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2005-11-03[ARM SMP] Track CPU idle threadsRussell King1-0/+1
Track the idle thread task_struct for each CPU. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02[ARM] Fix ARM rwlock implementationsRussell King1-3/+3
fb1c8f93d869b34cacb8b8932e2b83d96a19d720 broke the ARM rwlock code since it only partially updated the rwlock implementation. Properly update it. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02[ARM] 3083/1: include/asm-arm/arch-ixp4xx/io.h: eliminate warnings for ↵John Bowler1-34/+40
pointer passed to integral function argument Patch from John Bowler Fix for a compiler warning, this wasn't apparent in 2.6.12, I believe the compiler options have been changed (somewhere) so that passing a (void*) to a (u32) argument is now warned. This accounts for the majority of the warnings in my builds of the 2.6.14 kernel for NSLU2. The patch changes pointer parameters declared as u32 to be declared as either, for read parameters: const volatile void __iomem * and for write parameters: volatile void __iomem * Signed-off-by: John Bowler <jbowler@acm.org> Signed-off-by: Deepak Saxena <dsaxena@plexity.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02[ARM] Fix realview machine type for patch 3060/1Russell King1-1/+1
Realview was missed in this cleanup... Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02[PATCH] missing platform_device.h includesAl Viro1-0/+2
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: add 5208 ColdFire reset/reboot supportGreg Ungerer1-0/+13
Add reset/reboot code to support the ColdFire 5208 family. Patch originally from Matt Wadell (from code originally written by Mike Lavender). Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: add 5208 ColdFire UART supportGreg Ungerer1-0/+4
Add support for the UARTs on the ColdFire 5208 family. Patch originally from Matt Wadell (from code originally written by Mike Lavender). Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: add 5208 ColdFire pit interrupt supportGreg Ungerer1-0/+15
The PIT timer in the 5208 ColdFire has slightly different interrupt bit definitions than the PIT timer used on other ColdFire parts. Define the commonly used bit and mask numbers here, and let part specific defines take precedence if they are defined. Patch originally from Matt Wadell (from code originally written by Mike Lavender). Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: add 5208 ColdFire pit timer supportGreg Ungerer1-2/+6
Add support for the PIT timer used in the 5208 ColdFire fmaily. Patch originally from Matt Wadell (from code originally modified by Mike Lavender). Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: use board defines to distinguish boardsGreg Ungerer1-9/+9
Use board name defines to distinguish boards, instead of combinations of more generic defines. Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: add 5208 ColdFire cache supportGreg Ungerer1-0/+14
Add support for the cpu cache of the 5208 ColdFire fmaily. Patch originally from Matt Wadell (from code originally written by Mike Lavender). Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: add 5208 ColdFire support definesGreg Ungerer1-0/+54
Add support for the internal register map of the 5208 ColdFire fmaily. Patch originally from Matt Wadell (from code originally written by Mike Lavender). Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: add 5208 ColdFire support defines for its internal mapGreg Ungerer1-2/+8
Define the register space of the new 5208 ColdFire family (which includes to 5207). It is mostly similar to the other ColdFire parts. Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: use board name defines to differentiate board definitionsGreg Ungerer1-2/+2
Use board name define to differentiate boards, not combination of more generic defines. Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: remove unmaintained asm-m68knommu/ide.hGreg Ungerer1-437/+0
Remove unmaintained asm-m68knommu/ide.h. It is completely out of date - and there is no underlying support for it. Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: remove auto-generated asm-offsets.hGreg Ungerer1-49/+0
Remove auto-generated file from source base. Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02[PATCH] m68knommu: change use of extern inline to static inline in headersGreg Ungerer8-20/+20
"extern inline" doesn't make much sense here. Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Greg Ungerer <gerg@uclinux.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-02Merge master.kernel.org:/pub/scm/linux/kernel/git/acme/net-2.6Linus Torvalds2-8/+39
2005-11-02Merge master.kernel.org:/home/rmk/linux-2.6-serialLinus Torvalds1-3/+4
2005-11-02Merge master.kernel.org:/home/rmk/linux-2.6-armLinus Torvalds19-20/+974
2005-11-01[ARM] 3052/1: add ixp2000 microcode loaderLennert Buytenhek2-2/+65
Patch from Lennert Buytenhek This patch adds a microcode loader for the ixp2000 architecture. The ixp2000 is an xscale-based CPU with a number of additional small CPUs ('microengines') on die that can be programmed to do various things. Depending on the ixp2000 model, there are between 2 and 16 microengines. This code provides an API that allows configuring the microengines, loading code into them, and starting and stopping them and reading out a number of status registers, and is used by the microengine network driver that was recently announced to netdev. Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org> Signed-off-by: Deepak Saxena <dsaxena@plexity.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01[ARM] 3077/1: S3C2410 - regs-iis.h missing mask for IISMOD_FSBen Dooks1-0/+1
Patch from Ben Dooks Add definition for S3C2410_IISMOD_FS_MASK Signed-off-by: Ben Dooks <ben-linux@fluff.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01[ARM] 3065/1: ixp2000 typo and whitespace fixesLennert Buytenhek1-1/+1
Patch from Lennert Buytenhek Misc ixp2000 typo and whitespace fixes. Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org> Signed-off-by: Deepak Saxena <dsaxena@plexity.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01[ARM] 3064/1: start using ixp2000_reg_wrbLennert Buytenhek1-8/+9
Patch from Lennert Buytenhek Switch the users of ixp2000_reg_write that depend on writes being flushed out of the write buffer by the time that function returns over to ixp2000_reg_wrb. When using XCB=101, writes to the same functional unit are still guaranteed to complete in order, so we only need to protect against: - reordering of writes to different functional units - masking an interrupt and then reenabling the IRQ bit in CPSR Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org> Signed-off-by: Deepak Saxena <dsaxena@plexity.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01[ARM] 3063/1: allow slave ixp2000 cpu resetLennert Buytenhek1-7/+1
Patch from Lennert Buytenhek On the ixdp2x00, the slave CPU is currently not allowed to reset itself for fear that it will do something 'funky' on the PCI bus. This fear is ungrounded -- the slave CPU is wired up such that a CPU reset will not cause a PCI bus reset to be done. This patch changes arch_reset() so that the slave CPU also executes the reset sequence, allowing it to reboot itself using /sbin/reboot. Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org> Signed-off-by: Deepak Saxena <dsaxena@plexity.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01[ARM] 3062/1: map in various enp2611 peripherals for the ixp2000 netdev driverLennert Buytenhek1-2/+14
Patch from Lennert Buytenhek The enp2611 version of the ixp2000 netdev driver needs to be able to access a number of on-board peripherals. ioremap() is not suitable for this, as that will cause XCB=000 mappings to be done, which will make the cpu susceptible to crashing on ixp2400 erratum #66. Properly aligned iotable mappings with MT_IXP2000_DEVICE will cause section mappings with XCB=101 to be done, which is safe. Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org> Signed-off-by: Deepak Saxena <dsaxena@plexity.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01Revert "i386: move apic init in init_IRQs"Linus Torvalds4-3/+23
Commit f2b36db692b7ff6972320ad9839ae656a3b0ee3e causes a bootup hang on at least one machine. Revert for now until we understand why. The old code may be ugly, but it works. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-01[PATCH] Creative Audigy 2 cardbus: Add IO window wakeup magicJames Courtier-Dutton1-0/+1
This adds the magic IO wakeup code for the CardBus version of the Creative Labs Audigy 2 to the snd-emu10k1 driver. Without the magic IO enable sequence, reading from the IO region of the card will fail spectacularly, and the machine will hang. My next task will be getting the driver to actually play sound without distortion. Signed-off-by: James Courtier-Dutton <James@superbug.co.uk> [ This is a work-in-progress, but since it avoids a total lockup if the emu10k module is loaded on a machine with the cardbus card inserted, we're better off with it than without it, even if sound quality is bad right now ] Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[NETFILTER]: Add "revision" support to arp_tables and ip6_tablesHarald Welte2-8/+39
Like ip_tables already has it for some time, this adds support for having multiple revisions for each match/target. We steal one byte from the name in order to accomodate a 8 bit version number. Signed-off-by: Harald Welte <laforge@netfilter.org> Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
2005-10-31Merge master.kernel.org:/home/rmk/linux-2.6-drvmodelLinus Torvalds4-28/+42
Manual #include fixups for clashes - there may be some unnecessary
2005-10-31[ARM] Add support for ARM RealView boardCatalin Marinas14-1/+884
Support for RealView EB. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-31[SERIAL] Fix port numberingRussell King1-3/+4
The PORT_* macros must be uniquely numbered. This fixes the definitions. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-31Merge ../linux-2.6 by handPaul Mackerras491-3576/+14999
2005-10-31powerpc: Fix bug arising from having multiple memory_limit variablesPaul Mackerras2-0/+2
We had a static memory_limit in prom.c, and then another one defined in setup_64.c and used in numa.c, which resulted in the kernel crashing when mem=xxx was given on the command line. This puts the declaration in system.h and the definition in mem.c. This also moves the definition of tce_alloc_start/end out of setup_64.c. Signed-off-by: Paul Mackerras <paulus@samba.org>
2005-10-31Merge master.kernel.org:/home/rmk/linux-2.6-armLinus Torvalds2-4/+4
2005-10-31[PATCH] fat: cleanup and optimization of checksumOGAWA Hirofumi1-0/+11
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] fix missing includesTim Schmielau11-2/+19
I recently picked up my older work to remove unnecessary #includes of sched.h, starting from a patch by Dave Jones to not include sched.h from module.h. This reduces the number of indirect includes of sched.h by ~300. Another ~400 pointless direct includes can be removed after this disentangling (patch to follow later). However, quite a few indirect includes need to be fixed up for this. In order to feed the patches through -mm with as little disturbance as possible, I've split out the fixes I accumulated up to now (complete for i386 and x86_64, more archs to follow later) and post them before the real patch. This way this large part of the patch is kept simple with only adding #includes, and all hunks are independent of each other. So if any hunk rejects or gets in the way of other patches, just drop it. My scripts will pick it up again in the next round. Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] cleanup the usage of SEND_SIG_xxx constantsOleg Nesterov1-0/+5
This patch simplifies some checks for magic siginfo values. It should not change the behaviour in any way. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] sched: hardcode non-smp set_cpus_allowedPaul Jackson1-1/+1
Simplify the UP (1 CPU) implementatin of set_cpus_allowed. The one CPU is hardcoded to be cpu 0 - so just test for that bit, and avoid having to pick up the cpu_online_map. Also, unexport cpu_online_map: it was only needed for set_cpus_allowed(). Signed-off-by: Paul Jackson <pj@sgi.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] semaphore: Remove __MUTEX_INITIALIZER()Arthur Othieno23-67/+0
__MUTEX_INITIALIZER() has no users, and equates to the more commonly used DECLARE_MUTEX(), thus making it pretty much redundant. Remove it for good. Signed-off-by: Arthur Othieno <a.othieno@bluewin.ch> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] RCU torture-testing kernel modulePaul E. McKenney1-0/+1
This patch is a rewrite of the one submitted on October 1st, using modules (http://marc.theaimsgroup.com/?l=linux-kernel&m=112819093522998&w=2). This rewrite adds a tristate CONFIG_RCU_TORTURE_TEST, which enables an intense torture test of the RCU infratructure. This is needed due to the continued changes to the RCU infrastructure to accommodate dynamic ticks, CPU hotplug, realtime, and so on. Most of the code is in a separate file that is compiled only if the CONFIG variable is set. Documentation on how to run the test and interpret the output is also included. This code has been tested on i386 and ppc64, and an earlier version of the code has received extensive testing on a number of architectures as part of the PREEMPT_RT patchset. Signed-off-by: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] include/linux/kernel.h:BUILD_BUG_ON(): fix a commentNikita Danilov1-1/+1
Fix comment describing BUILD_BUG_ON: BUG_ON is not an assertion (unfortunately). Signed-off-by: Nikita Danilov <nikita@clusterfs.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] modules: fix sparse warning for every MODULE_PARMPavel Roskin1-1/+3
sparse complains about every MODULE_PARM used in a module: warning: symbol '__parm_foo' was not declared. Should it be static? The fix is to split declaration and initialization. While MODULE_PARM is obsolete, it's not something sparse should report. Signed-off-by: Pavel Roskin <proski@gnu.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] fuse: remove unused defineMiklos Szeredi1-1/+0
Setting ctime is implicit in all setattr cases, so the FATTR_CTIME definition is unnecessary. It is used by neither the kernel nor by userspace. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] Keys: Add LSM hooks for key management [try #3]David Howells3-5/+84
The attached patch adds LSM hooks for key management facilities. The notable changes are: (1) The key struct now supports a security pointer for the use of security modules. This will permit key labelling and restrictions on which programs may access a key. (2) Security modules get a chance to note (or abort) the allocation of a key. (3) The key permission checking can now be enhanced by the security modules; the permissions check consults LSM if all other checks bear out. (4) The key permissions checking functions now return an error code rather than a boolean value. (5) An extra permission has been added to govern the modification of attributes (UID, GID, permissions). Note that there isn't an LSM hook specifically for each keyctl() operation, but rather the permissions hook allows control of individual operations based on the permission request bits. Key management access control through LSM is enabled by automatically if both CONFIG_KEYS and CONFIG_SECURITY are enabled. This should be applied on top of the patch ensubjected: [PATCH] Keys: Possessor permissions should be additive Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Chris Wright <chrisw@osdl.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] Keys: Export user-defined keyring operationsDavid Howells1-0/+47
Export user-defined key operations so that those who wish to define their own key type based on the user-defined key operations may do so (as has been requested). The header file created has been placed into include/keys/user-type.h, thus creating a directory where other key types may also be placed. Any objections to doing this? Signed-Off-By: David Howells <dhowells@redhat.com> Signed-Off-By: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] vm: remove unused/broken page_pte[_prot] macrosTejun Heo13-28/+0
This patch removes page_pte_prot and page_pte macros from all architectures. Some architectures define both, some only page_pte (broken) and others none. These macros are not used anywhere. page_pte_prot(page, prot) is identical to mk_pte(page, prot) and page_pte(page) is identical to page_pte_prot(page, __pgprot(0)). * The following architectures define both page_pte_prot and page_pte arm, arm26, ia64, sh64, sparc, sparc64 * The following architectures define only page_pte (broken) frv, i386, m32r, mips, sh, x86-64 * All other architectures define neither Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] cpusets: automatic numa mempolicy rebindingPaul Jackson1-0/+6
This patch automatically updates a tasks NUMA mempolicy when its cpuset memory placement changes. It does so within the context of the task, without any need to support low level external mempolicy manipulation. If a system is not using cpusets, or if running on a system with just the root (all-encompassing) cpuset, then this remap is a no-op. Only when a task is moved between cpusets, or a cpusets memory placement is changed does the following apply. Otherwise, the main routine below, rebind_policy() is not even called. When mixing cpusets, scheduler affinity, and NUMA mempolicies, the essential role of cpusets is to place jobs (several related tasks) on a set of CPUs and Memory Nodes, the essential role of sched_setaffinity is to manage a jobs processor placement within its allowed cpuset, and the essential role of NUMA mempolicy (mbind, set_mempolicy) is to manage a jobs memory placement within its allowed cpuset. However, CPU affinity and NUMA memory placement are managed within the kernel using absolute system wide numbering, not cpuset relative numbering. This is ok until a job is migrated to a different cpuset, or what's the same, a jobs cpuset is moved to different CPUs and Memory Nodes. Then the CPU affinity and NUMA memory placement of the tasks in the job need to be updated, to preserve their cpuset-relative position. This can be done for CPU affinity using sched_setaffinity() from user code, as one task can modify anothers CPU affinity. This cannot be done from an external task for NUMA memory placement, as that can only be modified in the context of the task using it. However, it easy enough to remap a tasks NUMA mempolicy automatically when a task is migrated, using the existing cpuset mechanism to trigger a refresh of a tasks memory placement after its cpuset has changed. All that is needed is the old and new nodemask, and notice to the task that it needs to rebind its mempolicy. The tasks mems_allowed has the old mask, the tasks cpuset has the new mask, and the existing cpuset_update_current_mems_allowed() mechanism provides the notice. The bitmap/cpumask/nodemask remap operators provide the cpuset relative calculations. This patch leaves open a couple of issues: 1) Updating vma and shmfs/tmpfs/hugetlbfs memory policies: These mempolicies may reference nodes outside of those allowed to the current task by its cpuset. Tasks are migrated as part of jobs, which reside on what might be several cpusets in a subtree. When such a job is migrated, all NUMA memory policy references to nodes within that cpuset subtree should be translated, and references to any nodes outside that subtree should be left untouched. A future patch will provide the cpuset mechanism needed to mark such subtrees. With that patch, we will be able to correctly migrate these other memory policies across a job migration. 2) Updating cpuset, affinity and memory policies in user space: This is harder. Any placement state stored in user space using system-wide numbering will be invalidated across a migration. More work will be required to provide user code with a migration-safe means to manage its cpuset relative placement, while preserving the current API's that pass system wide numbers, not cpuset relative numbers across the kernel-user boundary. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] cpusets: bitmap and mask remap operatorsPaul Jackson3-0/+46
In the forthcoming task migration support, a key calculation will be mapping cpu and node numbers from the old set to the new set while preserving cpuset-relative offset. For example, if a task and its pages on nodes 8-11 are being migrated to nodes 24-27, then pages on node 9 (the 2nd node in the old set) should be moved to node 25 (the 2nd node in the new set.) As with other bitmap operations, the proper way to code this is to provide the underlying calculation in lib/bitmap.c, and then to provide the usual cpumask and nodemask wrappers. This patch provides that. These operations are termed 'remap' operations. Both remapping a single bit and a set of bits is supported. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-31[PATCH] cpusets: dual semaphore locking overhaulPaul Jackson1-1/+1
Overhaul cpuset locking. Replace single semaphore with two semaphores. The suggestion to use two locks was made by Roman Zippel. Both locks are global. Code that wants to modify cpusets must first acquire the exclusive manage_sem, which allows them read-only access to cpusets, and holds off other would-be modifiers. Before making actual changes, the second semaphore, callback_sem must be acquired as well. Code that needs only to query cpusets must acquire callback_sem, which is also a global exclusive lock. The earlier problems with double tripping are avoided, because it is allowed for holders of manage_sem to nest the second callback_sem lock, and only callback_sem is needed by code called from within __alloc_pages(), where the double tripping had been possible. This is not quite the same as a normal read/write semaphore, because obtaining read-only access with intent to change must hold off other such attempts, while allowing read-only access w/o such intention. Changing cpusets involves several related checks and changes, which must be done while allowing read-only queries (to avoid the double trip), but while ensuring nothing changes (holding off other would be modifiers.) This overhaul of cpuset locking also makes careful use of task_lock() to guard access to the task->cpuset pointer, closing a couple of race conditions noticed while reading this code (thanks, Roman). I've never seen these races fail in any use or test. See further the comments in the code. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>