From: Tejun Heo <tj@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>, Tejun Heo <tj@kernel.org>
Subject: [PATCH 05/17] workqueue: introduce WORK_OFFQ_CPU_NONE
Date: Wed, 16 Jan 2013 17:42:37 -0800 [thread overview]
Message-ID: <1358386969-945-6-git-send-email-tj@kernel.org> (raw)
In-Reply-To: <1358386969-945-1-git-send-email-tj@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 <tj@kernel.org>
---
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
next prev parent reply other threads:[~2013-01-17 1:43 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-17 1:42 [PATCHSET] workqueue: remove gcwq and make worker_pool the only backend abstraction Tejun Heo
2013-01-17 1:42 ` [PATCH 01/17] workqueue: unexport work_cpu() Tejun Heo
2013-01-17 1:42 ` [PATCH 02/17] workqueue: use std_ prefix for the standard per-cpu pools Tejun Heo
2013-01-17 1:42 ` [PATCH 03/17] workqueue: make GCWQ_DISASSOCIATED a pool flag Tejun Heo
2013-01-17 1:42 ` [PATCH 04/17] workqueue: make GCWQ_FREEZING " Tejun Heo
2013-01-17 1:42 ` Tejun Heo [this message]
2013-01-17 1:42 ` [PATCH 06/17] workqueue: add worker_pool->id Tejun Heo
2013-01-17 1:42 ` [PATCH 07/17] workqueue: record pool ID instead of CPU in work->data when off-queue Tejun Heo
2013-01-17 1:42 ` [PATCH 08/17] workqueue: move busy_hash from global_cwq to worker_pool Tejun Heo
2013-01-17 1:42 ` [PATCH 09/17] workqueue: move global_cwq->cpu " Tejun Heo
2013-01-17 1:42 ` [PATCH 10/17] workqueue: move global_cwq->lock " Tejun Heo
2013-01-17 1:42 ` [PATCH 11/17] workqueue: make hotplug processing per-pool Tejun Heo
2013-01-17 1:42 ` [PATCH 12/17] workqueue: make freezing/thawing per-pool Tejun Heo
2013-01-17 1:42 ` [PATCH 13/17] workqueue: replace for_each_worker_pool() with for_each_std_worker_pool() Tejun Heo
2013-01-17 1:42 ` [PATCH 14/17] workqueue: remove worker_pool->gcwq Tejun Heo
2013-01-17 1:42 ` [PATCH 15/17] workqueue: remove global_cwq Tejun Heo
2013-01-22 6:50 ` Joonsoo Kim
2013-01-23 1:09 ` Tejun Heo
2013-01-23 18:09 ` [PATCH v2 " Tejun Heo
2013-01-24 9:29 ` Joonsoo Kim
2013-01-24 18:44 ` Tejun Heo
2013-01-17 1:42 ` [PATCH 16/17] workqueue: rename nr_running variables Tejun Heo
2013-01-17 1:42 ` [PATCH 17/17] workqueue: post global_cwq removal cleanups Tejun Heo
2013-01-17 1:48 ` [PATCHSET] workqueue: remove gcwq and make worker_pool the only backend abstraction Tejun Heo
2013-01-17 3:25 ` Wanlong Gao
2013-01-17 19:11 ` Tejun Heo
2013-01-22 5:37 ` Joonsoo Kim
2013-01-23 1:07 ` Tejun Heo
2013-01-24 13:36 ` Lai Jiangshan
2013-01-24 18:51 ` Tejun Heo
2013-01-24 19:03 ` Tejun Heo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1358386969-945-6-git-send-email-tj@kernel.org \
--to=tj@kernel.org \
--cc=laijs@cn.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).