On 06/18/2014 09:08 AM, Tejun Heo wrote: > percpu-refcount currently reserves two lowest bits of its percpu > pointer to indicate its state; however, only one bit is used for > PCPU_REF_DEAD. > > Simplify it by removing PCPU_STATUS_BITS/MASK and testing > PCPU_REF_DEAD directly. This also allows the compiler to choose a > more efficient instruction depending on the architecture. > > Signed-off-by: Tejun Heo <t...@kernel.org> > Cc: Kent Overstreet <k...@daterainc.com> > Cc: Christoph Lameter <c...@linux-foundation.org> > --- > include/linux/percpu-refcount.h | 4 +--- > lib/percpu-refcount.c | 2 +- > 2 files changed, 2 insertions(+), 4 deletions(-) > > diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h > index 5d8920e..bfdeb0d4 100644 > --- a/include/linux/percpu-refcount.h > +++ b/include/linux/percpu-refcount.h > @@ -88,12 +88,10 @@ static inline void percpu_ref_kill(struct percpu_ref *ref) > return percpu_ref_kill_and_confirm(ref, NULL); > } > > -#define PCPU_STATUS_BITS 2
Just using "#define PCPU_STATUS_BITS 1" can achieve exactly the same result as you need. And it is better for future extensions for the status. Anyway, Reviewed-by: Lai Jiangshan <la...@cn.fujitsu.com> > -#define PCPU_STATUS_MASK ((1 << PCPU_STATUS_BITS) - 1) > #define PCPU_REF_PTR 0 > #define PCPU_REF_DEAD 1 > > -#define REF_STATUS(count) (((unsigned long) count) & PCPU_STATUS_MASK) > +#define REF_STATUS(count) (((unsigned long) count) & PCPU_REF_DEAD) > > /** > * percpu_ref_get - increment a percpu refcount > diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c > index 963b703..17bce2b 100644 > --- a/lib/percpu-refcount.c > +++ b/lib/percpu-refcount.c > @@ -96,7 +96,7 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu) > > /* Mask out PCPU_REF_DEAD */ > pcpu_count = (unsigned __percpu *) > - (((unsigned long) pcpu_count) & ~PCPU_STATUS_MASK); > + (((unsigned long) pcpu_count) & ~PCPU_REF_DEAD); > > for_each_possible_cpu(cpu) > count += *per_cpu_ptr(pcpu_count, cpu); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
