From: Tejun Heo Date: Sat, 28 Jun 2014 12:10:12 +0000 (-0400) Subject: percpu-refcount: one bit is enough for REF_STATUS X-Git-Tag: omap-for-v3.17/fixes-against-rc2~191^2~4 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=d630dc4c9adb41e5bd1e06df2dbeaf622469ddd5 percpu-refcount: one bit is enough for REF_STATUS 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 Cc: Kent Overstreet Cc: Christoph Lameter --- diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h index 5d8920e23073..bfdeb0d48e21 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 -#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 963b7034a51b..17bce2bccc14 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);