linux-toradex.git/include/linux/cpumask.h, branch v2.6.36-rc5

cpumask: let num_*_cpus() function always return unsigned values

2010-03-06T19:26:29+00:00

Dependent on CONFIG_SMP the num_*_cpus() functions return unsigned or
signed values.  Let them always return unsigned values to avoid strange
casts.

Fixes at least one warning:

 kernel/kprobes.c: In function 'register_kretprobe':
 kernel/kprobes.c:1038: warning: comparison of distinct pointer types lacks a cast

Signed-off-by: Heiko Carstens 
Cc: Heiko Carstens 
Cc: Ananth N Mavinakayanahalli 
Cc: Masami Hiramatsu 
Cc: Ingo Molnar 
Cc: Rusty Russell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rcu: Accelerate grace period if last non-dynticked CPU

2010-02-25T09:34:55+00:00

Currently, rcu_needs_cpu() simply checks whether the current CPU
has an outstanding RCU callback, which means that the last CPU
to go into dyntick-idle mode might wait a few ticks for the
relevant grace periods to complete.  However, if all the other
CPUs are in dyntick-idle mode, and if this CPU is in a quiescent
state (which it is for RCU-bh and RCU-sched any time that we are
considering going into dyntick-idle mode), then the grace period
is instantly complete.

This patch therefore repeatedly invokes the RCU grace-period
machinery in order to force any needed grace periods to complete
quickly.  It does so a limited number of times in order to
prevent starvation by an RCU callback function that might pass
itself to call_rcu().

However, if any CPU other than the current one is not in
dyntick-idle mode, fall back to simply checking (with fix to bug
noted by Lai Jiangshan).  Also, take advantage of last
grace-period forcing, the opportunity to do so noted by Steve
Rostedt.  And apply simplified #ifdef condition suggested by
Frederic Weisbecker.

Signed-off-by: Paul E. McKenney 
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-15-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar

sched: Fix balance vs hotplug race

2009-12-06T20:10:56+00:00

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 
LKML-Reference: 
Signed-off-by: Ingo Molnar

cpumask: Move deprecated functions to end of header.

2009-09-24T00:04:53+00:00

The new ones have pretty kerneldoc.  Move the old ones to the end to
avoid confusing people.

Signed-off-by: Rusty Russell 
Cc: benh@kernel.crashing.org

cpumask: remove unused deprecated functions, avoid accusations of insanity

2009-09-24T00:04:53+00:00

We're not forcing removal of the old cpu_ functions, but we might as
well delete the now-unused ones.

Especially CPUMASK_ALLOC and friends.  I actually got a phone call (!)
from a hacker who thought I had introduced them as the new cpumask
API.  He seemed bewildered that I had lost all taste.

Signed-off-by: Rusty Russell 
Cc: benh@kernel.crashing.org

cpumask: remove unused cpu_mask_all

2009-09-24T00:04:36+00:00

It's only defined for NR_CPUS > BITS_PER_LONG; cpu_all_mask is always
defined (and const).

Signed-off-by: Rusty Russell

cpumask: remove dangerous CPU_MASK_ALL_PTR

2009-09-24T00:04:35+00:00

(Thanks to Al Viro for reminding me of this, via Ingo)

CPU_MASK_ALL is the (deprecated) "all bits set" cpumask, defined as so:

	#define CPU_MASK_ALL (cpumask_t) { { ... } }

Taking the address of such a temporary is questionable at best,
unfortunately 321a8e9d (cpumask: add CPU_MASK_ALL_PTR macro) added
CPU_MASK_ALL_PTR:

	#define CPU_MASK_ALL_PTR (&CPU_MASK_ALL)

Which formalizes this practice.  One day gcc could bite us over this
usage (though we seem to have gotten away with it so far).

Now all callers are removed, we kill it.

Signed-off-by: Rusty Russell 
Acked-by: Ingo Molnar 
Reported-by: Al Viro 
Cc: Mike Travis

generic-ipi: make struct call_function_data lockless

2009-09-23T14:39:28+00:00

This patch can remove spinlock from struct call_function_data, the
reasons are below:

1: add a new interface for cpumask named cpumask_test_and_clear_cpu(),
   it can atomically test and clear specific cpu, we can use it instead
   of cpumask_test_cpu() and cpumask_clear_cpu() and no need data->lock
   to protect those in generic_smp_call_function_interrupt().

2: in smp_call_function_many(), after csd_lock() return, the current's
   cfd_data is deleted from call_function list, so it not have race
   between other cpus, then cfs_data is only used in
   smp_call_function_many() that must disable preemption and not from
   a hardware interrupthandler or from a bottom half handler to call,
   only the correspond cpu can use it, so it not have race in current
   cpu, no need cfs_data->lock to protect it.

3: after 1 and 2, cfs_data->lock is only use to protect cfs_data->refs in
   generic_smp_call_function_interrupt(), so we can define cfs_data->refs
   to atomic_t, and no need cfs_data->lock any more.

Signed-off-by: Xiao Guangrong 
Cc: Ingo Molnar 
Cc: Jens Axboe 
Cc: Nick Piggin 
Cc: Peter Zijlstra 
Acked-by: Rusty Russell 
[akpm@linux-foundation.org: use atomic_dec_return()]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Make bitmask 'and' operators return a result code

2009-08-21T16:26:15+00:00

When 'and'ing two bitmasks (where 'andnot' is a variation on it), some
cases want to know whether the result is the empty set or not.  In
particular, the TLB IPI sending code wants to do cpumask operations and
determine if there are any CPU's left in the final set.

So this just makes the bitmask (and cpumask) functions return a boolean
for whether the result has any bits set.

Cc: stable@kernel.org (2.6.30, needed by TLB shootdown fix)
Signed-off-by: Linus Torvalds

cpumask: introduce zalloc_cpumask_var

2009-06-09T13:00:26+00:00

So can get cpumask_var with cpumask_clear

Signed-off-by: Yinghai Lu 
Signed-off-by: Rusty Russell