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[PATCH v5 10/20] kthread: Better support freezable kthread workers

Started byPetr Mladek <pmladek@suse.com>
First post2016-02-22 16:00 +0100
Last post2016-02-26 16:50 +0100
Articles 5 — 3 participants

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  [PATCH v5 10/20] kthread: Better support freezable kthread workers Petr Mladek <pmladek@suse.com> - 2016-02-22 16:00 +0100
    Re: [PATCH v5 10/20] kthread: Better support freezable kthread  workers kbuild test robot <lkp@intel.com> - 2016-02-22 18:40 +0100
      Re: [PATCH v5 10/20] kthread: Better support freezable kthread  workers Petr Mladek <pmladek@suse.com> - 2016-02-24 17:30 +0100
    Re: [PATCH v5 10/20] kthread: Better support freezable kthread  workers Peter Zijlstra <peterz@infradead.org> - 2016-02-25 14:10 +0100
      Re: [PATCH v5 10/20] kthread: Better support freezable kthread  workers Petr Mladek <pmladek@suse.com> - 2016-02-26 16:50 +0100

#1339595 — [PATCH v5 10/20] kthread: Better support freezable kthread workers

FromPetr Mladek <pmladek@suse.com>
Date2016-02-22 16:00 +0100
Subject[PATCH v5 10/20] kthread: Better support freezable kthread workers
Message-ID<r507U-7eO-29@gated-at.bofh.it>
This patch allows to make kthread worker freezable via a new @flags
parameter. It will allow to avoid an init work in some kthreads.

It currently does not affect the function of kthread_worker_fn()
but it might help to do some optimization or fixes eventually.

I currently do not know about any other use for the @flags
parameter but I believe that we will want more flags
in the future.

Finally, I hope that it will not cause confusion with @flags member
in struct kthread. Well, I guess that we will want to rework the
basic kthreads implementation once all kthreads are converted into
kthread workers or workqueues. It is possible that we will merge
the two structures.

Signed-off-by: Petr Mladek <pmladek@suse.com>
---
 include/linux/kthread.h | 11 ++++++++---
 kernel/kthread.c        | 18 ++++++++++++------
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 531730f8a8a7..b57786c40c2c 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -65,7 +65,12 @@ struct kthread_work;
 typedef void (*kthread_work_func_t)(struct kthread_work *work);
 void delayed_kthread_work_timer_fn(unsigned long __data);
 
+enum {
+	KTW_FREEZABLE		= 1 << 2,	/* freeze during suspend */
+};
+
 struct kthread_worker {
+	unsigned int		flags;
 	spinlock_t		lock;
 	struct list_head	work_list;
 	struct list_head	delayed_work_list;
@@ -154,12 +159,12 @@ extern void __init_kthread_worker(struct kthread_worker *worker,
 
 int kthread_worker_fn(void *worker_ptr);
 
-__printf(1, 2)
+__printf(2, 3)
 struct kthread_worker *
-create_kthread_worker(const char namefmt[], ...);
+create_kthread_worker(unsigned int flags, const char namefmt[], ...);
 
 struct kthread_worker *
-create_kthread_worker_on_cpu(int cpu, const char namefmt[]);
+create_kthread_worker_on_cpu(int cpu, unsigned int flags, const char namefmt[]);
 
 bool queue_kthread_work(struct kthread_worker *worker,
 			struct kthread_work *work);
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 686bdd5b6936..643b3088b8d7 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -556,11 +556,11 @@ void __init_kthread_worker(struct kthread_worker *worker,
 				const char *name,
 				struct lock_class_key *key)
 {
+	memset(worker, 0, sizeof(struct kthread_worker));
 	spin_lock_init(&worker->lock);
 	lockdep_set_class_and_name(&worker->lock, key, name);
 	INIT_LIST_HEAD(&worker->work_list);
 	INIT_LIST_HEAD(&worker->delayed_work_list);
-	worker->task = NULL;
 }
 EXPORT_SYMBOL_GPL(__init_kthread_worker);
 
@@ -590,6 +590,10 @@ int kthread_worker_fn(void *worker_ptr)
 	 */
 	WARN_ON(worker->task && worker->task != current);
 	worker->task = current;
+
+	if (worker->flags & KTW_FREEZABLE)
+		set_freezable();
+
 repeat:
 	set_current_state(TASK_INTERRUPTIBLE);	/* mb paired w/ kthread_stop */
 
@@ -623,7 +627,8 @@ repeat:
 EXPORT_SYMBOL_GPL(kthread_worker_fn);
 
 static struct kthread_worker *
-__create_kthread_worker(int cpu, const char namefmt[], va_list args)
+__create_kthread_worker(int cpu, unsigned int flags,
+			const char namefmt[], va_list args)
 {
 	struct kthread_worker *worker;
 	struct task_struct *task;
@@ -643,6 +648,7 @@ __create_kthread_worker(int cpu, const char namefmt[], va_list args)
 	if (IS_ERR(task))
 		goto fail_task;
 
+	worker->flags = flags;
 	worker->task = task;
 	wake_up_process(task);
 	return worker;
@@ -661,13 +667,13 @@ fail_task:
  * when the worker was SIGKILLed.
  */
 struct kthread_worker *
-create_kthread_worker(const char namefmt[], ...)
+create_kthread_worker(unsigned int flags, const char namefmt[], ...)
 {
 	struct kthread_worker *worker;
 	va_list args;
 
 	va_start(args, namefmt);
-	worker = __create_kthread_worker(-1, namefmt, args);
+	worker = __create_kthread_worker(-1, flags, namefmt, args);
 	va_end(args);
 
 	return worker;
@@ -690,9 +696,9 @@ EXPORT_SYMBOL(create_kthread_worker);
  * when the worker was SIGKILLed.
  */
 struct kthread_worker *
-create_kthread_worker_on_cpu(int cpu, const char namefmt[])
+create_kthread_worker_on_cpu(int cpu, unsigned int flags, const char namefmt[])
 {
-	return __create_kthread_worker(cpu, namefmt, NULL);
+	return __create_kthread_worker(cpu, flags, namefmt, NULL);
 }
 EXPORT_SYMBOL(create_kthread_worker_on_cpu);
 
-- 
1.8.5.6

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#1339753 — Re: [PATCH v5 10/20] kthread: Better support freezable kthread workers

Fromkbuild test robot <lkp@intel.com>
Date2016-02-22 18:40 +0100
SubjectRe: [PATCH v5 10/20] kthread: Better support freezable kthread workers
Message-ID<r52CL-Rl-31@gated-at.bofh.it>
In reply to#1339595

[Multipart message — attachments visible in raw view] — view raw

Hi Petr,

[auto build test WARNING on soc-thermal/next]
[also build test WARNING on v4.5-rc5 next-20160222]
[if your patch is applied to the wrong git tree, please drop us a note to help improving the system]

url:    https://github.com/0day-ci/linux/commits/Petr-Mladek/kthread-Use-kthread-worker-API-more-widely/20160222-230250
base:   https://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal next
reproduce: make htmldocs

All warnings (new ones prefixed by >>):

   include/linux/init.h:1: warning: no structured comments found
>> kernel/kthread.c:671: warning: No description found for parameter 'flags'
   kernel/kthread.c:700: warning: No description found for parameter 'flags'
   kernel/kthread.c:866: warning: No description found for parameter 'dwork'
   kernel/kthread.c:866: warning: No description found for parameter 'delay'
   kernel/kthread.c:866: warning: Excess function parameter 'work' description in 'queue_delayed_kthread_work'
   kernel/kthread.c:1063: warning: bad line: 
   kernel/sys.c:1: warning: no structured comments found
   drivers/dma-buf/seqno-fence.c:1: warning: no structured comments found
   drivers/dma-buf/reservation.c:1: warning: no structured comments found
   include/linux/reservation.h:1: warning: no structured comments found
   include/linux/spi/spi.h:540: warning: No description found for parameter 'max_transfer_size'

vim +/flags +671 kernel/kthread.c

bf63ca4b Petr Mladek 2016-02-22  655  
bf63ca4b Petr Mladek 2016-02-22  656  fail_task:
bf63ca4b Petr Mladek 2016-02-22  657  	kfree(worker);
bf63ca4b Petr Mladek 2016-02-22  658  	return ERR_CAST(task);
bf63ca4b Petr Mladek 2016-02-22  659  }
bf63ca4b Petr Mladek 2016-02-22  660  
bf63ca4b Petr Mladek 2016-02-22  661  /**
bf63ca4b Petr Mladek 2016-02-22  662   * create_kthread_worker - create a kthread worker
bf63ca4b Petr Mladek 2016-02-22  663   * @namefmt: printf-style name for the kthread worker (task).
bf63ca4b Petr Mladek 2016-02-22  664   *
bf63ca4b Petr Mladek 2016-02-22  665   * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
bf63ca4b Petr Mladek 2016-02-22  666   * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
bf63ca4b Petr Mladek 2016-02-22  667   * when the worker was SIGKILLed.
bf63ca4b Petr Mladek 2016-02-22  668   */
bf63ca4b Petr Mladek 2016-02-22  669  struct kthread_worker *
28590586 Petr Mladek 2016-02-22  670  create_kthread_worker(unsigned int flags, const char namefmt[], ...)
bf63ca4b Petr Mladek 2016-02-22 @671  {
bf63ca4b Petr Mladek 2016-02-22  672  	struct kthread_worker *worker;
bf63ca4b Petr Mladek 2016-02-22  673  	va_list args;
bf63ca4b Petr Mladek 2016-02-22  674  
bf63ca4b Petr Mladek 2016-02-22  675  	va_start(args, namefmt);
28590586 Petr Mladek 2016-02-22  676  	worker = __create_kthread_worker(-1, flags, namefmt, args);
bf63ca4b Petr Mladek 2016-02-22  677  	va_end(args);
bf63ca4b Petr Mladek 2016-02-22  678  
bf63ca4b Petr Mladek 2016-02-22  679  	return worker;

:::::: The code at line 671 was first introduced by commit
:::::: bf63ca4b5dec706d4b88418b06ccdc1a754b25e4 kthread: Add create_kthread_worker*()

:::::: TO: Petr Mladek <pmladek@suse.com>
:::::: CC: 0day robot <fengguang.wu@intel.com>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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#1342179 — Re: [PATCH v5 10/20] kthread: Better support freezable kthread workers

FromPetr Mladek <pmladek@suse.com>
Date2016-02-24 17:30 +0100
SubjectRe: [PATCH v5 10/20] kthread: Better support freezable kthread workers
Message-ID<r5Ku7-76F-21@gated-at.bofh.it>
In reply to#1339753
On Tue 2016-02-23 01:33:12, kbuild test robot wrote:
> Hi Petr,
> 
> [auto build test WARNING on soc-thermal/next]
> [also build test WARNING on v4.5-rc5 next-20160222]
> [if your patch is applied to the wrong git tree, please drop us a note to help improving the system]
> 
> url:    https://github.com/0day-ci/linux/commits/Petr-Mladek/kthread-Use-kthread-worker-API-more-widely/20160222-230250
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal next
> reproduce: make htmldocs
> 
> All warnings (new ones prefixed by >>):
> 
>    include/linux/init.h:1: warning: no structured comments found
> >> kernel/kthread.c:671: warning: No description found for parameter 'flags'
>    kernel/kthread.c:700: warning: No description found for parameter 'flags'

Please find below an updated version of the patch that fixes the above
warnings:


From 66fbe9142d4761a7010a73eeb69ef315053684cb Mon Sep 17 00:00:00 2001
From: Petr Mladek <pmladek@suse.com>
Date: Mon, 22 Jun 2015 15:05:16 +0200
Subject: [PATCH 10/10] kthread: Better support freezable kthread workers

This patch allows to make kthread worker freezable via a new @flags
parameter. It will allow to avoid an init work in some kthreads.

It currently does not affect the function of kthread_worker_fn()
but it might help to do some optimization or fixes eventually.

I currently do not know about any other use for the @flags
parameter but I believe that we will want more flags
in the future.

Finally, I hope that it will not cause confusion with @flags member
in struct kthread. Well, I guess that we will want to rework the
basic kthreads implementation once all kthreads are converted into
kthread workers or workqueues. It is possible that we will merge
the two structures.

Signed-off-by: Petr Mladek <pmladek@suse.com>
---
 include/linux/kthread.h | 11 ++++++++---
 kernel/kthread.c        | 20 ++++++++++++++------
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 531730f8a8a7..b57786c40c2c 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -65,7 +65,12 @@ struct kthread_work;
 typedef void (*kthread_work_func_t)(struct kthread_work *work);
 void delayed_kthread_work_timer_fn(unsigned long __data);
 
+enum {
+	KTW_FREEZABLE		= 1 << 2,	/* freeze during suspend */
+};
+
 struct kthread_worker {
+	unsigned int		flags;
 	spinlock_t		lock;
 	struct list_head	work_list;
 	struct list_head	delayed_work_list;
@@ -154,12 +159,12 @@ extern void __init_kthread_worker(struct kthread_worker *worker,
 
 int kthread_worker_fn(void *worker_ptr);
 
-__printf(1, 2)
+__printf(2, 3)
 struct kthread_worker *
-create_kthread_worker(const char namefmt[], ...);
+create_kthread_worker(unsigned int flags, const char namefmt[], ...);
 
 struct kthread_worker *
-create_kthread_worker_on_cpu(int cpu, const char namefmt[]);
+create_kthread_worker_on_cpu(int cpu, unsigned int flags, const char namefmt[]);
 
 bool queue_kthread_work(struct kthread_worker *worker,
 			struct kthread_work *work);
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 43b46daafb4d..4450474301c7 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -556,11 +556,11 @@ void __init_kthread_worker(struct kthread_worker *worker,
 				const char *name,
 				struct lock_class_key *key)
 {
+	memset(worker, 0, sizeof(struct kthread_worker));
 	spin_lock_init(&worker->lock);
 	lockdep_set_class_and_name(&worker->lock, key, name);
 	INIT_LIST_HEAD(&worker->work_list);
 	INIT_LIST_HEAD(&worker->delayed_work_list);
-	worker->task = NULL;
 }
 EXPORT_SYMBOL_GPL(__init_kthread_worker);
 
@@ -590,6 +590,10 @@ int kthread_worker_fn(void *worker_ptr)
 	 */
 	WARN_ON(worker->task && worker->task != current);
 	worker->task = current;
+
+	if (worker->flags & KTW_FREEZABLE)
+		set_freezable();
+
 repeat:
 	set_current_state(TASK_INTERRUPTIBLE);	/* mb paired w/ kthread_stop */
 
@@ -623,7 +627,8 @@ repeat:
 EXPORT_SYMBOL_GPL(kthread_worker_fn);
 
 static struct kthread_worker *
-__create_kthread_worker(int cpu, const char namefmt[], va_list args)
+__create_kthread_worker(int cpu, unsigned int flags,
+			const char namefmt[], va_list args)
 {
 	struct kthread_worker *worker;
 	struct task_struct *task;
@@ -643,6 +648,7 @@ __create_kthread_worker(int cpu, const char namefmt[], va_list args)
 	if (IS_ERR(task))
 		goto fail_task;
 
+	worker->flags = flags;
 	worker->task = task;
 	wake_up_process(task);
 	return worker;
@@ -654,6 +660,7 @@ fail_task:
 
 /**
  * create_kthread_worker - create a kthread worker
+ * @flags: flags modifying the default behavior of the worker
  * @namefmt: printf-style name for the kthread worker (task).
  *
  * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
@@ -661,13 +668,13 @@ fail_task:
  * when the worker was SIGKILLed.
  */
 struct kthread_worker *
-create_kthread_worker(const char namefmt[], ...)
+create_kthread_worker(unsigned int flags, const char namefmt[], ...)
 {
 	struct kthread_worker *worker;
 	va_list args;
 
 	va_start(args, namefmt);
-	worker = __create_kthread_worker(-1, namefmt, args);
+	worker = __create_kthread_worker(-1, flags, namefmt, args);
 	va_end(args);
 
 	return worker;
@@ -678,6 +685,7 @@ EXPORT_SYMBOL(create_kthread_worker);
  * create_kthread_worker_on_cpu - create a kthread worker and bind it
  *	it to a given CPU and the associated NUMA node.
  * @cpu: CPU number
+ * @flags: flags modifying the default behavior of the worker
  * @namefmt: printf-style name for the kthread worker (task).
  *
  * Use a valid CPU number if you want to bind the kthread worker
@@ -690,11 +698,11 @@ EXPORT_SYMBOL(create_kthread_worker);
  * when the worker was SIGKILLed.
  */
 struct kthread_worker *
-create_kthread_worker_on_cpu(int cpu, const char namefmt[])
+create_kthread_worker_on_cpu(int cpu, unsigned int flags, const char namefmt[])
 {
 	va_list fake_args;
 
-	return __create_kthread_worker(cpu, namefmt, fake_args);
+	return __create_kthread_worker(cpu, flags, namefmt, fake_args);
 }
 EXPORT_SYMBOL(create_kthread_worker_on_cpu);
 
-- 
1.8.5.6

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#1343152 — Re: [PATCH v5 10/20] kthread: Better support freezable kthread workers

FromPeter Zijlstra <peterz@infradead.org>
Date2016-02-25 14:10 +0100
SubjectRe: [PATCH v5 10/20] kthread: Better support freezable kthread workers
Message-ID<r63Q7-4en-21@gated-at.bofh.it>
In reply to#1339595
On Mon, Feb 22, 2016 at 03:57:00PM +0100, Petr Mladek wrote:
> +enum {
> +	KTW_FREEZABLE		= 1 << 2,	/* freeze during suspend */
> +};

Weird value; what was wrong with 1 << 0 ?

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#1344353 — Re: [PATCH v5 10/20] kthread: Better support freezable kthread workers

FromPetr Mladek <pmladek@suse.com>
Date2016-02-26 16:50 +0100
SubjectRe: [PATCH v5 10/20] kthread: Better support freezable kthread workers
Message-ID<r6sOt-5pp-13@gated-at.bofh.it>
In reply to#1343152
On Thu 2016-02-25 14:01:15, Peter Zijlstra wrote:
> On Mon, Feb 22, 2016 at 03:57:00PM +0100, Petr Mladek wrote:
> > +enum {
> > +	KTW_FREEZABLE		= 1 << 2,	/* freeze during suspend */
> > +};
> 
> Weird value; what was wrong with 1 << 0 ?

Heh, the flag was inspired by

	WQ_FREEZABLE		= 1 << 2, /* freeze during suspend */

from include/linux/workqueue.h. But it does not really matter.
I could change it to 1 << 0 if it makes people less curious.

Thanks a lot for review,
Petr

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