<glossentry>
<glossterm>Regulator</glossterm>
<glossdef>
<para>
Electronic device that supplies power to other devices. Most
regulators can enable and disable their output and some can also
control their output voltage or current.
</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Consumer</glossterm>
<glossdef>
<para>
Electronic device which consumes power provided by a regulator.
These may either be static, requiring only a fixed supply, or
dynamic, requiring active management of the regulator at
runtime.
</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Power Domain</glossterm>
<glossdef>
<para>
The electronic circuit supplied by a given regulator, including
the regulator and all consumer devices. The configuration of
the regulator is shared between all the components in the
circuit.
</para>
</glossdef>
</glossentry>
<glossentry>
<glossterm>Power Management Integrated Circuit</glossterm>
<acronym>PMIC</acronym>
<glossdef>
<para>
An IC which contains numerous regulators and often also other
subsystems. In an embedded system the primary PMIC is often
equivalent to a combination of the PSU and southbridge in a
desktop system.
</para>
</glossdef>
</glossentry>
</glossary>
</sect1>
</chapter>
<chapter id="consumer">
<title>Consumer driver interface</title>
<para>
This offers a similar API to the kernel clock framework.
Consumer drivers use <link
linkend='API-regulator-get'>get</link> and <link
linkend='API-regulator-put'>put</link> operations to acquire and
release regulators. Functions are
provided to <link linkend='API-regulator-enable'>enable</link>
and <link linkend='API-regulator-disable'>disable</link> the
reguator and to get and set the runtime parameters of the
regulator.
</para>
<para>
When requesting regulators consumers use symbolic names for their
supplies, such as "Vcc", which are mapped into actual regulator
devices by the machine interface.
</para>
<para>
A stub version of this API is provided when the regulator
framework is not in use in order to minimise the need to use
ifdefs.
</para>
<sect1 id="consumer-enable">
<title>Enabling and disabling</title>
<para>
The regulator API provides reference counted enabling and
disabling of regulators. Consumer devices use the <function><link
linkend='API-regulator-enable'>regulator_enable</link></function>
and <function><link
linkend='API-regulator-disable'>regulator_disable</link>
</function> functions to enable and disable regulators. Calls
to the two functions must be balanced.
</para>
<para>
Note that since multiple consumers may be using a regulator and
machine constraints may not allow the regulator to be disabled
there is no guarantee that calling
<function>regulator_disable</function> will actually cause the
supply provided by the regulator to be disabled. Consumer
drivers should assume that the regulator may be enabled at all
times.
</para>
</sect1>
<sect1 id="consumer-config">
<title>Configuration</title>
<para>
Some consumer devices may need to be able to dynamically
configure their supplies. For example, MMC drivers may need to
select the correct operating voltage for their cards. This may
be done while the regulator is enabled or disabled.
</para>
<para>
The <function><link
linkend='API-regulator-set-voltage'>regulator_set_voltage</link>
</function> and <function><link
linkend='API-regulator-set-current-limit'
>regulator_set_current_limit</link>
</function> functions provide the primary interface for this.
Both take ranges of voltages and currents, supporting drivers
that do not require a specific value (eg, CPU frequency scaling
normally permits the CPU to use a wider range of supply
voltages at lower frequencies but does not require that the
supply voltage be lowered). Where an exact value is required
both minimum and maximum values should be identical.
</para>
</sect1>
<sect1 id="consumer-callback">
<title>Callbacks</title>
<para>
Callbacks may also be <link
linkend='API-regulator-register-notifier'>registered</link>
for events such as regulation failures.
</para>
</sect1>
</chapter>
<chapter id="driver">
<title>Regulator driver interface</title>
<para>
Drivers for regulator chips <link
linkend='API-regulator-register'>register</link> the regulators
with the regulator core, providing operations structures to the
core. A <link
linkend='API-regulator-notifier-call-chain'>notifier</link> interface
allows error conditions to be reported to the core.
</para>
<para>
Registration should be triggered by explicit setup done by the
platform, supplying a <link
linkend='API-struct-regulator-init-data'>struct
regulator_init_data</link> for the regulator containing
<link linkend='machine-constraint'>constraint</link> and
<link linkend='machine-supply'>supply</link> information.
</para>
</chapter>
<chapter id="machine">
<title>Machine interface</title>
<para>
This interface provides a way to define how regulators are
connected to consumers on a given system and what the valid
operating parameters are for the system.
</para>
<sect1 id="machine-supply">
<title>Supplies</title>
<para>
Regulator supplies are specified using <link
linkend='API-struct-regulator-consumer-supply'>struct
regulator_consumer_supply</link>. This is done at
<link linkend='driver'>driver registration
time</link> as part of the machine constraints.
</para>
</sect1>
<sect1 id="machine-constraint">
<title>Constraints</title>
<para>
As well as definining the connections the machine interface
also provides constraints definining the operations that
clients are allowed to perform and the parameters that may be
set. This is required since generally regulator devices will
offer more flexibility than it is safe to use on a given
system, for example supporting higher supply voltages than the
consumers are rated for.
</para>
<para>
This is done at <link linkend='driver'>driver
registration time</link> by providing a <link
linkend='API-struct-regulation-constraints'>struct
regulation_constraints</link>.
</para>
<para>
The constraints may also specify an initial configuration for the
regulator in the constraints, which is particularly useful for
use with static consumers.
</para>
</sect1>
</chapter>
<chapter id="api">
<title>API reference</title>
<para>
Due to limitations of the kernel documentation framework and the
existing layout of the source code the entire regulator API is
documented here.
</para>
!Iinclude/linux/regulator/consumer.h
!Iinclude/linux/regulator/machine.h
!Iinclude/linux/regulator/driver.h
!Edrivers/regulator/core.c
</chapter>
</book>

189
Documentation/DocBook/uio-howto.tmpl
View File

@@ -41,6 +41,18 @@ GPL version 2.
</abstract>
<revhistory>
<revision>
<revnumber>0.7</revnumber>
<date>2008-12-23</date>
<authorinitials>hjk</authorinitials>
<revremark>Added generic platform drivers and offset attribute.</revremark>
</revision>
<revision>
<revnumber>0.6</revnumber>
<date>2008-12-05</date>
<authorinitials>hjk</authorinitials>
<revremark>Added description of portio sysfs attributes.</revremark>
</revision>
<revision>
<revnumber>0.5</revnumber>
<date>2008-05-22</date>
@@ -306,6 +318,16 @@ interested in translating it, please email me
pointed to by addr.
</para>
</listitem>
<listitem>
<para>
<filename>offset</filename>: The offset, in bytes, that has to be
added to the pointer returned by <function>mmap()</function> to get
to the actual device memory. This is important if the device's memory
is not page aligned. Remember that pointers returned by
<function>mmap()</function> are always page aligned, so it is good
style to always add this offset.
</para>
</listitem>
</itemizedlist>
<para>
@@ -318,6 +340,54 @@ interested in translating it, please email me
offset = N * getpagesize();
</programlisting>
<para>
Sometimes there is hardware with memory-like regions that can not be
mapped with the technique described here, but there are still ways to
access them from userspace. The most common example are x86 ioports.
On x86 systems, userspace can access these ioports using
<function>ioperm()</function>, <function>iopl()</function>,
<function>inb()</function>, <function>outb()</function>, and similar
functions.
</para>
<para>
Since these ioport regions can not be mapped, they will not appear under
<filename>/sys/class/uio/uioX/maps/</filename> like the normal memory
described above. Without information about the port regions a hardware
has to offer, it becomes difficult for the userspace part of the
driver to find out which ports belong to which UIO device.
</para>
<para>
To address this situation, the new directory
<filename>/sys/class/uio/uioX/portio/</filename> was added. It only
exists if the driver wants to pass information about one or more port
regions to userspace. If that is the case, subdirectories named
<filename>port0</filename>, <filename>port1</filename>, and so on,
will appear underneath
<filename>/sys/class/uio/uioX/portio/</filename>.
</para>
<para>
Each <filename>portX/</filename> directory contains three read-only
files that show start, size, and type of the port region:
</para>
<itemizedlist>
<listitem>
<para>
<filename>start</filename>: The first port of this region.
</para>
</listitem>
<listitem>
<para>
<filename>size</filename>: The number of ports in this region.
</para>
</listitem>
<listitem>
<para>
<filename>porttype</filename>: A string describing the type of port.
</para>
</listitem>
</itemizedlist>
</sect1>
</chapter>
@@ -339,12 +409,12 @@ offset = N * getpagesize();
<itemizedlist>
<listitem><para>
<varname>char *name</varname>: Required. The name of your driver as
<varname>const char *name</varname>: Required. The name of your driver as
it will appear in sysfs. I recommend using the name of your module for this.
</para></listitem>
<listitem><para>
<varname>char *version</varname>: Required. This string appears in
<varname>const char *version</varname>: Required. This string appears in
<filename>/sys/class/uio/uioX/version</filename>.
</para></listitem>
@@ -355,6 +425,13 @@ mapping you need to fill one of the <varname>uio_mem</varname> structures.
See the description below for details.
</para></listitem>
<listitem><para>
<varname>struct uio_port port[ MAX_UIO_PORTS_REGIONS ]</varname>: Required
if you want to pass information about ioports to userspace. For each port
region you need to fill one of the <varname>uio_port</varname> structures.
See the description below for details.
</para></listitem>
<listitem><para>
<varname>long irq</varname>: Required. If your hardware generates an
interrupt, it's your modules task to determine the irq number during
@@ -448,6 +525,42 @@ Please do not touch the <varname>kobj</varname> element of
<varname>struct uio_mem</varname>! It is used by the UIO framework
to set up sysfs files for this mapping. Simply leave it alone.
</para>
<para>
Sometimes, your device can have one or more port regions which can not be
mapped to userspace. But if there are other possibilities for userspace to
access these ports, it makes sense to make information about the ports
available in sysfs. For each region, you have to set up a
<varname>struct uio_port</varname> in the <varname>port[]</varname> array.
Here's a description of the fields of <varname>struct uio_port</varname>:
</para>
<itemizedlist>
<listitem><para>
<varname>char *porttype</varname>: Required. Set this to one of the predefined
constants. Use <varname>UIO_PORT_X86</varname> for the ioports found in x86
architectures.
</para></listitem>
<listitem><para>
<varname>unsigned long start</varname>: Required if the port region is used.
Fill in the number of the first port of this region.
</para></listitem>
<listitem><para>
<varname>unsigned long size</varname>: Fill in the number of ports in this
region. If <varname>size</varname> is zero, the region is considered unused.
Note that you <emphasis>must</emphasis> initialize <varname>size</varname>
with zero for all unused regions.
</para></listitem>
</itemizedlist>
<para>
Please do not touch the <varname>portio</varname> element of
<varname>struct uio_port</varname>! It is used internally by the UIO
framework to set up sysfs files for this region. Simply leave it alone.
</para>
</sect1>
<sect1 id="adding_irq_handler">
@@ -497,6 +610,78 @@ to set up sysfs files for this mapping. Simply leave it alone.
</para>
</sect1>
<sect1 id="using_uio_pdrv">
<title>Using uio_pdrv for platform devices</title>
<para>
In many cases, UIO drivers for platform devices can be handled in a
generic way. In the same place where you define your
<varname>struct platform_device</varname>, you simply also implement
your interrupt handler and fill your
<varname>struct uio_info</varname>. A pointer to this
<varname>struct uio_info</varname> is then used as
<varname>platform_data</varname> for your platform device.
</para>
<para>
You also need to set up an array of <varname>struct resource</varname>
containing addresses and sizes of your memory mappings. This
information is passed to the driver using the
<varname>.resource</varname> and <varname>.num_resources</varname>
elements of <varname>struct platform_device</varname>.
</para>
<para>
You now have to set the <varname>.name</varname> element of
<varname>struct platform_device</varname> to
<varname>"uio_pdrv"</varname> to use the generic UIO platform device
driver. This driver will fill the <varname>mem[]</varname> array
according to the resources given, and register the device.
</para>
<para>
The advantage of this approach is that you only have to edit a file
you need to edit anyway. You do not have to create an extra driver.
</para>
</sect1>
<sect1 id="using_uio_pdrv_genirq">
<title>Using uio_pdrv_genirq for platform devices</title>
<para>
Especially in embedded devices, you frequently find chips where the
irq pin is tied to its own dedicated interrupt line. In such cases,
where you can be really sure the interrupt is not shared, we can take
the concept of <varname>uio_pdrv</varname> one step further and use a
generic interrupt handler. That's what
<varname>uio_pdrv_genirq</varname> does.
</para>
<para>
The setup for this driver is the same as described above for
<varname>uio_pdrv</varname>, except that you do not implement an
interrupt handler. The <varname>.handler</varname> element of
<varname>struct uio_info</varname> must remain
<varname>NULL</varname>. The <varname>.irq_flags</varname> element
must not contain <varname>IRQF_SHARED</varname>.
</para>
<para>
You will set the <varname>.name</varname> element of
<varname>struct platform_device</varname> to
<varname>"uio_pdrv_genirq"</varname> to use this driver.
</para>
<para>
The generic interrupt handler of <varname>uio_pdrv_genirq</varname>
will simply disable the interrupt line using
<function>disable_irq_nosync()</function>. After doing its work,
userspace can reenable the interrupt by writing 0x00000001 to the UIO
device file. The driver already implements an
<function>irq_control()</function> to make this possible, you must not
implement your own.
</para>
<para>
Using <varname>uio_pdrv_genirq</varname> not only saves a few lines of
interrupt handler code. You also do not need to know anything about
the chip's internal registers to create the kernel part of the driver.
All you need to know is the irq number of the pin the chip is
connected to.
</para>
</sect1>
</chapter>
<chapter id="userspace_driver" xreflabel="Writing a driver in user space">

4
Documentation/IO-mapping.txt
View File

@@ -1,6 +1,6 @@
[ NOTE: The virt_to_bus() and bus_to_virt() functions have been
superseded by the functionality provided by the PCI DMA
interface (see Documentation/DMA-mapping.txt). They continue
superseded by the functionality provided by the PCI DMA interface
(see Documentation/PCI/PCI-DMA-mapping.txt). They continue
to be documented below for historical purposes, but new code
must not use them. --davidm 00/12/12 ]

3
Documentation/PCI/pci.txt
View File

@@ -294,7 +294,8 @@ NOTE: pci_enable_device() can fail! Check the return value.
pci_set_master() will enable DMA by setting the bus master bit
in the PCI_COMMAND register. It also fixes the latency timer value if
it's set to something bogus by the BIOS.
it's set to something bogus by the BIOS. pci_clear_master() will
disable DMA by clearing the bus master bit.
If the PCI device can use the PCI Memory-Write-Invalidate transaction,
call pci_set_mwi(). This enables the PCI_COMMAND bit for Mem-Wr-Inval

2
Documentation/RCU/00-INDEX
View File

@@ -12,6 +12,8 @@ rcuref.txt
- Reference-count design for elements of lists/arrays protected by RCU
rcu.txt
- RCU Concepts
rcubarrier.txt
- Unloading modules that use RCU callbacks
RTFP.txt
- List of RCU papers (bibliography) going back to 1980.
torture.txt

304
Documentation/RCU/rcubarrier.txt Normal file
View File

@@ -0,0 +1,304 @@
RCU and Unloadable Modules
[Originally published in LWN Jan. 14, 2007: http://lwn.net/Articles/217484/]
RCU (read-copy update) is a synchronization mechanism that can be thought
of as a replacement for read-writer locking (among other things), but with
very low-overhead readers that are immune to deadlock, priority inversion,
and unbounded latency. RCU read-side critical sections are delimited
by rcu_read_lock() and rcu_read_unlock(), which, in non-CONFIG_PREEMPT
kernels, generate no code whatsoever.
This means that RCU writers are unaware of the presence of concurrent
readers, so that RCU updates to shared data must be undertaken quite
carefully, leaving an old version of the data structure in place until all
pre-existing readers have finished. These old versions are needed because
such readers might hold a reference to them. RCU updates can therefore be
rather expensive, and RCU is thus best suited for read-mostly situations.
How can an RCU writer possibly determine when all readers are finished,
given that readers might well leave absolutely no trace of their
presence? There is a synchronize_rcu() primitive that blocks until all
pre-existing readers have completed. An updater wishing to delete an
element p from a linked list might do the following, while holding an
appropriate lock, of course:
list_del_rcu(p);
synchronize_rcu();
kfree(p);
But the above code cannot be used in IRQ context -- the call_rcu()
primitive must be used instead. This primitive takes a pointer to an
rcu_head struct placed within the RCU-protected data structure and
another pointer to a function that may be invoked later to free that
structure. Code to delete an element p from the linked list from IRQ
context might then be as follows:
list_del_rcu(p);
call_rcu(&p->rcu, p_callback);
Since call_rcu() never blocks, this code can safely be used from within
IRQ context. The function p_callback() might be defined as follows:
static void p_callback(struct rcu_head *rp)
{
struct pstruct *p = container_of(rp, struct pstruct, rcu);
kfree(p);
}
Unloading Modules That Use call_rcu()
But what if p_callback is defined in an unloadable module?
If we unload the module while some RCU callbacks are pending,
the CPUs executing these callbacks are going to be severely
disappointed when they are later invoked, as fancifully depicted at
http://lwn.net/images/ns/kernel/rcu-drop.jpg.
We could try placing a synchronize_rcu() in the module-exit code path,
but this is not sufficient. Although synchronize_rcu() does wait for a
grace period to elapse, it does not wait for the callbacks to complete.
One might be tempted to try several back-to-back synchronize_rcu()
calls, but this is still not guaranteed to work. If there is a very
heavy RCU-callback load, then some of the callbacks might be deferred
in order to allow other processing to proceed. Such deferral is required
in realtime kernels in order to avoid excessive scheduling latencies.
rcu_barrier()
We instead need the rcu_barrier() primitive. This primitive is similar
to synchronize_rcu(), but instead of waiting solely for a grace
period to elapse, it also waits for all outstanding RCU callbacks to
complete. Pseudo-code using rcu_barrier() is as follows:
1. Prevent any new RCU callbacks from being posted.
2. Execute rcu_barrier().
3. Allow the module to be unloaded.
Quick Quiz #1: Why is there no srcu_barrier()?
The rcutorture module makes use of rcu_barrier in its exit function
as follows:
1 static void
2 rcu_torture_cleanup(void)
3 {
4 int i;
5
6 fullstop = 1;
7 if (shuffler_task != NULL) {
8 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
9 kthread_stop(shuffler_task);
10 }
11 shuffler_task = NULL;
12
13 if (writer_task != NULL) {
14 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
15 kthread_stop(writer_task);
16 }
17 writer_task = NULL;
18
19 if (reader_tasks != NULL) {
20 for (i = 0; i < nrealreaders; i++) {
21 if (reader_tasks[i] != NULL) {
22 VERBOSE_PRINTK_STRING(
23 "Stopping rcu_torture_reader task");
24 kthread_stop(reader_tasks[i]);
25 }
26 reader_tasks[i] = NULL;
27 }
28 kfree(reader_tasks);
29 reader_tasks = NULL;
30 }
31 rcu_torture_current = NULL;
32
33 if (fakewriter_tasks != NULL) {
34 for (i = 0; i < nfakewriters; i++) {
35 if (fakewriter_tasks[i] != NULL) {
36 VERBOSE_PRINTK_STRING(
37 "Stopping rcu_torture_fakewriter task");
38 kthread_stop(fakewriter_tasks[i]);
39 }
40 fakewriter_tasks[i] = NULL;
41 }
42 kfree(fakewriter_tasks);
43 fakewriter_tasks = NULL;
44 }
45
46 if (stats_task != NULL) {
47 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
48 kthread_stop(stats_task);
49 }
50 stats_task = NULL;
51
52 /* Wait for all RCU callbacks to fire. */
53 rcu_barrier();
54
55 rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
56
57 if (cur_ops->cleanup != NULL)
58 cur_ops->cleanup();
59 if (atomic_read(&n_rcu_torture_error))
60 rcu_torture_print_module_parms("End of test: FAILURE");
61 else
62 rcu_torture_print_module_parms("End of test: SUCCESS");
63 }
Line 6 sets a global variable that prevents any RCU callbacks from
re-posting themselves. This will not be necessary in most cases, since
RCU callbacks rarely include calls to call_rcu(). However, the rcutorture
module is an exception to this rule, and therefore needs to set this
global variable.
Lines 7-50 stop all the kernel tasks associated with the rcutorture
module. Therefore, once execution reaches line 53, no more rcutorture
RCU callbacks will be posted. The rcu_barrier() call on line 53 waits
for any pre-existing callbacks to complete.
Then lines 55-62 print status and do operation-specific cleanup, and
then return, permitting the module-unload operation to be completed.
Quick Quiz #2: Is there any other situation where rcu_barrier() might
be required?
Your module might have additional complications. For example, if your
module invokes call_rcu() from timers, you will need to first cancel all
the timers, and only then invoke rcu_barrier() to wait for any remaining
RCU callbacks to complete.
Implementing rcu_barrier()
Dipankar Sarma's implementation of rcu_barrier() makes use of the fact
that RCU callbacks are never reordered once queued on one of the per-CPU
queues. His implementation queues an RCU callback on each of the per-CPU
callback queues, and then waits until they have all started executing, at
which point, all earlier RCU callbacks are guaranteed to have completed.
The original code for rcu_barrier() was as follows:
1 void rcu_barrier(void)
2 {
3 BUG_ON(in_interrupt());
4 /* Take cpucontrol mutex to protect against CPU hotplug */
5 mutex_lock(&rcu_barrier_mutex);
6 init_completion(&rcu_barrier_completion);
7 atomic_set(&rcu_barrier_cpu_count, 0);
8 on_each_cpu(rcu_barrier_func, NULL, 0, 1);
9 wait_for_completion(&rcu_barrier_completion);
10 mutex_unlock(&rcu_barrier_mutex);
11 }
Line 3 verifies that the caller is in process context, and lines 5 and 10
use rcu_barrier_mutex to ensure that only one rcu_barrier() is using the
global completion and counters at a time, which are initialized on lines
6 and 7. Line 8 causes each CPU to invoke rcu_barrier_func(), which is
shown below. Note that the final "1" in on_each_cpu()'s argument list
ensures that all the calls to rcu_barrier_func() will have completed
before on_each_cpu() returns. Line 9 then waits for the completion.
This code was rewritten in 2008 to support rcu_barrier_bh() and
rcu_barrier_sched() in addition to the original rcu_barrier().
The rcu_barrier_func() runs on each CPU, where it invokes call_rcu()
to post an RCU callback, as follows:
1 static void rcu_barrier_func(void *notused)
2 {
3 int cpu = smp_processor_id();
4 struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
5 struct rcu_head *head;
6
7 head = &rdp->barrier;
8 atomic_inc(&rcu_barrier_cpu_count);
9 call_rcu(head, rcu_barrier_callback);
10 }
Lines 3 and 4 locate RCU's internal per-CPU rcu_data structure,
which contains the struct rcu_head that needed for the later call to
call_rcu(). Line 7 picks up a pointer to this struct rcu_head, and line
8 increments a global counter. This counter will later be decremented
by the callback. Line 9 then registers the rcu_barrier_callback() on
the current CPU's queue.
The rcu_barrier_callback() function simply atomically decrements the
rcu_barrier_cpu_count variable and finalizes the completion when it
reaches zero, as follows:
1 static void rcu_barrier_callback(struct rcu_head *notused)
2 {
3 if (atomic_dec_and_test(&rcu_barrier_cpu_count))
4 complete(&rcu_barrier_completion);
5 }
Quick Quiz #3: What happens if CPU 0's rcu_barrier_func() executes
immediately (thus incrementing rcu_barrier_cpu_count to the
value one), but the other CPU's rcu_barrier_func() invocations
are delayed for a full grace period? Couldn't this result in
rcu_barrier() returning prematurely?
rcu_barrier() Summary
The rcu_barrier() primitive has seen relatively little use, since most
code using RCU is in the core kernel rather than in modules. However, if
you are using RCU from an unloadable module, you need to use rcu_barrier()
so that your module may be safely unloaded.
Answers to Quick Quizzes
Quick Quiz #1: Why is there no srcu_barrier()?
Answer: Since there is no call_srcu(), there can be no outstanding SRCU
callbacks. Therefore, there is no need to wait for them.
Quick Quiz #2: Is there any other situation where rcu_barrier() might
be required?
Answer: Interestingly enough, rcu_barrier() was not originally
implemented for module unloading. Nikita Danilov was using
RCU in a filesystem, which resulted in a similar situation at
filesystem-unmount time. Dipankar Sarma coded up rcu_barrier()
in response, so that Nikita could invoke it during the
filesystem-unmount process.
Much later, yours truly hit the RCU module-unload problem when
implementing rcutorture, and found that rcu_barrier() solves
this problem as well.
Quick Quiz #3: What happens if CPU 0's rcu_barrier_func() executes
immediately (thus incrementing rcu_barrier_cpu_count to the
value one), but the other CPU's rcu_barrier_func() invocations
are delayed for a full grace period? Couldn't this result in
rcu_barrier() returning prematurely?
Answer: This cannot happen. The reason is that on_each_cpu() has its last
argument, the wait flag, set to "1". This flag is passed through
to smp_call_function() and further to smp_call_function_on_cpu(),
causing this latter to spin until the cross-CPU invocation of
rcu_barrier_func() has completed. This by itself would prevent
a grace period from completing on non-CONFIG_PREEMPT kernels,
since each CPU must undergo a context switch (or other quiescent
state) before the grace period can complete. However, this is
of no use in CONFIG_PREEMPT kernels.
Therefore, on_each_cpu() disables preemption across its call
to smp_call_function() and also across the local call to
rcu_barrier_func(). This prevents the local CPU from context
switching, again preventing grace periods from completing. This
means that all CPUs have executed rcu_barrier_func() before
the first rcu_barrier_callback() can possibly execute, in turn
preventing rcu_barrier_cpu_count from prematurely reaching zero.
Currently, -rt implementations of RCU keep but a single global
queue for RCU callbacks, and thus do not suffer from this
problem. However, when the -rt RCU eventually does have per-CPU
callback queues, things will have to change. One simple change
is to add an rcu_read_lock() before line 8 of rcu_barrier()
and an rcu_read_unlock() after line 8 of this same function. If
you can think of a better change, please let me know!

4
Documentation/accounting/getdelays.c
View File

@@ -392,6 +392,10 @@ int main(int argc, char *argv[])
goto err;
}
}
if (!maskset && !tid && !containerset) {
usage();
goto err;
}
do {
int i;

45
Documentation/bad_memory.txt Normal file
View File

@@ -0,0 +1,45 @@
March 2008
Jan-Simon Moeller, dl9pf@gmx.de
How to deal with bad memory e.g. reported by memtest86+ ?
#########################################################
There are three possibilities I know of:
1) Reinsert/swap the memory modules
2) Buy new modules (best!) or try to exchange the memory
if you have spare-parts
3) Use BadRAM or memmap
This Howto is about number 3) .
BadRAM
######
BadRAM is the actively developed and available as kernel-patch
here: http://rick.vanrein.org/linux/badram/
For more details see the BadRAM documentation.
memmap
######
memmap is already in the kernel and usable as kernel-parameter at
boot-time. Its syntax is slightly strange and you may need to
calculate the values by yourself!
Syntax to exclude a memory area (see kernel-parameters.txt for details):
memmap=<size>$<address>
Example: memtest86+ reported here errors at address 0x18691458, 0x18698424 and
some others. All had 0x1869xxxx in common, so I chose a pattern of
0x18690000,0xffff0000.
With the numbers of the example above:
memmap=64K$0x18690000
or
memmap=0x10000$0x18690000

3
Documentation/blackfin/00-INDEX
View File

@@ -9,3 +9,6 @@ cachefeatures.txt
Filesystems
- Requirements for mounting the root file system.
bfin-gpio-note.txt
- Notes in developing/using bfin-gpio driver.

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