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* kernel/cpu.c: fix many errors related to style.Michael Rodriguez2011-03-221-6/+5
| | | | | | | | | | Change the printk() calls to have the KERN_INFO/KERN_ERROR stuff, and fixes other coding style errors. Not _all_ of them are gone, though. [akpm@linux-foundation.org: revert the bits I disagree with] Signed-off-by: Michael Rodriguez <dkingston02@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
*-. Merge branches 'x86-alternatives-for-linus', 'x86-fpu-for-linus', ↵Linus Torvalds2011-01-061-0/+11
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'x86-hwmon-for-linus', 'x86-paravirt-for-linus', 'core-locking-for-linus' and 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-alternatives-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, suspend: Avoid unnecessary smp alternatives switch during suspend/resume * 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86-64, asm: Use fxsaveq/fxrestorq in more places * 'x86-hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, hwmon: Add core threshold notification to therm_throt.c * 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, paravirt: Use native_halt on a halt, not native_safe_halt * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: locking, lockdep: Convert sprintf_symbol to %pS * 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: irq: Better struct irqaction layout
| * | x86, suspend: Avoid unnecessary smp alternatives switch during suspend/resumeSuresh Siddha2010-12-131-0/+11
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | During suspend, we disable all the non boot cpus. And during resume we bring them all back again. So no need to do alternatives_smp_switch() in between. On my core 2 based laptop, this speeds up the suspend path by 15msec and the resume path by 5 msec (suspend/resume speed up differences can be attributed to the different P-states that the cpu is in during suspend/resume). Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <1290557500.4946.8.camel@sbsiddha-MOBL3.sc.intel.com> Cc: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
* | cpu: Remove incorrect BUG_ONPeter Zijlstra2010-11-231-1/+4
| | | | | | | | | | | | | | | | | | | | | | Oleg mentioned that there is no actual guarantee the dying cpu's migration thread is actually finished running when we get there, so replace the BUG_ON() with a spinloop waiting for it. Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | cpu: Remove unused variableDhaval Giani2010-11-231-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | GCC warns us about: kernel/cpu.c: In function ‘take_cpu_down’: kernel/cpu.c:200:15: warning: unused variable ‘cpu’ This variable is unused since param->hcpu is directly used later on in cpu_notify. Signed-off-by: Dhaval Giani <dhaval_giani@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1290091494.1145.5.camel@gondor.retis> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | sched: Simplify cpu-hot-unplug task migrationPeter Zijlstra2010-11-181-10/+6
|/ | | | | | | | | | | | | | | | | | | | | While discussing the need for sched_idle_next(), Oleg remarked that since try_to_wake_up() ensures sleeping tasks will end up running on a sane cpu, we can do away with migrate_live_tasks(). If we then extend the existing hack of migrating current from CPU_DYING to migrating the full rq worth of tasks from CPU_DYING, the need for the sched_idle_next() abomination disappears as well, since idle will be the only possible thread left after the migration thread stops. This greatly simplifies the hot-unplug task migration path, as can be seen from the resulting code reduction (and about half the new lines are comments). Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1289851597.2109.547.camel@laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: adjust when cpu_active and cpuset configurations are updated during ↵Tejun Heo2010-06-081-6/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | cpu on/offlining Currently, when a cpu goes down, cpu_active is cleared before CPU_DOWN_PREPARE starts and cpuset configuration is updated from a default priority cpu notifier. When a cpu is coming up, it's set before CPU_ONLINE but cpuset configuration again is updated from the same cpu notifier. For cpu notifiers, this presents an inconsistent state. Threads which a CPU_DOWN_PREPARE notifier expects to be bound to the CPU can be migrated to other cpus because the cpu is no more inactive. Fix it by updating cpu_active in the highest priority cpu notifier and cpuset configuration in the second highest when a cpu is coming up. Down path is updated similarly. This guarantees that all other cpu notifiers see consistent cpu_active and cpuset configuration. cpuset_track_online_cpus() notifier is converted to cpuset_update_active_cpus() which just updates the configuration and now called from cpuset_cpu_[in]active() notifiers registered from sched_init_smp(). If cpuset is disabled, cpuset_update_active_cpus() degenerates into partition_sched_domains() making separate notifier for !CONFIG_CPUSETS unnecessary. This problem is triggered by cmwq. During CPU_DOWN_PREPARE, hotplug callback creates a kthread and kthread_bind()s it to the target cpu, and the thread is expected to run on that cpu. * Ingo's test discovered __cpuinit/exit markups were incorrect. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Menage <menage@google.com>
* fix cpu_chain section mismatch...Daniel J Blueman2010-06-011-1/+1
| | | | | | | | | | | | | | In commit e9fb7631ebcd ("cpu-hotplug: introduce cpu_notify(), __cpu_notify(), cpu_notify_nofail()") the new helper functions access cpu_chain. As a result, it shouldn't be marked __cpuinitdata (via section mismatch warning). Alternatively, the helper functions should be forced inline, or marked __ref or __cpuinit. In the meantime, this patch silences the warning the trivial way. Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* CPU: Avoid using unititialized error variable in disable_nonboot_cpus()Rafael J. Wysocki2010-05-301-1/+1
| | | | | | | | | | If there's only one CPU online when disable_nonboot_cpus() is called, the error variable will not be initialized and that may lead to erroneous behavior. Fix this issue by initializing error in disable_nonboot_cpus() as appropriate. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Avoid warning when CPU hotplug isn't enabledLinus Torvalds2010-05-271-6/+3
| | | | | | | | | | | | | | | Commit e9fb7631ebcd ("cpu-hotplug: introduce cpu_notify(), __cpu_notify(), cpu_notify_nofail()") also introduced this annoying warning: kernel/cpu.c:157: warning: 'cpu_notify_nofail' defined but not used when CONFIG_HOTPLUG_CPU wasn't set. So move that helper inside the #ifdef CONFIG_HOTPLUG_CPU region, and simplify it while at it. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* cpuhotplug: do not need cpu_hotplug_begin() when CONFIG_HOTPLUG_CPU=nLai Jiangshan2010-05-271-18/+22
| | | | | | | | | | | | | | | Since when CONFIG_HOTPLUG_CPU=n, get_online_cpus() do nothing, so we don't need cpu_hotplug_begin() either. This patch moves cpu_hotplug_begin()/cpu_hotplug_done() into the code block of CONFIG_HOTPLUG_CPU=y. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* cpu-hotplug: return better errno on cpu hotplug failureAkinobu Mita2010-05-271-6/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | Currently, onlining or offlining a CPU failure by one of the cpu notifiers error always cause -EINVAL error. (i.e. writing 0 or 1 to /sys/devices/system/cpu/cpuX/online gets EINVAL) To get better error reporting rather than always getting -EINVAL, This changes cpu_notify() to return -errno value with notifier_to_errno() and fix the callers. Now that cpu notifiers can return encapsulate errno value. Currently, all cpu hotplug notifiers return NOTIFY_OK, NOTIFY_BAD, or NOTIFY_DONE. So cpu_notify() can returns 0 or -EPERM with this change for now. (notifier_to_errno(NOTIFY_OK) == 0, notifier_to_errno(NOTIFY_DONE) == 0, notifier_to_errno(NOTIFY_BAD) == -EPERM) Forthcoming patches convert several cpu notifiers to return encapsulate errno value with notifier_from_errno(). Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* cpu-hotplug: introduce cpu_notify(), __cpu_notify(), cpu_notify_nofail()Akinobu Mita2010-05-271-23/+31
| | | | | | | | | | No functional change. These are just wrappers of raw_cpu_notifier_call_chain. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mem-hotplug: fix potential race while building zonelist for new populated zoneHaicheng Li2010-05-251-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add global mutex zonelists_mutex to fix the possible race: CPU0 CPU1 CPU2 (1) zone->present_pages += online_pages; (2) build_all_zonelists(); (3) alloc_page(); (4) free_page(); (5) build_all_zonelists(); (6) __build_all_zonelists(); (7) zone->pageset = alloc_percpu(); In step (3,4), zone->pageset still points to boot_pageset, so bad things may happen if 2+ nodes are in this state. Even if only 1 node is accessing the boot_pageset, (3) may still consume too much memory to fail the memory allocations in step (7). Besides, atomic operation ensures alloc_percpu() in step (7) will never fail since there is a new fresh memory block added in step(6). [haicheng.li@linux.intel.com: hold zonelists_mutex when build_all_zonelists] Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Andi Kleen <andi.kleen@intel.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mem-hotplug: avoid multiple zones sharing same boot strapping boot_pagesetHaicheng Li2010-05-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For each new populated zone of hotadded node, need to update its pagesets with dynamically allocated per_cpu_pageset struct for all possible CPUs: 1) Detach zone->pageset from the shared boot_pageset at end of __build_all_zonelists(). 2) Use mutex to protect zone->pageset when it's still shared in onlined_pages() Otherwises, multiple zones of different nodes would share same boot strapping boot_pageset for same CPU, which will finally cause below kernel panic: ------------[ cut here ]------------ kernel BUG at mm/page_alloc.c:1239! invalid opcode: 0000 [#1] SMP ... Call Trace: [<ffffffff811300c1>] __alloc_pages_nodemask+0x131/0x7b0 [<ffffffff81162e67>] alloc_pages_current+0x87/0xd0 [<ffffffff81128407>] __page_cache_alloc+0x67/0x70 [<ffffffff811325f0>] __do_page_cache_readahead+0x120/0x260 [<ffffffff81132751>] ra_submit+0x21/0x30 [<ffffffff811329c6>] ondemand_readahead+0x166/0x2c0 [<ffffffff81132ba0>] page_cache_async_readahead+0x80/0xa0 [<ffffffff8112a0e4>] generic_file_aio_read+0x364/0x670 [<ffffffff81266cfa>] nfs_file_read+0xca/0x130 [<ffffffff8117b20a>] do_sync_read+0xfa/0x140 [<ffffffff8117bf75>] vfs_read+0xb5/0x1a0 [<ffffffff8117c151>] sys_read+0x51/0x80 [<ffffffff8103c032>] system_call_fastpath+0x16/0x1b RIP [<ffffffff8112ff13>] get_page_from_freelist+0x883/0x900 RSP <ffff88000d1e78a8> ---[ end trace 4bda28328b9990db ] [akpm@linux-foundation.org: merge fix] Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Andi Kleen <andi.kleen@intel.com> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* cpu/mem hotplug: enable CPUs online before local memory onlineminskey guo2010-05-251-0/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | Enable users to online CPUs even if the CPUs belongs to a numa node which doesn't have onlined local memory. The zonlists(pg_data_t.node_zonelists[]) of a numa node are created either in system boot/init period, or at the time of local memory online. For a numa node without onlined local memory, its zonelists are not initialized at present. As a result, any memory allocation operations executed by CPUs within this node will fail. In fact, an out-of-memory error is triggered when attempt to online CPUs before memory comes to online. This patch tries to create zonelists for such numa nodes, so that the memory allocation for this node can be fallback'ed to other nodes. [akpm@linux-foundation.org: remove unneeded export] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: minskey guo<chaohong.guo@intel.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* stop_machine: reimplement using cpu_stopTejun Heo2010-05-061-8/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Reimplement stop_machine using cpu_stop. As cpu stoppers are guaranteed to be available for all online cpus, stop_machine_create/destroy() are no longer necessary and removed. With resource management and synchronization handled by cpu_stop, the new implementation is much simpler. Asking the cpu_stop to execute the stop_cpu() state machine on all online cpus with cpu hotplug disabled is enough. stop_machine itself doesn't need to manage any global resources anymore, so all per-instance information is rolled into struct stop_machine_data and the mutex and all static data variables are removed. The previous implementation created and destroyed RT workqueues as necessary which made stop_machine() calls highly expensive on very large machines. According to Dimitri Sivanich, preventing the dynamic creation/destruction makes booting faster more than twice on very large machines. cpu_stop resources are preallocated for all online cpus and should have the same effect. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Dimitri Sivanich <sivanich@sgi.com>
* Merge branch 'linus' into sched/coreIngo Molnar2010-04-151-0/+1
|\ | | | | | | | | | | Merge reason: merge the latest fixes, update to -rc4. Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * include cleanup: Update gfp.h and slab.h includes to prepare for breaking ↵Tejun Heo2010-03-301-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
* | sched: _cpu_down(): Don't play with current->cpus_allowedOleg Nesterov2010-04-021-12/+6
|/ | | | | | | | | | | | | | | | | _cpu_down() changes the current task's affinity and then recovers it at the end. The problems are well known: we can't restore old_allowed if it was bound to the now-dead-cpu, and we can race with the userspace which can change cpu-affinity during unplug. _cpu_down() should not play with current->cpus_allowed at all. Instead, take_cpu_down() can migrate the caller of _cpu_down() after __cpu_disable() removes the dying cpu from cpu_online_mask. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100315091023.GA9148@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* kernel/cpu.c: delete deprecated definition in cpu_up()Chen Gong2010-03-061-1/+1
| | | | | | | | | | | Additional_cpus is only supported for IA64 now. X86_64 should not be included. Signed-off-by: Chen Gong <gong.chen@linux.intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched: Correct printk whitespace in warning from cpu down task checkFrans Pop2010-01-281-4/+4
| | | | | | | | | | | | | | | | Due to an incorrect line break the output currently contains tabs. Also remove trailing space. The actual output that logcheck sent me looked like this: Task events/1 (pid = 10) is on cpu 1^I^I^I^I(state = 1, flags = 84208040) After this patch it becomes: Task events/1 (pid = 10) is on cpu 1 (state = 1, flags = 84208040) Signed-off-by: Frans Pop <elendilplanet.nl> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <201001251456.34996.elendil@planet.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Fix incorrect sanity checkPeter Zijlstra2010-01-281-1/+1
| | | | | | | | | | We moved to migrate on wakeup, which means that sleeping tasks could still be present on offline cpus. Amend the check to only test running tasks. Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Fix set_cpu_active() in cpu_down()Xiaotian Feng2009-12-161-21/+3
| | | | | | | | | | | | | | | | | | | | Sachin found cpu hotplug test failures on powerpc, which made the kernel hang on his POWER box. The problem is that we fail to re-activate a cpu when a hot-unplug fails. Fix this by moving the de-activation into _cpu_down after doing the initial checks. Remove the synchronize_sched() calls and rely on those implied by rebuilding the sched domains using the new mask. Reported-by: Sachin Sant <sachinp@in.ibm.com> Signed-off-by: Xiaotian Feng <dfeng@redhat.com> Tested-by: Sachin Sant <sachinp@in.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> LKML-Reference: <20091216170517.500272612@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Merge branch 'sched-fixes-for-linus' of ↵Linus Torvalds2009-12-121-5/+13
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (21 commits) sched: Remove forced2_migrations stats sched: Fix memory leak in two error corner cases sched: Fix build warning in get_update_sysctl_factor() sched: Update normalized values on user updates via proc sched: Make tunable scaling style configurable sched: Fix missing sched tunable recalculation on cpu add/remove sched: Fix task priority bug sched: cgroup: Implement different treatment for idle shares sched: Remove unnecessary RCU exclusion sched: Discard some old bits sched: Clean up check_preempt_wakeup() sched: Move update_curr() in check_preempt_wakeup() to avoid redundant call sched: Sanitize fork() handling sched: Clean up ttwu() rq locking sched: Remove rq->clock coupling from set_task_cpu() sched: Consolidate select_task_rq() callers sched: Remove sysctl.sched_features sched: Protect sched_rr_get_param() access to task->sched_class sched: Protect task->cpus_allowed access in sched_getaffinity() sched: Fix balance vs hotplug race ... Fixed up conflicts in kernel/sysctl.c (due to sysctl cleanup)
| * sched: Fix balance vs hotplug racePeter Zijlstra2009-12-061-5/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since (e761b77: cpu hotplug, sched: Introduce cpu_active_map and redo sched domain managment) we have cpu_active_mask which is suppose to rule scheduler migration and load-balancing, except it never (fully) did. The particular problem being solved here is a crash in try_to_wake_up() where select_task_rq() ends up selecting an offline cpu because select_task_rq_fair() trusts the sched_domain tree to reflect the current state of affairs, similarly select_task_rq_rt() trusts the root_domain. However, the sched_domains are updated from CPU_DEAD, which is after the cpu is taken offline and after stop_machine is done. Therefore it can race perfectly well with code assuming the domains are right. Cure this by building the domains from cpu_active_mask on CPU_DOWN_PREPARE. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | timers, init: Limit the number of per cpu calibration bootup messagesMike Travis2009-11-261-3/+2
|/ | | | | | | | | | | | | | | | | | | | | | | | | Limit the number of per cpu calibration messages by only printing out results for the first cpu to boot. Also, don't print "CPUx is down" as this is expected, and we don't need 4096 reminders... ;-) Signed-off-by: Mike Travis <travis@sgi.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Roland Dreier <rdreier@cisco.com> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: Tejun Heo <tj@kernel.org> Cc: Andi Kleen <andi@firstfloor.org> Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Yinghai Lu <yhlu.kernel@gmail.com> Cc: David Rientjes <rientjes@google.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> Cc: Jack Steiner <steiner@sgi.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <20091118002219.889552000@alcatraz.americas.sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Merge branch 'x86-pat-for-linus' of ↵Linus Torvalds2009-09-151-0/+14
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-pat-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, pat: Fix cacheflush address in change_page_attr_set_clr() mm: remove !NUMA condition from PAGEFLAGS_EXTENDED condition set x86: Fix earlyprintk=dbgp for machines without NX x86, pat: Sanity check remap_pfn_range for RAM region x86, pat: Lookup the protection from memtype list on vm_insert_pfn() x86, pat: Add lookup_memtype to get the current memtype of a paddr x86, pat: Use page flags to track memtypes of RAM pages x86, pat: Generalize the use of page flag PG_uncached x86, pat: Add rbtree to do quick lookup in memtype tracking x86, pat: Add PAT reserve free to io_mapping* APIs x86, pat: New i/f for driver to request memtype for IO regions x86, pat: ioremap to follow same PAT restrictions as other PAT users x86, pat: Keep identity maps consistent with mmaps even when pat_disabled x86, mtrr: make mtrr_aps_delayed_init static bool x86, pat/mtrr: Rendezvous all the cpus for MTRR/PAT init generic-ipi: Allow cpus not yet online to call smp_call_function with irqs disabled x86: Fix an incorrect argument of reserve_bootmem() x86: Fix system crash when loading with "reservetop" parameter
| * x86, pat/mtrr: Rendezvous all the cpus for MTRR/PAT initSuresh Siddha2009-08-211-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | SDM Vol 3a section titled "MTRR considerations in MP systems" specifies the need for synchronizing the logical cpu's while initializing/updating MTRR. Currently Linux kernel does the synchronization of all cpu's only when a single MTRR register is programmed/updated. During an AP online (during boot/cpu-online/resume) where we initialize all the MTRR/PAT registers, we don't follow this synchronization algorithm. This can lead to scenarios where during a dynamic cpu online, that logical cpu is initializing MTRR/PAT with cache disabled (cr0.cd=1) etc while other logical HT sibling continue to run (also with cache disabled because of cr0.cd=1 on its sibling). Starting from Westmere, VMX transitions with cr0.cd=1 don't work properly (because of some VMX performance optimizations) and the above scenario (with one logical cpu doing VMX activity and another logical cpu coming online) can result in system crash. Fix the MTRR initialization by doing rendezvous of all the cpus. During boot and resume, we delay the MTRR/PAT init for APs till all the logical cpu's come online and the rendezvous process at the end of AP's bringup, will initialize the MTRR/PAT for all AP's. For dynamic single cpu online, we synchronize all the logical cpus and do the MTRR/PAT init on the AP that is coming online. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
* | x86, intel_txt: clean up the impact on generic code, unbreak non-x86Shane Wang2009-09-011-5/+1
| | | | | | | | | | | | | | | | | | Move tboot.h from asm to linux to fix the build errors of intel_txt patch on non-X86 platforms. Remove the tboot code from generic code init/main.c and kernel/cpu.c. Signed-off-by: Shane Wang <shane.wang@intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
* | x86, intel_txt: Intel TXT Sx shutdown supportJoseph Cihula2009-07-211-1/+6
|/ | | | | | | | | | | | | | | | | | | | | | | Support for graceful handling of sleep states (S3/S4/S5) after an Intel(R) TXT launch. Without this patch, attempting to place the system in one of the ACPI sleep states (S3/S4/S5) will cause the TXT hardware to treat this as an attack and will cause a system reset, with memory locked. Not only may the subsequent memory scrub take some time, but the platform will be unable to enter the requested power state. This patch calls back into the tboot so that it may properly and securely clean up system state and clear the secrets-in-memory flag, after which it will place the system into the requested sleep state using ACPI information passed by the kernel. arch/x86/kernel/smpboot.c | 2 ++ drivers/acpi/acpica/hwsleep.c | 3 +++ kernel/cpu.c | 7 ++++++- 3 files changed, 11 insertions(+), 1 deletion(-) Signed-off-by: Joseph Cihula <joseph.cihula@intel.com> Signed-off-by: Shane Wang <shane.wang@intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
* mm/init: cpu_hotplug_init() must be initialized before SLABLinus Torvalds2009-06-221-8/+5
| | | | | | | | | | | | | | | | | | SLAB uses get/put_online_cpus() which use a mutex which is itself only initialized when cpu_hotplug_init() is called. Currently we hang suring boot in SLAB due to doing that too late. Reported by James Bottomley and Sachin Sant (and possibly others). Debugged by Benjamin Herrenschmidt. This just removes the dynamic initialization of the data structures, and replaces it with a static one, avoiding this dependency entirely, and removing one unnecessary special initcall. Tested-by: Sachin Sant <sachinp@in.ibm.com> Tested-by: James Bottomley <James.Bottomley@HansenPartnership.com> Tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* cpumask: use set_cpu_active in init/main.cRusty Russell2009-03-301-3/+3
| | | | | | | | cpu_active_map is deprecated in favor of cpu_active_mask, which is const for safety: we use accessors now (set_cpu_active) is we really want to make a change. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* stop_machine/cpu hotplug: fix disable_nonboot_cpusHeiko Carstens2009-01-071-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | disable_nonboot_cpus calls _cpu_down. But _cpu_down requires that the caller already created the stop_machine workqueue (like cpu_down does). Otherwise a call to stop_machine will lead to accesses to random memory regions. When introducing this new interface (9ea09af3bd3090e8349ca2899ca2011bd94cda85 "stop_machine: introduce stop_machine_create/destroy") I missed the second call site of _cpu_down. So add the missing stop_machine_create/destroy calls to disable_nonboot_cpus as well. Fixes suspend-to-ram/disk and also this bug: [ 286.547348] BUG: unable to handle kernel paging request at 6b6b6b6b [ 286.548940] IP: [<c0150ca4>] __stop_machine+0x88/0xe3 [ 286.550598] Oops: 0002 [#1] SMP [ 286.560580] Pid: 3273, comm: halt Not tainted (2.6.28-06127-g238c6d5 [ 286.560580] EIP: is at __stop_machine+0x88/0xe3 [ 286.560580] Process halt (pid: 3273, ti=f1a28000 task=f4530f30 [ 286.560580] Call Trace: [ 286.560580] [<c03d04e4>] ? _cpu_down+0x10f/0x234 [ 286.560580] [<c012a57e>] ? disable_nonboot_cpus+0x58/0xdc [ 286.560580] [<c01360c0>] ? kernel_poweroff+0x22/0x39 [ 286.560580] [<c0136301>] ? sys_reboot+0xde/0x14c [ 286.560580] [<c01331b2>] ? complete_signal+0x179/0x191 [ 286.560580] [<c0133396>] ? send_signal+0x1cc/0x1e1 [ 286.560580] [<c03de418>] ? _spin_unlock_irqrestore+0x2d/0x3c [ 286.560580] [<c0133b65>] ? group_send_signal_info+0x58/0x61 [ 286.560580] [<c0133b9e>] ? kill_pid_info+0x30/0x3a [ 286.560580] [<c0133d49>] ? sys_kill+0x75/0x13a [ 286.560580] [<c01a06cb>] ? mntput_no_expire+ox1f/0x101 [ 286.560580] [<c019b3b3>] ? dput+0x1e/0x105 [ 286.560580] [<c018ef87>] ? __fput+0x150/0x158 [ 286.560580] [<c0157abf>] ? audit_syscall_entry+0x137/0x159 [ 286.560580] [<c010329f>] ? sysenter_do_call+0x12/0x34 Reported-and-tested-by: "Justin P. Mattock" <justinmattock@gmail.com> Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Tested-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* stop_machine: introduce stop_machine_create/destroy.Heiko Carstens2009-01-051-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | Introduce stop_machine_create/destroy. With this interface subsystems that need a non-failing stop_machine environment can create the stop_machine machine threads before actually calling stop_machine. When the threads aren't needed anymore they can be killed with stop_machine_destroy again. When stop_machine gets called and the threads aren't present they will be created and destroyed automatically. This restores the old behaviour of stop_machine. This patch also converts cpu hotplug to the new interface since it is special: cpu_down calls __stop_machine instead of stop_machine. However the kstop threads will only be created when stop_machine gets called. Changing the code so that the threads would be created automatically on __stop_machine is currently not possible: when __stop_machine gets called we hold cpu_add_remove_lock, which is the same lock that create_rt_workqueue would take. So the workqueue needs to be created before the cpu hotplug code locks cpu_add_remove_lock. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* cpumask: convert kernel/cpu.cRusty Russell2009-01-011-19/+29
| | | | | | | | | | | | Impact: Reduce kernel stack and memory usage, use new cpumask API. Use cpumask_var_t for take_cpu_down() stack var, and frozen_cpus. Note that notify_cpu_starting() can be called before core_initcall allocates frozen_cpus, but the NULL check is optimized out by gcc for the CONFIG_CPUMASK_OFFSTACK=n case. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* cpumask: make set_cpu_*/init_cpu_* out-of-lineRusty Russell2008-12-301-0/+47
| | | | | | | | | | | | | | | They're only for use in boot/cpu hotplug code anyway, and this avoids the use of deprecated cpu_*_map. Stephen Rothwell points out that gcc 4.2.4 (on powerpc at least) didn't like the cast away of const anyway: include/linux/cpumask.h: In function 'set_cpu_possible': include/linux/cpumask.h:1052: warning: passing argument 2 of 'cpumask_set_cpu' discards qualifiers from pointer target type So this kills two birds with one stone. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* cpumask: switch over to cpu_online/possible/active/present_mask: coreRusty Russell2008-12-301-26/+23
| | | | | | | | | | | | | | Impact: cleanup This implements the obsolescent cpu_online_map in terms of cpu_online_mask, rather than the other way around. Same for the other maps. The documentation comments are also updated to refer to _mask rather than _map. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Mike Travis <travis@sgi.com>
* cpumask: centralize cpu_online_map and cpu_possible_mapRusty Russell2008-12-131-5/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: cleanup Each SMP arch defines these themselves. Move them to a central location. Twists: 1) Some archs (m32, parisc, s390) set possible_map to all 1, so we add a CONFIG_INIT_ALL_POSSIBLE for this rather than break them. 2) mips and sparc32 '#define cpu_possible_map phys_cpu_present_map'. Those archs simply have phys_cpu_present_map replaced everywhere. 3) Alpha defined cpu_possible_map to cpu_present_map; this is tricky so I just manipulate them both in sync. 4) IA64, cris and m32r have gratuitous 'extern cpumask_t cpu_possible_map' declarations. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Reviewed-by: Grant Grundler <grundler@parisc-linux.org> Tested-by: Tony Luck <tony.luck@intel.com> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Mike Travis <travis@sgi.com> Cc: ink@jurassic.park.msu.ru Cc: rmk@arm.linux.org.uk Cc: starvik@axis.com Cc: tony.luck@intel.com Cc: takata@linux-m32r.org Cc: ralf@linux-mips.org Cc: grundler@parisc-linux.org Cc: paulus@samba.org Cc: schwidefsky@de.ibm.com Cc: lethal@linux-sh.org Cc: wli@holomorphy.com Cc: davem@davemloft.net Cc: jdike@addtoit.com Cc: mingo@redhat.com
* cpuinit fixes in kernel/*Al Viro2008-11-301-1/+1
| | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* cpumask: introduce new API, without changing anythingRusty Russell2008-11-061-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: introduce new APIs We want to deprecate cpumasks on the stack, as we are headed for gynormous numbers of CPUs. Eventually, we want to head towards an undefined 'struct cpumask' so they can never be declared on stack. 1) New cpumask functions which take pointers instead of copies. (cpus_* -> cpumask_*) 2) Several new helpers to reduce requirements for temporary cpumasks (cpumask_first_and, cpumask_next_and, cpumask_any_and) 3) Helpers for declaring cpumasks on or offstack for large NR_CPUS (cpumask_var_t, alloc_cpumask_var and free_cpumask_var) 4) 'struct cpumask' for explicitness and to mark new-style code. 5) Make iterator functions stop at nr_cpu_ids (a runtime constant), not NR_CPUS for time efficiency and for smaller dynamic allocations in future. 6) cpumask_copy() so we can allocate less than a full cpumask eventually (for alloc_cpumask_var), and so we can eliminate the 'struct cpumask' definition eventually. 7) work_on_cpu() helper for doing task on a CPU, rather than saving old cpumask for current thread and manipulating it. 8) smp_call_function_many() which is smp_call_function_mask() except taking a cpumask pointer. Note that this patch simply introduces the new functions and leaves the obsolescent ones in place. This is to simplify the transition patches. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
*-. Merge branches 'sched/devel', 'sched/cpu-hotplug', 'sched/cpusets' and ↵Ingo Molnar2008-10-081-2/+22
|\ \ | | | | | | | | | 'sched/urgent' into sched/core
| | * kernel/cpu.c: create a CPU_STARTING cpu_chain notifierManfred Spraul2008-09-081-0/+19
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Right now, there is no notifier that is called on a new cpu, before the new cpu begins processing interrupts/softirqs. Various kernel function would need that notification, e.g. kvm works around by calling smp_call_function_single(), rcu polls cpu_online_map. The patch adds a CPU_STARTING notification. It also adds a helper function that sends the message to all cpu_chain handlers. Tested on x86-64. All other archs are untested. Especially on sparc, I'm not sure if I got it right. Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * kernel/cpu.c: Move the CPU_DYING notifiersManfred Spraul2008-09-061-2/+3
|/ | | | | | | | | | | | | | | | | | | | | | | | When a cpu is taken offline, the CPU_DYING notifiers are called on the dying cpu. According to <linux/notifiers.h>, the cpu should be "not running any task, not handling interrupts, soon dead". For the current implementation, this is not true: - __cpu_disable can fail. If it fails, then the cpu will remain alive and happy. - At least on x86, __cpu_disable() briefly enables the local interrupts to handle any outstanding interrupts. What about moving CPU_DYING down a few lines, behind the __cpu_disable() line? There are only two CPU_DYING handlers in the kernel right now: one in kvm, one in the scheduler. Both should work with the patch applied [and: I'm not sure if either one handles a failing __cpu_disable()] The patch survives simple offlining a cpu. kvm untested due to lack of a test setup. Signed-off-By: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* cpu hotplug: s390 doesn't support additional_cpus anymore.Heiko Carstens2008-08-121-1/+1
| | | | | | | | | | | s390 doesn't support the additional_cpus kernel parameter anymore since a long time. So we better update the code and documentation to reflect that. Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched, cpu hotplug: fix set_cpus_allowed() use in hotplug callbacksDmitry Adamushko2008-08-111-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mark Langsdorf reported: > One of my co-workers noticed that the powernow-k8 > driver no longer restarts when a CPU core is > hot-disabled and then hot-enabled on AMD quad-core > systems. > > The following comands work fine on 2.6.26 and fail > on 2.6.27-rc1: > > echo 0 > /sys/devices/system/cpu/cpu3/online > echo 1 > /sys/devices/system/cpu/cpu3/online > find /sys -name cpufreq > > For 2.6.26, the find will return a cpufreq > directory for each processor. In 2.6.27-rc1, > the cpu3 directory is missing. > > After digging through the code, the following > logic is failing when the core is hot-enabled > at runtime. The code works during the boot > sequence. > > cpumask_t = current->cpus_allowed; > set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu)); > if (smp_processor_id() != cpu) > return -ENODEV; So set the CPU active before calling the CPU_ONLINE notifier chain, there are a handful of notifiers that use set_cpus_allowed(). This fix also solves the problem with x86-microcode. I've sent alternative patches for microcode, but as this "rely on set_cpus_allowed_ptr() being workable in cpu-hotplug(CPU_ONLINE, ...)" assumption seems to be more broad than what we thought, perhaps this fix should be applied. With this patch we define that by the moment CPU_ONLINE is being sent, a 'cpu' is online and ready for tasks to be migrated onto it. Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Reported-by: Mark Langsdorf <mark.langsdorf@amd.com> Tested-by: Mark Langsdorf <mark.langsdorf@amd.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Merge branch 'linus' into cpus4096Ingo Molnar2008-07-281-11/+5
|\ | | | | | | | | | | | | | | Conflicts: kernel/stop_machine.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * stop_machine(): stop_machine_run() changed to use cpu maskRusty Russell2008-07-281-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | Instead of a "cpu" arg with magic values NR_CPUS (any cpu) and ~0 (all cpus), pass a cpumask_t. Allow NULL for the common case (where we don't care which CPU the function is run on): temporary cpumask_t's are usually considered bad for stack space. This deprecates stop_machine_run, to be removed soon when all the callers are dead. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
| * Hotplug CPU: don't check cpu_online after take_cpu_downRusty Russell2008-07-281-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Akinobu points out that if take_cpu_down() succeeds, the cpu must be offline. Remove the cpu_online() check, and put a BUG_ON(). Quoting Akinobu Mita: Actually the cpu_online() check was necessary before appling this stop_machine: simplify patch. With old __stop_machine_run(), __stop_machine_run() could succeed (return !IS_ERR(p) value) even if take_cpu_down() returned non-zero value. The return value of take_cpu_down() was obtained through kthread_stop().. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: "Akinobu Mita" <akinobu.mita@gmail.com>
| * Simplify stop_machineRusty Russell2008-07-281-10/+3
| | | | | | | | | | | | | | | | | | | | stop_machine creates a kthread which creates kernel threads. We can create those threads directly and simplify things a little. Some care must be taken with CPU hotunplug, which has special needs, but that code seems more robust than it was in the past. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
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