Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933055AbaFRBIP (ORCPT ); Tue, 17 Jun 2014 21:08:15 -0400 Received: from mail-qc0-f179.google.com ([209.85.216.179]:57156 "EHLO mail-qc0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932704AbaFRBIN (ORCPT ); Tue, 17 Jun 2014 21:08:13 -0400 From: Tejun Heo To: cl@linux-foundation.org, kmo@daterainc.com Cc: linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 2/6] percpu-refcount: one bit is enough for REF_STATUS Date: Tue, 17 Jun 2014 21:08:01 -0400 Message-Id: <1403053685-28240-3-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1403053685-28240-1-git-send-email-tj@kernel.org> References: <1403053685-28240-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 -#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); -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/