From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758335Ab3AQBnG (ORCPT ); Wed, 16 Jan 2013 20:43:06 -0500 Received: from mail-ie0-f179.google.com ([209.85.223.179]:57349 "EHLO mail-ie0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758298Ab3AQBnB (ORCPT ); Wed, 16 Jan 2013 20:43:01 -0500 From: Tejun Heo To: linux-kernel@vger.kernel.org Cc: Lai Jiangshan , Tejun Heo Subject: [PATCH 05/17] workqueue: introduce WORK_OFFQ_CPU_NONE Date: Wed, 16 Jan 2013 17:42:37 -0800 Message-Id: <1358386969-945-6-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.8.0.2 In-Reply-To: <1358386969-945-1-git-send-email-tj@kernel.org> References: <1358386969-945-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, when a work item is off queue, high bits of its data encodes the last CPU it was on. This is scheduled to be changed to pool ID, which will make it impossible to use WORK_CPU_NONE to indicate no association. This patch limits the number of bits which are used for off-queue cpu number to 31 (so that the max fits in an int) and uses the highest possible value - WORK_OFFQ_CPU_NONE - to indicate no association. Signed-off-by: Tejun Heo --- include/linux/workqueue.h | 10 +++++++++- kernel/workqueue.c | 4 ++-- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index ff68b1d..f8b3576 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -73,13 +73,21 @@ enum { WORK_OFFQ_CANCELING = (1 << WORK_OFFQ_FLAG_BASE), + /* + * When a work item is off queue, its high bits point to the last + * cpu it was on. Cap at 31 bits and use the highest number to + * indicate that no cpu is associated. + */ WORK_OFFQ_FLAG_BITS = 1, WORK_OFFQ_CPU_SHIFT = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS, + WORK_OFFQ_LEFT = BITS_PER_LONG - WORK_OFFQ_CPU_SHIFT, + WORK_OFFQ_CPU_BITS = WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31, + WORK_OFFQ_CPU_NONE = (1LU << WORK_OFFQ_CPU_BITS) - 1, /* convenience constants */ WORK_STRUCT_FLAG_MASK = (1UL << WORK_STRUCT_FLAG_BITS) - 1, WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK, - WORK_STRUCT_NO_CPU = (unsigned long)WORK_CPU_NONE << WORK_OFFQ_CPU_SHIFT, + WORK_STRUCT_NO_CPU = (unsigned long)WORK_OFFQ_CPU_NONE << WORK_OFFQ_CPU_SHIFT, /* bit mask for work_busy() return values */ WORK_BUSY_PENDING = 1 << 0, diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 6e8bad6..9da3db2 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -600,7 +600,7 @@ static struct global_cwq *get_work_gcwq(struct work_struct *work) (data & WORK_STRUCT_WQ_DATA_MASK))->pool->gcwq; cpu = data >> WORK_OFFQ_CPU_SHIFT; - if (cpu == WORK_CPU_NONE) + if (cpu == WORK_OFFQ_CPU_NONE) return NULL; BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); @@ -610,7 +610,7 @@ static struct global_cwq *get_work_gcwq(struct work_struct *work) static void mark_work_canceling(struct work_struct *work) { struct global_cwq *gcwq = get_work_gcwq(work); - unsigned long cpu = gcwq ? gcwq->cpu : WORK_CPU_NONE; + unsigned long cpu = gcwq ? gcwq->cpu : WORK_OFFQ_CPU_NONE; set_work_data(work, (cpu << WORK_OFFQ_CPU_SHIFT) | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); -- 1.8.0.2