linux.git/arch/sparc/kernel/sysfs.c, branch v4.13

sparc/sysfs: Replace racy task affinity logic

2017-04-15T10:20:54+00:00

The mmustat_enable sysfs file accessor functions must run code on the
target CPU. This is achieved by temporarily setting the affinity of the
calling user space thread to the requested CPU and reset it to the original
affinity afterwards.

That's racy vs. concurrent affinity settings for that thread resulting in
code executing on the wrong CPU and overwriting the new affinity setting.

Replace it by using work_on_cpu() which guarantees to run the code on the
requested CPU.

Protection against CPU hotplug is not required as the open sysfs file
already prevents the removal from the CPU offline callback. Using the
hotplug protected version would actually be wrong because it would deadlock
against a CPU hotplug operation of the CPU associated to the sysfs file in
progress.

Signed-off-by: Thomas Gleixner 
Acked-by: David S. Miller 
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Cc: herbert@gondor.apana.org.au
Cc: rjw@rjwysocki.net
Cc: peterz@infradead.org
Cc: benh@kernel.crashing.org
Cc: bigeasy@linutronix.de
Cc: jiangshanlai@gmail.com
Cc: sparclinux@vger.kernel.org
Cc: viresh.kumar@linaro.org
Cc: mpe@ellerman.id.au
Cc: tj@kernel.org
Cc: lenb@kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1704131001270.2408@nanos
Signed-off-by: Thomas Gleixner

sched/core: Remove the tsk_cpus_allowed() wrapper

2017-03-02T07:42:24+00:00

So the original intention of tsk_cpus_allowed() was to 'future-proof'
the field - but it's pretty ineffectual at that, because half of
the code uses ->cpus_allowed directly ...

Also, the wrapper makes the code longer than the original expression!

So just get rid of it. This also shrinks  a bit.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

sparc/sysfs: Convert to hotplug state machine

2016-11-22T22:34:42+00:00

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

The previous convention of keeping the files around until the CPU is dead
has not been preserved as there is no point to keep them available when the
cpu is going down. This makes the hotplug call symmetric.

Signed-off-by: Sebastian Andrzej Siewior 
Acked-by: "David S. Miller" 
Cc: sparclinux@vger.kernel.org
Cc: rt@linuxtronix.de
Link: http://lkml.kernel.org/r/20161117183541.8588-18-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner

sparc: Fix misspellings in comments.

2016-03-21T04:28:58+00:00

Signed-off-by: Adam Buchbinder 
Reviewed-by: Julian Calaby 
Signed-off-by: David S. Miller

sparc64: fix format string mismatch in arch/sparc/kernel/sysfs.c

2014-05-21T19:54:42+00:00

found by cppcheck

Signed-off-by: Toralf Förster 
Acked-by: Sam Ravnborg 
Signed-off-by: David S. Miller

sparc, sysfs: Fix CPU hotplug callback registration

2014-03-20T12:43:41+00:00

Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:

	get_online_cpus();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	register_cpu_notifier(&foobar_cpu_notifier);

	put_online_cpus();

This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).

Instead, the correct and race-free way of performing the callback
registration is:

	cpu_notifier_register_begin();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	/* Note the use of the double underscored version of the API */
	__register_cpu_notifier(&foobar_cpu_notifier);

	cpu_notifier_register_done();

Fix the sysfs code in sparc by using this latter form of callback
registration.

Cc: Ingo Molnar 
Acked-by: David S. Miller 
Signed-off-by: Srivatsa S. Bhat 
Signed-off-by: Rafael J. Wysocki

sparc: delete cpuinit/CPUINIT usage from all users

2013-07-14T23:36:52+00:00

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.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings.  In any case, they are temporary and harmless.

This removes all the arch/sparc uses of the __cpuinit macros from
C files and removes __CPUINIT from assembly files.  Note that even
though arch/sparc/kernel/trampoline_64.S has instances of ".previous"
in it, they are all paired off against explicit ".section" directives,
and not implicitly paired with __CPUINIT (unlike mips and arm were).

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

Cc: "David S. Miller" 
Cc: sparclinux@vger.kernel.org
Signed-off-by: Paul Gortmaker

cpu: convert 'cpu' and 'machinecheck' sysdev_class to a regular subsystem

2011-12-21T22:29:42+00:00

This moves the 'cpu sysdev_class' over to a regular 'cpu' subsystem
and converts the devices to regular devices. The sysdev drivers are
implemented as subsystem interfaces now.

After all sysdev classes are ported to regular driver core entities, the
sysdev implementation will be entirely removed from the kernel.

Userspace relies on events and generic sysfs subsystem infrastructure
from sysdev devices, which are made available with this conversion.

Cc: Haavard Skinnemoen 
Cc: Hans-Christian Egtvedt 
Cc: Tony Luck 
Cc: Fenghua Yu 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: Paul Mundt 
Cc: "David S. Miller" 
Cc: Chris Metcalf 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: Borislav Petkov 
Cc: Tigran Aivazian 
Cc: Len Brown 
Cc: Zhang Rui 
Cc: Dave Jones 
Cc: Peter Zijlstra 
Cc: Russell King 
Cc: Andrew Morton 
Cc: Arjan van de Ven 
Cc: "Rafael J. Wysocki" 
Cc: "Srivatsa S. Bhat" 
Signed-off-by: Kay Sievers 
Signed-off-by: Greg Kroah-Hartman

sparc: convert old cpumask API into new one

2011-05-16T20:38:07+00:00

Adapt new API. Almost change is trivial, most important change are to
remove following like =operator.

 cpumask_t cpu_mask = *mm_cpumask(mm);
 cpus_allowed = current->cpus_allowed;

Because cpumask_var_t is =operator unsafe. These usage might prevent
kernel core improvement.

No functional change.

Signed-off-by: KOSAKI Motohiro 
Signed-off-by: David S. Miller

arch/sparc/kernel: Use set_cpus_allowed_ptr

2010-03-28T04:11:56+00:00

Use set_cpus_allowed_ptr rather than set_cpus_allowed.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// 
@@
expression E1,E2;
@@

- set_cpus_allowed(E1, cpumask_of_cpu(E2))
+ set_cpus_allowed_ptr(E1, cpumask_of(E2))

@@
expression E;
identifier I;
@@

- set_cpus_allowed(E, I)
+ set_cpus_allowed_ptr(E, &I)
// 

Signed-off-by: Julia Lawall 
Signed-off-by: David S. Miller