Commit Graph

25548 Commits

Author SHA1 Message Date
Peter Zijlstra
b6a86c746f sched: fix sched_domain aggregation
Keeping the aggregate on the first cpu of the sched domain has two problems:
 - it could collide between different sched domains on different cpus
 - it could slow things down because of the remote accesses

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:32 +02:00
Peter Zijlstra
c09595f63b sched: revert revert of: fair-group: SMP-nice for group scheduling
Try again..

Initial commit: 18d95a2832
Revert: 6363ca57c7

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:29 +02:00
Ingo Molnar
92af4e2902 x86, AMD IOMMU, build fix #2
fix:

 arch/x86/kernel/amd_iommu.c: In function ‘amd_iommu_init_dma_ops':
 arch/x86/kernel/amd_iommu.c:940: error: lvalue required as left operand of assignment
 arch/x86/kernel/amd_iommu.c:941: error: lvalue required as left operand of assignment

due to !CONFIG_GART_IOMMU.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 10:52:34 +02:00
Steven Whitehouse
b2cad26cfc [GFS2] Remove obsolete conversion deadlock avoidance code
This is only used by GFS1 so can be removed.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-06-27 09:39:47 +01:00
Steven Whitehouse
1bdad60633 [GFS2] Remove remote lock dropping code
There are several reasons why this is undesirable:

 1. It never happens during normal operation anyway
 2. If it does happen it causes performance to be very, very poor
 3. It isn't likely to solve the original problem (memory shortage
    on remote DLM node) it was supposed to solve
 4. It uses a bunch of arbitrary constants which are unlikely to be
    correct for any particular situation and for which the tuning seems
    to be a black art.
 5. In an N node cluster, only 1/N of the dropped locked will actually
    contribute to solving the problem on average.

So all in all we are better off without it. This also makes merging
the lock_dlm module into GFS2 a bit easier.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-06-27 09:39:44 +01:00
Joerg Roedel
c6da992e16 x86, AMD IOMMU: add amd_iommu.h to export functions to the generic x86 dma code
This patch adds the amd_iommu.h file which will be included in the generic
code.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Cc: iommu@lists.linux-foundation.org
Cc: bhavna.sarathy@amd.com
Cc: Sebastian.Biemueller@amd.com
Cc: robert.richter@amd.com
Cc: joro@8bytes.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 10:12:21 +02:00
Joerg Roedel
8d283c35a2 x86, AMD IOMMU: add header file for driver data structures and defines
This patch adds a header file local to the AMD IOMMU driver with constants and
data structures needed in the code.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Cc: iommu@lists.linux-foundation.org
Cc: bhavna.sarathy@amd.com
Cc: Sebastian.Biemueller@amd.com
Cc: robert.richter@amd.com
Cc: joro@8bytes.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 10:12:07 +02:00
Jaroslav Kysela
69776bf3a7 ALSA: Release v1.0.17rc3
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
2008-06-27 10:11:58 +02:00
Assaf Krauss
b662348662 mac80211: 11h - Handling measurement request
This patch handles the 11h measurement request information element.
This is minimal requested implementation - refuse measurement.

Signed-off-by: Assaf Krauss <assaf.krauss@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-06-26 16:49:14 -04:00
Assaf Krauss
f2df38596a mac80211: 11h Infrastructure - Parsing
This patch introduces parsing of 11h and 11d related elements from incoming
management frames.

Signed-off-by: Assaf Krauss <assaf.krauss@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-06-26 16:49:14 -04:00
Hans Verkuil
7fa8e6fa15 V4L/DVB (8092): videodev: simplify and fix standard enumeration
VIDIOC_ENUMSTD did not return all the PAL/SECAM/NTSC variants: it just returned
one single PAL/SECAM/NTSC standard without separate entries for the trickier
standards like NTSC-JP.

Changed the code so that it behaves better.

Also simplified the if/switch statements into a common standards lookup table.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2008-06-26 15:58:57 -03:00
Tim Farrington
6e501a3f4a V4L/DVB (8048): saa7134: Fix entries for Avermedia A16d and Avermedia E506
Also, adds IR table for Avermedia A16d

Signed-off-by: Tim Farrington <timf@iinet.net.au>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2008-06-26 15:58:52 -03:00
Hans Verkuil
45270a1531 V4L/DVB (8007): cx18/cx25840: the S-Video LUMA input can use all In1-In8 inputs
The S-Video LUMA input was restricted to the In1-In4 inputs, but it
turns out that it can use the full range of In1-In8.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2008-06-26 15:58:42 -03:00
Henrique de Moraes Holschuh
5005657cbd rfkill: rename the rfkill_state states and add block-locked state
The current naming of rfkill_state causes a lot of confusion: not only the
"kill" in rfkill suggests negative logic, but also the fact that rfkill cannot
turn anything on (it can just force something off or stop forcing something
off) is often forgotten.

Rename RFKILL_STATE_OFF to RFKILL_STATE_SOFT_BLOCKED (transmitter is blocked
and will not operate; state can be changed by a toggle_radio request), and
RFKILL_STATE_ON to RFKILL_STATE_UNBLOCKED (transmitter is not blocked, and may
operate).

Also, add a new third state, RFKILL_STATE_HARD_BLOCKED (transmitter is blocked
and will not operate; state cannot be changed through a toggle_radio request),
which is used by drivers to indicate a wireless transmiter was blocked by a
hardware rfkill line that accepts no overrides.

Keep the old names as #defines, but document them as deprecated.  This way,
drivers can be converted to the new names *and* verified to actually use rfkill
correctly one by one.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-06-26 14:21:22 -04:00
Henrique de Moraes Holschuh
79399a8d19 rfkill: add notifier chains support
Add a notifier chain for use by the rfkill class.  This notifier chain
signals the following events (more to be added when needed):

  1. rfkill: rfkill device state has changed

A pointer to the rfkill struct will be passed as a parameter.

The notifier message types have been added to include/linux/rfkill.h
instead of to include/linux/notifier.h in order to avoid the madness of
modifying a header used globally (and that triggers an almost full tree
rebuild every time it is touched) with information that is of interest only
to code that includes the rfkill.h header.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-06-26 14:21:21 -04:00
Henrique de Moraes Holschuh
477576a073 rfkill: add the WWAN radio type
Unfortunately, instead of adding a generic Wireless WAN type, a technology-
specific type (WiMAX) was added.  That's useless for other WWAN devices,
such as EDGE, UMTS, X-RTT and other such radios.

Add a WWAN rfkill type for generic wireless WAN devices.  No keys are added
as most devices really want to use KEY_WLAN for WWAN control (in a cycle of
none, WLAN, WWAN, WLAN+WWAN) and need no specific keycode added.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Cc: Iñaky Pérez-González <inaky.perez-gonzalez@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-06-26 14:21:20 -04:00
Henrique de Moraes Holschuh
801e49af4c rfkill: add read-write rfkill switch support
Currently, rfkill support for read/write rfkill switches is hacked through
a round-trip over the input layer and rfkill-input to let a driver sync
rfkill->state to hardware changes.

This is buggy and sub-optimal.  It causes real problems.  It is best to
think of the rfkill class as supporting only write-only switches at the
moment.

In order to implement the read/write functionality properly:

Add a get_state() hook that is called by the class every time it needs to
fetch the current state of the switch.  Add a call to this hook every time
the *current* state of the radio plays a role in a decision.

Also add a force_state() method that can be used to forcefully syncronize
the class' idea of the current state of the switch.  This allows for a
faster implementation of the read/write functionality, as a driver which
get events on switch changes can avoid the need for a get_state() hook.

If the get_state() hook is left as NULL, current behaviour is maintained,
so this change is fully backwards compatible with the current rfkill
drivers.

For hardware that issues events when the rfkill state changes, leave
get_state() NULL in the rfkill struct, set the initial state properly
before registering with the rfkill class, and use the force_state() method
in the driver to keep the rfkill interface up-to-date.

get_state() can be called by the class from atomic context. It must not
sleep.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-06-26 14:21:20 -04:00
Henrique de Moraes Holschuh
f3146aff7f rfkill: clarify meaning of rfkill states
rfkill really should have been named rfswitch.  As it is, one can get
confused whether RFKILL_STATE_ON means the KILL switch is on (and
therefore, the radio is being *blocked* from operating), or whether it
means the RADIO rf output is on.

Clearly state that RFKILL_STATE_ON means the radio is *unblocked* from
operating (i.e. there is no rf killing going on).

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-06-26 14:21:19 -04:00
Max Asbock
41aefdcc98 x86: shift bits the right way in native_read_tscp
native_read_tscp shifts the bits in the high order value in the
wrong direction, the attached patch fixes that.

Signed-off-by: Max Asbock <masbock@linux.vnet.ibm.com>
Acked-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-26 14:49:17 +02:00
Jens Axboe
15c8b6c1aa on_each_cpu(): kill unused 'retry' parameter
It's not even passed on to smp_call_function() anymore, since that
was removed. So kill it.

Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:24:38 +02:00
Jens Axboe
8691e5a8f6 smp_call_function: get rid of the unused nonatomic/retry argument
It's never used and the comments refer to nonatomic and retry
interchangably. So get rid of it.

Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:24:35 +02:00
Jens Axboe
490f5de52a sh: convert to generic helpers for IPI function calls
This converts sh to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single(). Not tested,
but it compiles.

Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:22:58 +02:00
Jens Axboe
dbcf4787d8 parisc: convert to generic helpers for IPI function calls
This converts parisc to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single(). Tested by
Kyle, seems to work.

Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:22:57 +02:00
Jens Axboe
2f304c0a0a mips: convert to generic helpers for IPI function calls
This converts mips to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single(). Not tested,
but it compiles.

mips shares the same IPI for smp_call_function() and
smp_call_function_single(), since not all mips platforms have enough
available IPIs to support seperate setups.

Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:22:57 +02:00
Jens Axboe
7b7426c8a6 m32r: convert to generic helpers for IPI function calls
This converts m32r to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single(). Not tested,
not even compiled.

Cc: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:22:57 +02:00
Jens Axboe
f6dd9fa5a7 arm: convert to generic helpers for IPI function calls
This converts arm to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single().

Fixups and testing done by Catalin Marinas <catalin.marinas@arm.com>

Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:22:57 +02:00
Jens Axboe
c524a1d891 alpha: convert to generic helpers for IPI function calls
This converts alpha to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single().

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:22:57 +02:00
Jens Axboe
f27b433ef3 ia64: convert to generic helpers for IPI function calls
This converts ia64 to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single().

Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:22:30 +02:00
Jens Axboe
b7d7a2404f powerpc: convert to generic helpers for IPI function calls
This converts ppc to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single().

ppc loses the timeout functionality of smp_call_function_mask() with
this change, as the generic code does not provide that.

Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:22:13 +02:00
Jens Axboe
3b16cf8748 x86: convert to generic helpers for IPI function calls
This converts x86, x86-64, and xen to use the new helpers for
smp_call_function() and friends, and adds support for
smp_call_function_single().

Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:21:54 +02:00
Jens Axboe
3d44223327 Add generic helpers for arch IPI function calls
This adds kernel/smp.c which contains helpers for IPI function calls. In
addition to supporting the existing smp_call_function() in a more efficient
manner, it also adds a more scalable variant called smp_call_function_single()
for calling a given function on a single CPU only.

The core of this is based on the x86-64 patch from Nick Piggin, lots of
changes since then. "Alan D. Brunelle" <Alan.Brunelle@hp.com> has
contributed lots of fixes and suggestions as well. Also thanks to
Paul E. McKenney <paulmck@linux.vnet.ibm.com> for reviewing RCU usage
and getting rid of the data allocation fallback deadlock.

Acked-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26 11:21:34 +02:00
Ingo Molnar
9a13150109 Merge commit 'v2.6.26-rc8' into core/rcu 2008-06-26 09:24:23 +02:00
Jarkko Nikula
e2be2ccf94 ALSA: ASoC: Add support for generic DAPM register modifier widget
This generic register modifier widget is for updating multiple codec
register bits at once when the widget changes its power state.

Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
Signed-off-by: Liam Girdwood <lg@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
2008-06-26 09:02:10 +02:00
Jaroslav Kysela
eabe3228a8 [ALSA] Revert "alsa: add annotations to bitwise type snd_pcm_hw_param_t"
This reverts commit 36b34d2437104f323e09d7c6af6451d3c0b9c0cd.

From: Al Viro <viro@ZenIV.linux.org.uk>

WIW, *all* this stuff is not bitwise at all.  For crying out loud, half
of these types are routinely used as array indices and loop variables...

If anything, we want a different set of allowed operations - subtraction
between elements of type (yielding integer), addition/subtraction of
integer types not bigger than ours (yielding our type), comparisons,
assignments (=, +=, -=, passing to function as argument, return from
function, initializers) and second/third arguments in ?:.  With 0 *not*
being allowed as a constant of such type.

It's not bitwise; we may use the same infrastructure in sparse, but it
should be a separate class of types (__attribute__((affine))).

dma_addr_t is another candidate for the same treatment, but there we'll
need helpers for conversions to hw-acceptable form (dma_to_le32(), etc.)
and gradual conversion of drivers.

ALSA ones and pm mess are absolutely straightforward cases, though.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
2008-06-26 08:53:05 +02:00
Anton Vorontsov
d14b3dd619 powerpc/QE: use arch_initcall to probe QUICC Engine GPIOs
It was discussed that global arch_initcall() is preferred way to probe
QE GPIOs, so let's use it.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
2008-06-26 01:49:09 -05:00
Kumar Gala
d3c511ac1d powerpc/cpm: Remove !CONFIG_PPC_CPM_NEW_BINDING code
Now that arch/ppc is gone we always define CONFIG_PPC_CPM_NEW_BINDING so
we can remove all the code associated with !CONFIG_PPC_CPM_NEW_BINDING.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
2008-06-26 01:49:06 -05:00
Kumar Gala
aba11fc50c powerpc/e500mc: flush L2 on NAP for e500mc
If we have an L2CSR register (e500mc) we need to flush the L2 before going
to nap.  We use the HW flush mechanism provided in that register.

The code reuses the CPU_FTR_604_PERF_MON bit as it is no longer used by
any code in the kernel.  Additionally we didn't reuse the exist L2CR
feature bit as this is intended for the 7xxx L2CR register and L2CSR
is part of the new Freescale "Book-E" registers.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
2008-06-26 01:49:03 -05:00
Kumar Gala
fc4033b2f8 powerpc/85xx: add DOZE/NAP support for e500 core
The e500 core enter DOZE/NAP power-saving modes when the core go to
cpu_idle routine.

The power management default running mode is DOZE, If the user

echo 1 > /proc/sys/kernel/powersave-nap

the system will change to NAP running mode.

Signed-off-by: Dave Liu <daveliu@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
2008-06-26 01:48:56 -05:00
Rene Herman
16d7523973 thermal: Create CONFIG_THERMAL_HWMON=n
A bug in libsensors <= 2.10.6 is exposed
when this new hwmon I/F is enabled.
Create CONFIG_THERMAL_HWMON=n
until some time after libsensors 2.10.7 ships
so those users can run the latest kernel.

libsensors 3.x is already fixed -- those users
can use CONFIG_THERMAL_HWMON=y now.

Signed-off-by: Rene Herman <rene.herman@gmail.com>
Acked-by: Mark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2008-06-25 19:25:42 -04:00
John W. Linville
1839cea91e Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/wireless-2.6 2008-06-25 15:17:58 -04:00
Ingo Molnar
c7e745c6de Merge commit 'v2.6.26-rc8' into core/softlockup 2008-06-25 17:49:08 +02:00
Jeremy Fitzhardinge
e57778a1e3 xen: implement ptep_modify_prot_start/commit
Xen has a pte update function which will update a pte while preserving
its accessed and dirty bits.  This means that ptep_modify_prot_start() can be
implemented as a simple read of the pte value.  The hardware may
update the pte in the meantime, but ptep_modify_prot_commit() updates it while
preserving any changes that may have happened in the meantime.

The updates in ptep_modify_prot_commit() are batched if we're currently in lazy
mmu mode.

The mmu_update hypercall can take a batch of updates to perform, but
this code doesn't make particular use of that feature, in favour of
using generic multicall batching to get them all into the hypervisor.

The net effect of this is that each mprotect pte update turns from two
expensive trap-and-emulate faults into they hypervisor into a single
hypercall whose cost is amortized in a batched multicall.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-25 15:17:23 +02:00
Jeremy Fitzhardinge
08b882c627 paravirt: add hooks for ptep_modify_prot_start/commit
This patch adds paravirt-ops hooks in pv_mmu_ops for ptep_modify_prot_start and
ptep_modify_prot_commit.  This allows the hypervisor-specific backends to
implement these in some more efficient way.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-25 15:16:00 +02:00
Jeremy Fitzhardinge
1ea0704e0d mm: add a ptep_modify_prot transaction abstraction
This patch adds an API for doing read-modify-write updates to a pte's
protection bits which may race against hardware updates to the pte.
After reading the pte, the hardware may asynchonously set the accessed
or dirty bits on a pte, which would be lost when writing back the
modified pte value.

The existing technique to handle this race is to use
ptep_get_and_clear() atomically fetch the old pte value and clear it
in memory.  This has the effect of marking the pte as non-present,
which will prevent the hardware from updating its state.  When the new
value is written back, the pte will be present again, and the hardware
can resume updating the access/dirty flags.

When running in a virtualized environment, pagetable updates are
relatively expensive, since they generally involve some trap into the
hypervisor.  To mitigate the cost of these updates, we tend to batch
them.

However, because of the atomic nature of ptep_get_and_clear(), it is
inherently non-batchable.  This new interface allows batching by
giving the underlying implementation enough information to open a
transaction between the read and write phases:

ptep_modify_prot_start() returns the current pte value, and puts the
  pte entry into a state where either the hardware will not update the
  pte, or if it does, the updates will be preserved on commit.

ptep_modify_prot_commit() writes back the updated pte, makes sure that
  any hardware updates made since ptep_modify_prot_start() are
  preserved.

ptep_modify_prot_start() and _commit() must be exactly paired, and
used while holding the appropriate pte lock.  They do not protect
against other software updates of the pte in any way.

The current implementations of ptep_modify_prot_start and _commit are
functionally unchanged from before: _start() uses ptep_get_and_clear()
fetch the pte and zero the entry, preventing any hardware updates.
_commit() simply writes the new pte value back knowing that the
hardware has not updated the pte in the meantime.

The only current user of this interface is mprotect

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-25 15:15:53 +02:00
Ingo Molnar
8700600a74 Merge branch 'linus' into x86/nmi 2008-06-25 12:31:28 +02:00
Ingo Molnar
0ed368c71a Merge branch 'linus' into x86/kconfig 2008-06-25 12:30:54 +02:00
Ingo Molnar
cbd6712406 Merge branch 'linus' into x86/irq 2008-06-25 12:30:49 +02:00
Ingo Molnar
48cf937f48 Merge branch 'linus' into x86/i8259 2008-06-25 12:30:33 +02:00
Ingo Molnar
037a6079eb Merge branch 'linus' into x86/gart 2008-06-25 12:30:26 +02:00
Ingo Molnar
8b7ef4ec5b Merge branch 'linus' into x86/fixmap 2008-06-25 12:30:21 +02:00