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Merge branch 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu into for-3.16

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Pull to receive percpu_ref_tryget[_live]() changes.  Planned cgroup
changes will make use of them.

Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2014-05-13 11:27:24 -04:00
commit d39ea871c3
3 changed files with 35 additions and 3 deletions
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2
include/linux/cgroup.h
View file

@ -108,7 +108,7 @@ static inline bool css_tryget(struct cgroup_subsys_state *css)
{ {
if (css->flags & CSS_ROOT) if (css->flags & CSS_ROOT)
return true; return true;
return percpu_ref_tryget(&css->refcnt); return percpu_ref_tryget_live(&css->refcnt);
} }
/** /**

34
include/linux/percpu-refcount.h
View file

@ -121,6 +121,36 @@ static inline void percpu_ref_get(struct percpu_ref *ref)
* percpu_ref_tryget - try to increment a percpu refcount * percpu_ref_tryget - try to increment a percpu refcount
* @ref: percpu_ref to try-get * @ref: percpu_ref to try-get
* *
* Increment a percpu refcount unless its count already reached zero.
* Returns %true on success; %false on failure.
*
* The caller is responsible for ensuring that @ref stays accessible.
*/
static inline bool percpu_ref_tryget(struct percpu_ref *ref)
{
unsigned __percpu *pcpu_count;
int ret = false;
rcu_read_lock_sched();
pcpu_count = ACCESS_ONCE(ref->pcpu_count);
if (likely(REF_STATUS(pcpu_count) == PCPU_REF_PTR)) {
__this_cpu_inc(*pcpu_count);
ret = true;
} else {
ret = atomic_inc_not_zero(&ref->count);
}
rcu_read_unlock_sched();
return ret;
}
/**
* percpu_ref_tryget_live - try to increment a live percpu refcount
* @ref: percpu_ref to try-get
*
* Increment a percpu refcount unless it has already been killed. Returns * Increment a percpu refcount unless it has already been killed. Returns
* %true on success; %false on failure. * %true on success; %false on failure.
* *
@ -128,8 +158,10 @@ static inline void percpu_ref_get(struct percpu_ref *ref)
* will fail. For such guarantee, percpu_ref_kill_and_confirm() should be * will fail. For such guarantee, percpu_ref_kill_and_confirm() should be
* used. After the confirm_kill callback is invoked, it's guaranteed that * used. After the confirm_kill callback is invoked, it's guaranteed that
* no new reference will be given out by percpu_ref_tryget(). * no new reference will be given out by percpu_ref_tryget().
*
* The caller is responsible for ensuring that @ref stays accessible.
*/ */
static inline bool percpu_ref_tryget(struct percpu_ref *ref) static inline bool percpu_ref_tryget_live(struct percpu_ref *ref)
{ {
unsigned __percpu *pcpu_count; unsigned __percpu *pcpu_count;
int ret = false; int ret = false;

2
include/linux/percpu.h
View file

@ -29,7 +29,7 @@
*/ */
#define get_cpu_var(var) (*({ \ #define get_cpu_var(var) (*({ \
preempt_disable(); \ preempt_disable(); \
&__get_cpu_var(var); })) this_cpu_ptr(&var); }))
/* /*
* The weird & is necessary because sparse considers (void)(var) to be * The weird & is necessary because sparse considers (void)(var) to be