From 715b06b864c99a18cb8368dfb187da4f569788cd Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 24 Jan 2013 11:01:33 -0800 Subject: [PATCH] workqueue: introduce WORK_OFFQ_CPU_NONE 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 Reviewed-by: Lai Jiangshan --- 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 ff68b1d95b41..f8b35763e55f 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 1a686e481132..405282d30046 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -573,7 +573,7 @@ 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); @@ -583,7 +583,7 @@ 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); -- 2.39.2