path: root/kernel/cpu.c
AgeCommit message (Collapse)Author
2007-02-11[PATCH] swsusp: Change code ordering in disk.cRafael J. Wysocki
Change the ordering of code in kernel/power/disk.c so that device_suspend() is called before disable_nonboot_cpus() and platform_finish() is called after enable_nonboot_cpus() and before device_resume(), as indicated by the recent discussion on Linux-PM (cf. The changes here only affect the built-in swsusp. [ fix LED blinking during image load] Signed-off-by: Rafael J. Wysocki <> Acked-by: Pavel Machek <> Cc: Greg KH <> Cc: Nigel Cunningham <> Cc: Patrick Mochel <> Cc: Alexey Starikovskiy <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2007-01-11[PATCH] Change cpu_up and co from __devinit to __cpuinitGautham R Shenoy
Compiling the kernel with CONFIG_HOTPLUG = y and CONFIG_HOTPLUG_CPU = n with CONFIG_RELOCATABLE = y generates the following modpost warnings WARNING: vmlinux - Section mismatch: reference to from .text between '_cpu_up' (at offset 0xc0141b7d) and 'cpu_up' WARNING: vmlinux - Section mismatch: reference to from .text between '_cpu_up' (at offset 0xc0141b9c) and 'cpu_up' WARNING: vmlinux - Section mismatch: reference to .init.text:__cpu_up from .text between '_cpu_up' (at offset 0xc0141bd8) and 'cpu_up' WARNING: vmlinux - Section mismatch: reference to from .text between '_cpu_up' (at offset 0xc0141c05) and 'cpu_up' WARNING: vmlinux - Section mismatch: reference to from .text between '_cpu_up' (at offset 0xc0141c26) and 'cpu_up' WARNING: vmlinux - Section mismatch: reference to from .text between '_cpu_up' (at offset 0xc0141c37) and 'cpu_up' This is because cpu_up, _cpu_up and __cpu_up (in some architectures) are defined as __devinit AND __cpu_up calls some __cpuinit functions. Since __cpuinit would map to __init with this kind of a configuration, we get a .text refering warning. This patch solves the problem by converting all of __cpu_up, _cpu_up and cpu_up from __devinit to __cpuinit. The approach is justified since the callers of cpu_up are either dependent on CONFIG_HOTPLUG_CPU or are of __init type. Thus when CONFIG_HOTPLUG_CPU=y, all these cpu up functions would land up in .text section, and when CONFIG_HOTPLUG_CPU=n, all these functions would land up in .init section. Tested on a i386 SMP machine running linux-2.6.20-rc3-mm1. Signed-off-by: Gautham R Shenoy <> Cc: Vivek Goyal <> Cc: Mikael Starvik <> Cc: Ralf Baechle <> Cc: Kyle McMartin <> Cc: Paul Mackerras <> Cc: Benjamin Herrenschmidt <> Cc: "David S. Miller" <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2006-12-23[PATCH] suspend: fix suspend on single-CPU systemsIngo Molnar
Clark Williams reported that suspend doesnt work on his laptop on 2.6.20-rc1-rt kernels. The bug was introduced by the following cleanup commit: commit 112cecb2cc0e7341db92281ba04b26c41bb8146d Author: Siddha, Suresh B <> Date: Wed Dec 6 20:34:31 2006 -0800 [PATCH] suspend: don't change cpus_allowed for task initiating the suspend because with this change 'error' is not initialized to 0 anymore, if there are no other online CPUs. (i.e. if the system is single-CPU). the fix is the initialize it to 0. The really weird thing is that my version of gcc does not warn about this non-initialized variable situation ... (also fix the kernel printk in the error branch, it was missing a newline) Reported-by: Clark Williams <> Signed-off-by: Ingo Molnar <> Signed-off-by: Linus Torvalds <>
2006-12-07[PATCH] suspend: don't change cpus_allowed for task initiating the suspendSiddha, Suresh B
Don't modify the cpus_allowed of the task initiating the suspend. _cpu_down() already makes sure that the task doing the suspend doesn't run on dying cpu. Signed-off-by: Suresh Siddha <> Cc: Venkatesh Pallipadi <> Cc: Pavel Machek <> Cc: "Rafael J. Wysocki" <> Cc: Nigel Cunningham <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2006-11-06[PATCH] Fix the spurious unlock_cpu_hotplug false warningsGautham R Shenoy
Cpu-hotplug locking has a minor race case caused because of setting the variable "recursive" to NULL *after* releasing the cpu_bitmask_lock in the function unlock_cpu_hotplug,instead of doing so before releasing the cpu_bitmask_lock. This was the cause of most of the recent false spurious lock_cpu_unlock warnings. This should fix the problem reported by Martin Lorenz reported in Thanks to Srinivasa DS for pointing it out. Signed-off-by: Gautham R Shenoy <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2006-10-28[PATCH] cpu-hotplug: release `workqueue_mutex' properly on CPU hot-removeSatoru Takeuchi
_cpu_down() acquires `workqueue_mutex' on its process, but doen't release it if __cpu_disable() fails. Signed-off-by: Satoru Takeuchi <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2006-10-17[PATCH] Convert cpu hotplug notifiers to use raw_notifier instead of ↵Neil Brown
blocking_notifier The use of blocking notifier by _cpu_up and _cpu_down in cpu.c has two problem. 1/ An interaction with the workqueue notifier causes lockdep to spit a warning. 2/ A notifier could conceivable be added or removed while _cpu_up or _cpu_down are in process. As each notifier is called twice (prepare then commit/abort) this could be unhealthy. To fix to we simply take cpu_add_remove_lock while adding or removing notifiers to/from the list. This makes the 'blocking' usage unnecessary as all accesses to cpu_chain are now protected by cpu_add_remove_lock. So change "blocking" to "raw" in all relevant places. This fixes 1. Credit: Andrew Morton Cc: Rusty Russell <> Cc: Michal Piotrowski <> (reporter) Signed-off-by: Neil Brown <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2006-09-26[PATCH] Disable CPU hotplug during suspendRafael J. Wysocki
The current suspend code has to be run on one CPU, so we use the CPU hotplug to take the non-boot CPUs offline on SMP machines. However, we should also make sure that these CPUs will not be enabled by someone else after we have disabled them. The functions disable_nonboot_cpus() and enable_nonboot_cpus() are moved to kernel/cpu.c, because they now refer to some stuff in there that should better be static. Also it's better if disable_nonboot_cpus() returns an error instead of panicking if something goes wrong, and enable_nonboot_cpus() has no reason to panic(), because the CPUs may have been enabled by the userland before it tries to take them online. Signed-off-by: Rafael J. Wysocki <> Acked-by: Pavel Machek <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2006-07-23cpu hotplug: simplify and hopefully fix lockingLinus Torvalds
The CPU hotplug locking was quite messy, with a recursive lock to handle the fact that both the actual up/down sequence wanted to protect itself from being re-entered, but the callbacks that it called also tended to want to protect themselves from CPU events. This splits the lock into two (one to serialize the whole hotplug sequence, the other to protect against the CPU present bitmaps changing). The latter still allows recursive usage because some subsystems (ondemand policy for cpufreq at least) had already gotten too used to the lax locking, but the locking mistakes are hopefully now less fundamental, and we now warn about recursive lock usage when we see it, in the hope that it can be fixed. Signed-off-by: Linus Torvalds <>
2006-06-27[PATCH] cpu hotplug: make [un]register_cpu_notifier init time onlyChandra Seetharaman
CPUs come online only at init time (unless CONFIG_HOTPLUG_CPU is defined). So, cpu_notifier functionality need to be available only at init time. This patch makes register_cpu_notifier() available only at init time, unless CONFIG_HOTPLUG_CPU is defined. This patch exports register_cpu_notifier() and unregister_cpu_notifier() only if CONFIG_HOTPLUG_CPU is defined. Signed-off-by: Chandra Seetharaman <> Cc: Ashok Raj <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2006-06-26[PATCH] Convert kernel/cpu.c to mutexesIngo Molnar
Convert kernel/cpu.c from semaphore to mutex. I've reviewed all lock_cpu_hotplug() critical sections, and they all seem to fit mutex semantics. Signed-off-by: Ingo Molnar <> Cc: Rusty Russell <> Cc: Ashok Raj <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2006-03-27[PATCH] Notifier chain update: API changesAlan Stern
The kernel's implementation of notifier chains is unsafe. There is no protection against entries being added to or removed from a chain while the chain is in use. The issues were discussed in this thread: We noticed that notifier chains in the kernel fall into two basic usage classes: "Blocking" chains are always called from a process context and the callout routines are allowed to sleep; "Atomic" chains can be called from an atomic context and the callout routines are not allowed to sleep. We decided to codify this distinction and make it part of the API. Therefore this set of patches introduces three new, parallel APIs: one for blocking notifiers, one for atomic notifiers, and one for "raw" notifiers (which is really just the old API under a new name). New kinds of data structures are used for the heads of the chains, and new routines are defined for registration, unregistration, and calling a chain. The three APIs are explained in include/linux/notifier.h and their implementation is in kernel/sys.c. With atomic and blocking chains, the implementation guarantees that the chain links will not be corrupted and that chain callers will not get messed up by entries being added or removed. For raw chains the implementation provides no guarantees at all; users of this API must provide their own protections. (The idea was that situations may come up where the assumptions of the atomic and blocking APIs are not appropriate, so it should be possible for users to handle these things in their own way.) There are some limitations, which should not be too hard to live with. For atomic/blocking chains, registration and unregistration must always be done in a process context since the chain is protected by a mutex/rwsem. Also, a callout routine for a non-raw chain must not try to register or unregister entries on its own chain. (This did happen in a couple of places and the code had to be changed to avoid it.) Since atomic chains may be called from within an NMI handler, they cannot use spinlocks for synchronization. Instead we use RCU. The overhead falls almost entirely in the unregister routine, which is okay since unregistration is much less frequent that calling a chain. Here is the list of chains that we adjusted and their classifications. None of them use the raw API, so for the moment it is only a placeholder. ATOMIC CHAINS ------------- arch/i386/kernel/traps.c: i386die_chain arch/ia64/kernel/traps.c: ia64die_chain arch/powerpc/kernel/traps.c: powerpc_die_chain arch/sparc64/kernel/traps.c: sparc64die_chain arch/x86_64/kernel/traps.c: die_chain drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list kernel/panic.c: panic_notifier_list kernel/profile.c: task_free_notifier net/bluetooth/hci_core.c: hci_notifier net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain net/ipv6/addrconf.c: inet6addr_chain net/netfilter/nf_conntrack_core.c: nf_conntrack_chain net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain net/netlink/af_netlink.c: netlink_chain BLOCKING CHAINS --------------- arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain arch/s390/kernel/process.c: idle_chain arch/x86_64/kernel/process.c idle_notifier drivers/base/memory.c: memory_chain drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list drivers/macintosh/adb.c: adb_client_list drivers/macintosh/via-pmu.c sleep_notifier_list drivers/macintosh/via-pmu68k.c sleep_notifier_list drivers/macintosh/windfarm_core.c wf_client_list drivers/usb/core/notify.c usb_notifier_list drivers/video/fbmem.c fb_notifier_list kernel/cpu.c cpu_chain kernel/module.c module_notify_list kernel/profile.c munmap_notifier kernel/profile.c task_exit_notifier kernel/sys.c reboot_notifier_list net/core/dev.c netdev_chain net/decnet/dn_dev.c: dnaddr_chain net/ipv4/devinet.c: inetaddr_chain It's possible that some of these classifications are wrong. If they are, please let us know or submit a patch to fix them. Note that any chain that gets called very frequently should be atomic, because the rwsem read-locking used for blocking chains is very likely to incur cache misses on SMP systems. (However, if the chain's callout routines may sleep then the chain cannot be atomic.) The patch set was written by Alan Stern and Chandra Seetharaman, incorporating material written by Keith Owens and suggestions from Paul McKenney and Andrew Morton. [ restructure the notifier chain initialization macros] Signed-off-by: Alan Stern <> Signed-off-by: Chandra Seetharaman <> Signed-off-by: Jes Sorensen <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2006-03-24BUG_ON() Conversion in kernel/cpu.cEric Sesterhenn
this changes if() BUG(); constructs to BUG_ON() which is cleaner, contains unlikely() and can better optimized away. Signed-off-by: Eric Sesterhenn <> Signed-off-by: Adrian Bunk <>
2005-11-28[PATCH] clean up lock_cpu_hotplug() in cpufreqAshok Raj
There are some callers in cpufreq hotplug notify path that the lowest function calls lock_cpu_hotplug(). The lock is already held during cpu_up() and cpu_down() calls when the notify calls are broadcast to registered clients. Ideally if possible, we could disable_preempt() at the highest caller and make sure we dont sleep in the path down in cpufreq->driver_target() calls but the calls are so intertwined and cumbersome to cleanup. Hence we consistently use lock_cpu_hotplug() and unlock_cpu_hotplug() in all places. - Removed export of cpucontrol semaphore and made it static. - removed explicit uses of up/down with lock_cpu_hotplug() so we can keep track of the the callers in same thread context and just keep refcounts without calling a down() that causes a deadlock. - Removed current_in_hotplug() uses - Removed PF_HOTPLUG_CPU in sched.h introduced for the current_in_hotplug() temporary workaround. Tested with insmod of cpufreq_stat.ko, and logical online/offline to make sure we dont have any hang situations. Signed-off-by: Ashok Raj <> Cc: Zwane Mwaikambo <> Cc: Shaohua Li <> Cc: "Siddha, Suresh B" <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2005-11-09[PATCH] cpu hotplug: fix locking in cpufreq driversAshok Raj
When calling target drivers to set frequency, we take cpucontrol lock. When we modified the code to accomodate CPU hotplug, there was an attempt to take a double lock of cpucontrol leading to a deadlock. Since the current thread context is already holding the cpucontrol lock, we dont need to make another attempt to acquire it. Now we leave a trace in current->flags indicating current thread already is under cpucontrol lock held, so we dont attempt to do this another time. Thanks to Andrew Morton for the beating:-) From: Brice Goglin <> Build fix (akpm: this patch is still unpleasant. Ashok continues to look for a cleaner solution, doesn't he? ;)) Signed-off-by: Ashok Raj <> Signed-off-by: Brice Goglin <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2005-10-30[PATCH] create and destroy cpufreq sysfs entries based on cpu notifiersAshok Raj
cpufreq entries in sysfs should only be populated when CPU is online state. When we either boot with maxcpus=x and then boot the other cpus by echoing to sysfs online file, these entries should be created and destroyed when CPU_DEAD is notified. Same treatement as cache entries under sysfs. We place the processor in the lowest frequency, so hw managed P-State transitions can still work on the other threads to save power. Primary goal was to just make these directories appear/disapper dynamically. There is one in this patch i had to do, which i really dont like myself but probably best if someone handling the cpufreq infrastructure could give this code right treatment if this is not acceptable. I guess its probably good for the first cut. - Converting lock_cpu_hotplug()/unlock_cpu_hotplug() to disable/enable preempt. The locking was smack in the middle of the notification path, when the hotplug is already holding the lock. I tried another solution to avoid this so avoid taking locks if we know we are from notification path. The solution was getting very ugly and i decided this was probably good for this iteration until someone who understands cpufreq could do a better job than me. (akpm: export cpucontrol to GPL modules: drivers/cpufreq/cpufreq_stats.c now does lock_cpu_hotplug()) Signed-off-by: Ashok Raj <> Signed-off-by: Venkatesh Pallipadi <> Cc: Dave Jones <> Cc: Zwane Mwaikambo <> Cc: Greg KH <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2005-06-25[PATCH] i386 CPU hotplugZwane Mwaikambo
(The i386 CPU hotplug patch provides infrastructure for some work which Pavel is doing as well as for ACPI S3 (suspend-to-RAM) work which Li Shaohua <> is doing) The following provides i386 architecture support for safely unregistering and registering processors during runtime, updated for the current -mm tree. In order to avoid dumping cpu hotplug code into kernel/irq/* i dropped the cpu_online check in do_IRQ() by modifying fixup_irqs(). The difference being that on cpu offline, fixup_irqs() is called before we clear the cpu from cpu_online_map and a long delay in order to ensure that we never have any queued external interrupts on the APICs. There are additional changes to s390 and ppc64 to account for this change. 1) Add CONFIG_HOTPLUG_CPU 2) disable local APIC timer on dead cpus. 3) Disable preempt around irq balancing to prevent CPUs going down. 4) Print irq stats for all possible cpus. 5) Debugging check for interrupts on offline cpus. 6) Hacky fixup_irqs() to redirect irqs when cpus go off/online. 7) play_dead() for offline cpus to spin inside. 8) Handle offline cpus set in flush_tlb_others(). 9) Grab lock earlier in smp_call_function() to prevent CPUs going down. 10) Implement __cpu_disable() and __cpu_die(). 11) Enable local interrupts in cpu_enable() after fixup_irqs() 12) Don't fiddle with NMI on dead cpu, but leave intact on other cpus. 13) Program IRQ affinity whilst cpu is still in cpu_online_map on offline. Signed-off-by: Zwane Mwaikambo <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2005-04-16Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!