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Message-ID: <20070402054107.GF12962@in.ibm.com>
Date: Mon, 2 Apr 2007 11:11:07 +0530
From: Gautham R Shenoy <ego@...ibm.com>
To: akpm@...ux-foundation.org, paulmck@...ibm.com,
torvalds@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, vatsa@...ibm.com,
Oleg Nesterov <oleg@...sign.ru>,
"Rafael J. Wysocki" <rjw@...k.pl>, mingo@...e.hu,
dipankar@...ibm.com, dino@...ibm.com,
masami.hiramatsu.pt@...achi.com
Subject: [PATCH 6/8] Make non-singlethreaded workqueues freezeable by default
This patch
o Makes all non-singlethreaded workqueues freezeable by default.
o Introduces a new API for creating freeze_exempted workqueues.
o Uses the combination of cancel_delayed_work and cancel_work_sync
in Slab during DOWN_PREPARE instead of cancel_rearming_delayed work,
which tries to flush_workqueue in vain, in a frozen context.
Note:
o The singlethreaded workqueues will not be frozen.
Signed-off-by: Gautham R Shenoy <ego@...ibm.com>
Cc: Oleg Nesterov <oleg@...sign.ru>
Cc: Johannes Berg <johannes@...solutions.net>
--
include/linux/workqueue.h | 12 +++++-------
kernel/workqueue.c | 35 ++++++++++++++++++++++++++---------
mm/slab.c | 10 +++-------
3 files changed, 34 insertions(+), 23 deletions(-)
Index: linux-2.6.21-rc5/include/linux/workqueue.h
===================================================================
--- linux-2.6.21-rc5.orig/include/linux/workqueue.h
+++ linux-2.6.21-rc5/include/linux/workqueue.h
@@ -9,7 +9,6 @@
#include <linux/linkage.h>
#include <linux/bitops.h>
#include <asm/atomic.h>
-
struct workqueue_struct;
struct work_struct;
@@ -112,12 +111,11 @@ struct execute_work {
clear_bit(WORK_STRUCT_PENDING, work_data_bits(work))
-extern struct workqueue_struct *__create_workqueue(const char *name,
- int singlethread,
- int freezeable);
-#define create_workqueue(name) __create_workqueue((name), 0, 0)
-#define create_freezeable_workqueue(name) __create_workqueue((name), 0, 1)
-#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0)
+extern struct workqueue_struct *create_workqueue(const char *name);
+
+extern struct workqueue_struct *create_freeze_exempted_workqueue(const char *name, int freeze_exempt_events);
+
+extern struct workqueue_struct *create_singlethread_workqueue(const char *name);
extern void destroy_workqueue(struct workqueue_struct *wq);
Index: linux-2.6.21-rc5/kernel/workqueue.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/workqueue.c
+++ linux-2.6.21-rc5/kernel/workqueue.c
@@ -64,7 +64,7 @@ struct workqueue_struct {
struct list_head list;
const char *name;
int singlethread;
- int freezeable; /* Freeze threads during suspend */
+ int freeze_exempt_events; /* Events not to freeze! */
};
/* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
@@ -294,8 +294,7 @@ static int worker_thread(void *__cwq)
DEFINE_WAIT(wait);
struct k_sigaction sa;
- if (!cwq->wq->freezeable)
- freezer_exempt(FE_ALL);
+ freezer_exempt(cwq->wq->freeze_exempt_events);
/*
* We inherited MPOL_INTERLEAVE from the booting kernel.
@@ -310,8 +309,7 @@ static int worker_thread(void *__cwq)
do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);
for (;;) {
- if (cwq->wq->freezeable)
- try_to_freeze();
+ try_to_freeze();
prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);
if (cwq->status == CWQ_RUNNING && list_empty(&cwq->worklist))
@@ -656,8 +654,9 @@ static int create_workqueue_thread(struc
return 0;
}
-struct workqueue_struct *__create_workqueue(const char *name,
- int singlethread, int freezeable)
+static struct workqueue_struct *__create_workqueue(const char *name,
+ int singlethread,
+ int freeze_exempt_events)
{
struct workqueue_struct *wq;
struct cpu_workqueue_struct *cwq;
@@ -675,7 +674,7 @@ struct workqueue_struct *__create_workqu
wq->name = name;
wq->singlethread = singlethread;
- wq->freezeable = freezeable;
+ wq->freeze_exempt_events = freeze_exempt_events;
INIT_LIST_HEAD(&wq->list);
if (singlethread) {
@@ -700,7 +699,25 @@ struct workqueue_struct *__create_workqu
}
return wq;
}
-EXPORT_SYMBOL_GPL(__create_workqueue);
+
+struct workqueue_struct *create_workqueue(const char *name)
+{
+ return __create_workqueue(name, 0, FE_NONE);
+}
+EXPORT_SYMBOL_GPL(create_workqueue);
+
+struct workqueue_struct *create_freeze_exempted_workqueue(const char *name,
+ int freeze_exempt_events)
+{
+ return __create_workqueue(name, 0, freeze_exempt_events);
+}
+EXPORT_SYMBOL_GPL(create_freeze_exempted_workqueue);
+
+struct workqueue_struct *create_singlethread_workqueue(const char *name)
+{
+ return __create_workqueue(name, 1, FE_ALL);
+}
+EXPORT_SYMBOL_GPL(create_singlethread_workqueue);
static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
{
Index: linux-2.6.21-rc5/mm/slab.c
===================================================================
--- linux-2.6.21-rc5.orig/mm/slab.c
+++ linux-2.6.21-rc5/mm/slab.c
@@ -1277,13 +1277,9 @@ static int __cpuinit cpuup_callback(stru
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DOWN_PREPARE:
- /*
- * Shutdown cache reaper. Note that the cache_chain_mutex is
- * held so that if cache_reap() is invoked it cannot do
- * anything expensive but will only modify reap_work
- * and reschedule the timer.
- */
- cancel_rearming_delayed_work(&per_cpu(reap_work, cpu));
+ /* we are in a frozen context. So this should be safe.*/
+ cancel_delayed_work(&per_cpu(reap_work, cpu));
+ cancel_work_sync(&per_cpu(reap_work, cpu).work);
/* Now the cache_reaper is guaranteed to be not running. */
per_cpu(reap_work, cpu).work.func = NULL;
break;
--
Gautham R Shenoy
Linux Technology Center
IBM India.
"Freedom comes with a price tag of responsibility, which is still a bargain,
because Freedom is priceless!"
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