kernel: delete __cpuinit usage from all core kernel files

The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

This removes all the uses of the __cpuinit macros from C files in
the core kernel directories (kernel, init, lib, mm, and include)
that don't really have a specific maintainer.

[1] https://lkml.org/lkml/2013/5/20/589

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
rcu: delete __cpuinit usage from all rcu files

The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

This removes all the drivers/rcu uses of the __cpuinit macros
from all C files.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@freedesktop.org>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
drivers: delete __cpuinit usage from all remaining drivers files

The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

This removes all the remaining one-off uses of the __cpuinit macros
from all C files in the drivers/* directory.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
sched: Fix some kernel-doc warnings

When building the htmldocs (in verbose mode), scripts/kernel-doc
reports the follwing type of warnings:

  Warning(kernel/sched/core.c:936): No description found for return value of 'task_curr'
  ...

Fix those by:

 - adding the missing descriptions
 - using "Return" sections for the descriptions

Signed-off-by: Yacine Belkadi <yacine.belkadi.1@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1373654747-2389-1-git-send-email-yacine.belkadi.1@gmail.com
[ While at it, fix the cpupri_set() explanation. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched: fix the theoretical signal_wake_up() vs schedule() race

This is only theoretical, but after try_to_wake_up(p) was changed
to check p->state under p->pi_lock the code like

	__set_current_state(TASK_INTERRUPTIBLE);
	schedule();

can miss a signal. This is the special case of wait-for-condition,
it relies on try_to_wake_up/schedule interaction and thus it does
not need mb() between __set_current_state() and if(signal_pending).

However, this __set_current_state() can move into the critical
section protected by rq->lock, now that try_to_wake_up() takes
another lock we need to ensure that it can't be reordered with
"if (signal_pending(current))" check inside that section.

The patch is actually one-liner, it simply adds smp_wmb() before
spin_lock_irq(rq->lock). This is what try_to_wake_up() already
does by the same reason.

We turn this wmb() into the new helper, smp_mb__before_spinlock(),
for better documentation and to allow the architectures to change
the default implementation.

While at it, kill smp_mb__after_lock(), it has no callers.

Perhaps we can also add smp_mb__before/after_spinunlock() for
prepare_to_wait().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cpu: Do not return errors from cpu_dev_init() which will be ignored

cpu_dev_init() is only called from driver_init(), which does not check
its return value.  Therefore make cpu_dev_init() return void.

We must register the CPU subsystem, so panic if this fails.

If sched_create_sysfs_power_savings_entries() fails, the damage is
contained, so ignore this (as before).

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 cpu: Register a generic CPU device on architectures that currently do.

. not

frv, h8300, m68k, microblaze, openrisc, score, um and xtensa currently
do not register a CPU device.  Add the config option GENERIC_CPU_DEVICES
which causes a generic CPU device to be registered for each present CPU,
and make all these architectures select it.

Richard Weinberger <richard@nod.at> covered UML and suggested using
per_cpu.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 CPU: Introduce ARCH_HAS_CPU_AUTOPROBE and X86 parts

This patch is based on Andi Kleen's work:
Implement autoprobing/loading of modules serving CPU
specific features (x86cpu autoloading).

And Kay Siever's work to get rid of sysdev cpu structures
and making use of struct device instead.

Before, the cpuid driver had to be loaded to get the x86cpu
autoloading feature. With this patch autoloading works through
the /sys/devices/system/cpu object

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
driver core: cpu: remove kernel warning when removing a cpu

With the movement of the cpu sysdev code to be real stuct devices, now
when we remove a cpu from the system, the driver core rightfully
complains that there is not a release method for this device.

For now, paper over this issue by quieting the driver core, but comment
this in detail.  This will be resolved in future kernels to be solved
properly.

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
driver-core: cpu: fix kobject warning when hotplugging a cpu

Due to the sysdev conversion to struct device, the cpu objects get
reused when adding a cpu after offlining it, which causes a big warning
that the kobject portion is not properly initialized.

So clear out the object before we register it again, so all is quiet.

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/base/cpu.c: Fix typo in comment

[ We should make fun of people who can't speel too, but then we'd have
  no time for any real work at all  - Linus ]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sysfs: Add crash_notes_size to export percpu note size

For percpu notes, we are exporting only address and not size. So
the userspace tool kexec-tools is putting an upper limit of 1024
and putting the value in p_memsz and p_filesz fields. So the patch
add the new sysfile crash_notes_size to export the exact percpu
note size and let the kexec-tools parse it intead of using 1024.

The idea came from Vivek Goyal. And a later patch will be sent to
kexec-tools to let it parse the size.

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sysfs: fix crash_notes_size build warning

commit eca4549f57 "sysfs: Add crash_notes_size to export percpu
note size" adds a printk that outputs a size_t value as %lu
when it should be %zu, resulting in this warning.

drivers/base/cpu.c: In function 'show_crash_notes_size':
drivers/base/cpu.c:142:2: warning: format '%lu' expects argument of type 'long unsigned int', but argument 3 has type 'unsigned int' [-Wformat=]

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Simon Horman <horms@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
numa, cpu hotplug: change links of CPU and node when changing node number by onlining CPU

When booting x86 system contains memoryless node, node numbers of CPUs
on memoryless node were changed to nearest online node number by
init_cpu_to_node() because the node is not online.

In my system, node numbers of cpu#30-44 and 75-89 were changed from 2 to
0 as follows:

  $ numactl --hardware
  available: 2 nodes (0-1)
  node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 30 31 32 33 34 35 36 37 38 39 40
  41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 75 76 77 78 79 80 81 82
  83 84 85 86 87 88 89
  node 0 size: 32394 MB
  node 0 free: 27898 MB
  node 1 cpus: 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 60 61 62 63 64 65 66
  67 68 69 70 71 72 73 74
  node 1 size: 32768 MB
  node 1 free: 30335 MB

If we hot add memory to memoryless node and offine/online all CPUs on
the node, node numbers of these CPUs are changed to correct node numbers
by srat_detect_node() because the node become online.

In this case, node numbers of cpu#30-44 and 75-89 were changed from 0 to
2 in my system as follows:

  $ numactl --hardware
  available: 3 nodes (0-2)
  node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 45 46 47 48 49 50 51 52 53 54 55
  56 57 58 59
  node 0 size: 32394 MB
  node 0 free: 27218 MB
  node 1 cpus: 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 60 61 62 63 64 65 66
  67 68 69 70 71 72 73 74
  node 1 size: 32768 MB
  node 1 free: 30014 MB
  node 2 cpus: 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 75 76 77 78 79 80 81
  82 83 84 85 86 87 88 89
  node 2 size: 16384 MB
  node 2 free: 16384 MB

But "cpu to node" and "node to cpu" links were not changed as follows:

  $ ls /sys/devices/system/cpu/cpu30/|grep node
  node0
  $ ls /sys/devices/system/node/node0/|grep cpu30
  cpu30

"numactl --hardware" shows that cpu30 belongs to node 2.  But sysfs
links does not change.

This patch changes "cpu to node" and "node to cpu" links when node
number changed by onlining CPU.

Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Driver core: Add offline/online device operations

In some cases, graceful hot-removal of devices is not possible,
although in principle the devices in question support hotplug.
For example, that may happen for the last CPU in the system or
for memory modules holding kernel memory.

In those cases it is nice to be able to check if the given device
can be gracefully hot-removed before triggering a removal procedure
that cannot be aborted or reversed.  Unfortunately, however, the
kernel currently doesn't provide any support for that.

To address that deficiency, introduce support for offline and
online operations that can be performed on devices, respectively,
before a hot-removal and in case when it is necessary (or convenient)
to put a device back online after a successful offline (that has not
been followed by removal).  The idea is that the offline will fail
whenever the given device cannot be gracefully removed from the
system and it will not be allowed to use the device after a
successful offline (until a subsequent online) in analogy with the
existing CPU offline/online mechanism.

For now, the offline and online operations are introduced at the
bus type level, as that should be sufficient for the most urgent use
cases (CPUs and memory modules).  In the future, however, the
approach may be extended to cover some more complicated device
offline/online scenarios involving device drivers etc.

The lock_device_hotplug() and unlock_device_hotplug() functions are
introduced because subsequent patches need to put larger pieces of
code under device_hotplug_lock to prevent race conditions between
device offline and removal from happening.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Driver core: Use generic offline/online for CPU offline/online

Rework the CPU hotplug code in drivers/base/cpu.c to use the
generic offline/online support introduced previously instead of
its own CPU-specific code.

For this purpose, modify cpu_subsys to provide offline and online
callbacks for CONFIG_HOTPLUG_CPU set and remove the code handling
the CPU-specific 'online' sysfs attribute.

This modification is not supposed to change the user-observable
behavior of the kernel (i.e. the 'online' attribute will be present
in exactly the same place in sysfs and should trigger exactly the
same actions as before).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
ACPI / processor: Use common hotplug infrastructure

Split the ACPI processor driver into two parts, one that is
non-modular, resides in the ACPI core and handles the enumeration
and hotplug of processors and one that implements the rest of the
existing processor driver functionality.

The non-modular part uses an ACPI scan handler object to enumerate
processors on the basis of information provided by the ACPI namespace
and to hook up with the common ACPI hotplug infrastructure.  It also
populates the ACPI handle of each processor device having a
corresponding object in the ACPI namespace, which allows the driver
proper to bind to those devices, and makes the driver bind to them
if it is readily available (i.e. loaded) when the scan handler's
.attach() routine is running.

There are a few reasons to make this change.

First, switching the ACPI processor driver to using the common ACPI
hotplug infrastructure reduces code duplication and size considerably,
even though a new file is created along with a header comment etc.

Second, since the common hotplug code attempts to offline devices
before starting the (non-reversible) removal procedure, it will abort
(and possibly roll back) hot-remove operations involving processors
if cpu_down() returns an error code for one of them instead of
continuing them blindly (if /sys/firmware/acpi/hotplug/force_remove
is unset).  That is a more desirable behavior than what the current
code does.

Finally, the separation of the scan/hotplug part from the driver
proper makes it possible to simplify the driver's .remove() routine,
because it doesn't need to worry about the possible cleanup related
to processor removal any more (the scan/hotplug part is responsible
for that now) and can handle device removal and driver removal
symmetricaly (i.e. as appropriate).

Some user-visible changes in sysfs are made (for example, the
'sysdev' link from the ACPI device node to the processor device's
directory is gone and a 'physical_node' link is present instead
and a corresponding 'firmware_node' is present in the processor
device's directory, the processor driver is now visible under
/sys/bus/cpu/drivers/ and bound to the processor device), but
that shouldn't affect the functionality that users care about
(frequency scaling, C-states and thermal management).

Tested on my venerable Toshiba Portege R500.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
cpu: fix "crash_notes" and "crash_notes_size" leaks in register_cpu()

"crash_notes" and "crash_notes_size" are dynamically created
with device_create_file() but aren't deleted anywhere.
Define "crash_notes" and "crash_notes_size" statically via
attribute groups so that device_register would create them
automatically and files would be destroyed when CPU is destroyed.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cpu: make sure that cpu/online file created before KOBJ_ADD is emitted

It fixes race between udev and hotplugged CPU registration by defining
"online" attribute statically, so that device_add() would create it
before notifying udev about new CPU.

Original issue report is at https://lkml.org/lkml/2012/4/30/198
"
> On Mon, Apr 30, 2012 at 11:36:23AM -0400, Konrad Rzeszutek Wilk wrote:
> > Hey Greg,
> >
> > Hoping you can help with some guidance on how to fix this.
> >
> > The issue is with CPU hotplug is that when a CPU goes up
> > it calls 'arch_register_cpu' which eventually calls
> > register_cpu. That function does these two things:
> >
> > 251         error = device_register(&cpu->dev);
> > 252         if (!error && cpu->hotpluggable)
> > 253                 register_cpu_control(cpu);
> >
> > and the device_register creates a nice little SysFS directory:
> >
> > /sys/devices/system/cpu/cpu2/ which at line 251 has the 'add' attribute
> > but no 'online' attribute. udev then tries to echo 1 to the 'online'
> > and it we get:
> > udevd-work[2421]: error opening ATTR{/sys/devices/system/cpu/cpu2/online} for writing: No such file or directory
> >
> > Line 253 creates said 'online' and at that time udev [or the system admin]
> > can write 1 to 'online' and the CPU goes up.
> >
> > So .. any thoughts? Is there some way to inhibit from uevent being sent
> > until line 253 has run?
"

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CPU: Fix sysfs cpu/online of offlined CPUs

As reported by Dave Hansen, sysfs cpu/online shows 1 for
offlined CPUs at boot.

Fix this problem by initializing dev.offline with cpu_online()
when registering a CPU.

References: https://lkml.org/lkml/2013/5/29/403
Reported-and-tested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>