[PATCH v3 0/6] kthread: Add the helper function kthread_run_on_cpu()

[PATCH v3 0/6] kthread: Add the helper function kthread_run_on_cpu()

[Cai Huoqing]

the helper function kthread_run_on_cpu() includes
kthread_create_on_cpu/wake_up_process().
In some cases, use kthread_run_on_cpu() directly instead of
kthread_create_on_node/kthread_bind/wake_up_process() or
kthread_create_on_cpu/wake_up_process() or
kthreadd_create/kthread_bind/wake_up_process() to simplify the code.

v1->v2:
	*Remove cpu_to_node from kthread_create_on_cpu params.
	*Updated the macro description comment.
v2->v3:
	*Convert this helper macro to static inline function
	*Fix typo in changelog
  *Update changelog

v1 link:
	https://lore.kernel.org/lkml/20211021120135.3003-2-caihuoqing@baidu.com/
v2 link:
	https://lore.kernel.org/lkml/20211021122758.3092-2-caihuoqing@baidu.com/

Cai Huoqing (6):
  kthread: Add the helper function kthread_run_on_cpu()
  RDMA/siw: Make use of the helper function kthread_run_on_cpu()
  ring-buffer: Make use of the helper function kthread_run_on_cpu()
  rcutorture: Make use of the helper function kthread_run_on_cpu()
  trace/osnoise: Make use of the helper function kthread_run_on_cpu()
  trace/hwlat: Make use of the helper function kthread_run_on_cpu()

 drivers/infiniband/sw/siw/siw_main.c |  7 +++----
 include/linux/kthread.h              | 25 +++++++++++++++++++++++++
 kernel/rcu/rcutorture.c              |  7 ++-----
 kernel/trace/ring_buffer.c           |  7 ++-----
 kernel/trace/trace_hwlat.c           |  6 +-----
 kernel/trace/trace_osnoise.c         |  3 +--
 6 files changed, 34 insertions(+), 21 deletions(-)

-- 
2.25.1

[PATCH v3 1/6] kthread: Add the helper function kthread_run_on_cpu()

[Cai Huoqing]

the helper function kthread_run_on_cpu() includes
kthread_create_on_cpu/wake_up_process().
In some cases, use kthread_run_on_cpu() directly instead of
kthread_create_on_node/kthread_bind/wake_up_process() or
kthread_create_on_cpu/wake_up_process() or
kthreadd_create/kthread_bind/wake_up_process() to simplify the code.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
---
v1->v2:
	*Remove cpu_to_node from kthread_create_on_cpu params.
	*Updated the macro description comment.
v2->v3:
	*Convert this helper macro to static inline function
	*Fix typo in changelog

v1 link:
	https://lore.kernel.org/lkml/20211021120135.3003-2-caihuoqing@baidu.com/
v2 link:
	https://lore.kernel.org/lkml/20211021122758.3092-2-caihuoqing@baidu.com/

 include/linux/kthread.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 346b0f269161..db47aae7c481 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -56,6 +56,31 @@ bool kthread_is_per_cpu(struct task_struct *k);
 	__k;								   \
 })
 
+/**
+ * kthread_run_on_cpu - create and wake a cpu bound thread.
+ * @threadfn: the function to run until signal_pending(current).
+ * @data: data ptr for @threadfn.
+ * @cpu: The cpu on which the thread should be bound,
+ * @namefmt: printf-style name for the thread. Format is restricted
+ *	     to "name.*%u". Code fills in cpu number.
+ *
+ * Description: Convenient wrapper for kthread_create_on_cpu()
+ * followed by wake_up_process().  Returns the kthread or
+ * ERR_PTR(-ENOMEM).
+ */
+static inline struct task_struct *
+kthread_run_on_cpu(int (*threadfn)(void *data), void *data,
+			unsigned int cpu, const char *namefmt)
+{
+	struct task_struct *p;
+
+	p = kthread_create_on_cpu(threadfn, data, cpu, namefmt);
+	if (!IS_ERR(p))
+		wake_up_process(p);
+
+	return p;
+}
+
 void free_kthread_struct(struct task_struct *k);
 void kthread_bind(struct task_struct *k, unsigned int cpu);
 void kthread_bind_mask(struct task_struct *k, const struct cpumask *mask);
-- 
2.25.1

[PATCH v3 2/6] RDMA/siw: Make use of the helper function kthread_run_on_cpu()

[Cai Huoqing]

Replace kthread_create/kthread_bind/wake_up_process()
with kthread_run_on_cpu() to simplify the code.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
---
 drivers/infiniband/sw/siw/siw_main.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw_main.c b/drivers/infiniband/sw/siw/siw_main.c
index 9093e6a80b26..e5c586913d0b 100644
--- a/drivers/infiniband/sw/siw/siw_main.c
+++ b/drivers/infiniband/sw/siw/siw_main.c
@@ -98,15 +98,14 @@ static int siw_create_tx_threads(void)
 			continue;
 
 		siw_tx_thread[cpu] =
-			kthread_create(siw_run_sq, (unsigned long *)(long)cpu,
-				       "siw_tx/%d", cpu);
+			kthread_run_on_cpu(siw_run_sq,
+					   (unsigned long *)(long)cpu,
+					   cpu, "siw_tx/%u");
 		if (IS_ERR(siw_tx_thread[cpu])) {
 			siw_tx_thread[cpu] = NULL;
 			continue;
 		}
-		kthread_bind(siw_tx_thread[cpu], cpu);
 
-		wake_up_process(siw_tx_thread[cpu]);
 		assigned++;
 	}
 	return assigned;
-- 
2.25.1

[PATCH v3 3/6] ring-buffer: Make use of the helper function kthread_run_on_cpu()

[Cai Huoqing]

Replace kthread_create/kthread_bind/wake_up_process()
with kthread_run_on_cpu() to simplify the code.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
---
 kernel/trace/ring_buffer.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index c5a3fbf19617..afb306e21e5b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -5898,16 +5898,13 @@ static __init int test_ringbuffer(void)
 		rb_data[cpu].buffer = buffer;
 		rb_data[cpu].cpu = cpu;
 		rb_data[cpu].cnt = cpu;
-		rb_threads[cpu] = kthread_create(rb_test, &rb_data[cpu],
-						 "rbtester/%d", cpu);
+		rb_threads[cpu] = kthread_run_on_cpu(rb_test, &rb_data[cpu],
+						     cpu, "rbtester/%u");
 		if (WARN_ON(IS_ERR(rb_threads[cpu]))) {
 			pr_cont("FAILED\n");
 			ret = PTR_ERR(rb_threads[cpu]);
 			goto out_free;
 		}
-
-		kthread_bind(rb_threads[cpu], cpu);
- 		wake_up_process(rb_threads[cpu]);
 	}
 
 	/* Now create the rb hammer! */
-- 
2.25.1

[PATCH v3 4/6] rcutorture: Make use of the helper function kthread_run_on_cpu()

[Cai Huoqing]

Replace kthread_create_on_node/kthread_bind/wake_up_process()
with kthread_run_on_cpu() to simplify the code.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
---
 kernel/rcu/rcutorture.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 503e14e62e8f..6c3ba8c0d7ff 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2025,9 +2025,8 @@ static int rcutorture_booster_init(unsigned int cpu)
 	mutex_lock(&boost_mutex);
 	rcu_torture_disable_rt_throttle();
 	VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
-	boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
-						  cpu_to_node(cpu),
-						  "rcu_torture_boost");
+	boost_tasks[cpu] = kthread_run_on_cpu(rcu_torture_boost, NULL,
+					      cpu, "rcu_torture_boost_%u");
 	if (IS_ERR(boost_tasks[cpu])) {
 		retval = PTR_ERR(boost_tasks[cpu]);
 		VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
@@ -2036,8 +2035,6 @@ static int rcutorture_booster_init(unsigned int cpu)
 		mutex_unlock(&boost_mutex);
 		return retval;
 	}
-	kthread_bind(boost_tasks[cpu], cpu);
-	wake_up_process(boost_tasks[cpu]);
 	mutex_unlock(&boost_mutex);
 	return 0;
 }
-- 
2.25.1

[PATCH v3 5/6] trace/osnoise: Make use of the helper function kthread_run_on_cpu()

[Cai Huoqing]

Replace kthread_create_on_cpu/wake_up_process()
with kthread_run_on_cpu() to simplify the code.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
---
 kernel/trace/trace_osnoise.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index ce053619f289..cbd78fd5e491 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -1525,7 +1525,7 @@ static int start_kthread(unsigned int cpu)
 #else
 	snprintf(comm, 24, "osnoise/%d", cpu);
 #endif
-	kthread = kthread_create_on_cpu(main, NULL, cpu, comm);
+	kthread = kthread_run_on_cpu(main, NULL, cpu, comm);
 
 	if (IS_ERR(kthread)) {
 		pr_err(BANNER "could not start sampling thread\n");
@@ -1534,7 +1534,6 @@ static int start_kthread(unsigned int cpu)
 	}
 
 	per_cpu(per_cpu_osnoise_var, cpu).kthread = kthread;
-	wake_up_process(kthread);
 
 	return 0;
 }
-- 
2.25.1

[PATCH v3 6/6] trace/hwlat: Make use of the helper function kthread_run_on_cpu()

[Cai Huoqing]

Replace kthread_create_on_cpu/wake_up_process()
with kthread_run_on_cpu() to simplify the code.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
---
 kernel/trace/trace_hwlat.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index 1b83d75eb103..0e555335f095 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -491,18 +491,14 @@ static void stop_per_cpu_kthreads(void)
 static int start_cpu_kthread(unsigned int cpu)
 {
 	struct task_struct *kthread;
-	char comm[24];
 
-	snprintf(comm, 24, "hwlatd/%d", cpu);
-
-	kthread = kthread_create_on_cpu(kthread_fn, NULL, cpu, comm);
+	kthread = kthread_run_on_cpu(kthread_fn, NULL, cpu, "hwlatd/%u");
 	if (IS_ERR(kthread)) {
 		pr_err(BANNER "could not start sampling thread\n");
 		return -ENOMEM;
 	}
 
 	per_cpu(hwlat_per_cpu_data, cpu).kthread = kthread;
-	wake_up_process(kthread);
 
 	return 0;
 }
-- 
2.25.1

RE: [PATCH v3 1/6] kthread: Add the helper function kthread_run_on_cpu()

[Cai,Huoqing]

Hello,
Just a ping, to see if there are any more comments :-P
> -----Original Message-----
> From: Cai,Huoqing <caihuoqing@baidu.com>
> Sent: 2021年10月22日 10:57
> Subject: [PATCH v3 1/6] kthread: Add the helper function kthread_run_on_cpu()
> 
> the helper function kthread_run_on_cpu() includes
> kthread_create_on_cpu/wake_up_process().
> In some cases, use kthread_run_on_cpu() directly instead of
> kthread_create_on_node/kthread_bind/wake_up_process() or
> kthread_create_on_cpu/wake_up_process() or
> kthreadd_create/kthread_bind/wake_up_process() to simplify the code.
> 
> Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
> ---
> v1->v2:
> 	*Remove cpu_to_node from kthread_create_on_cpu params.
> 	*Updated the macro description comment.
> v2->v3:
> 	*Convert this helper macro to static inline function
> 	*Fix typo in changelog
> 
> v1 link:
> 	https://lore.kernel.org/lkml/20211021120135.3003-2-
> caihuoqing@baidu.com/
> v2 link:
> 	https://lore.kernel.org/lkml/20211021122758.3092-2-
> caihuoqing@baidu.com/
> 
>  include/linux/kthread.h | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/include/linux/kthread.h b/include/linux/kthread.h
> index 346b0f269161..db47aae7c481 100644
> --- a/include/linux/kthread.h
> +++ b/include/linux/kthread.h
> @@ -56,6 +56,31 @@ bool kthread_is_per_cpu(struct task_struct *k);
>  	__k;								   \
>  })
> 
> +/**
> + * kthread_run_on_cpu - create and wake a cpu bound thread.
> + * @threadfn: the function to run until signal_pending(current).
> + * @data: data ptr for @threadfn.
> + * @cpu: The cpu on which the thread should be bound,
> + * @namefmt: printf-style name for the thread. Format is restricted
> + *	     to "name.*%u". Code fills in cpu number.
> + *
> + * Description: Convenient wrapper for kthread_create_on_cpu()
> + * followed by wake_up_process().  Returns the kthread or
> + * ERR_PTR(-ENOMEM).
> + */
> +static inline struct task_struct *
> +kthread_run_on_cpu(int (*threadfn)(void *data), void *data,
> +			unsigned int cpu, const char *namefmt)
> +{
> +	struct task_struct *p;
> +
> +	p = kthread_create_on_cpu(threadfn, data, cpu, namefmt);
> +	if (!IS_ERR(p))
> +		wake_up_process(p);
> +
> +	return p;
> +}
> +
>  void free_kthread_struct(struct task_struct *k);
>  void kthread_bind(struct task_struct *k, unsigned int cpu);
>  void kthread_bind_mask(struct task_struct *k, const struct cpumask *mask);
> --
> 2.25.1

Re: [PATCH v3 1/6] kthread: Add the helper function kthread_run_on_cpu()

[Steven Rostedt]

On Tue, 26 Oct 2021 08:32:30 +0000
"Cai,Huoqing" <caihuoqing@baidu.com> wrote:

> Hello,
> Just a ping, to see if there are any more comments :-P

I have no real issue with this patch set. As it seems to be a generic clean
up, perhaps Andrew might like to take a look at it, and if he's fine with
it, he can take it through his tree?

-- Steve


> > -----Original Message-----
> > From: Cai,Huoqing <caihuoqing@baidu.com>
> > Sent: 2021年10月22日 10:57
> > Subject: [PATCH v3 1/6] kthread: Add the helper function kthread_run_on_cpu()
> > 
> > the helper function kthread_run_on_cpu() includes
> > kthread_create_on_cpu/wake_up_process().
> > In some cases, use kthread_run_on_cpu() directly instead of
> > kthread_create_on_node/kthread_bind/wake_up_process() or
> > kthread_create_on_cpu/wake_up_process() or
> > kthreadd_create/kthread_bind/wake_up_process() to simplify the code.
> > 
> > Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
> > ---
> > v1->v2:
> > 	*Remove cpu_to_node from kthread_create_on_cpu params.
> > 	*Updated the macro description comment.
> > v2->v3:
> > 	*Convert this helper macro to static inline function
> > 	*Fix typo in changelog
> > 
> > v1 link:
> > 	https://lore.kernel.org/lkml/20211021120135.3003-2-
> > caihuoqing@baidu.com/
> > v2 link:
> > 	https://lore.kernel.org/lkml/20211021122758.3092-2-
> > caihuoqing@baidu.com/
> > 
> >  include/linux/kthread.h | 25 +++++++++++++++++++++++++
> >  1 file changed, 25 insertions(+)
> > 
> > diff --git a/include/linux/kthread.h b/include/linux/kthread.h
> > index 346b0f269161..db47aae7c481 100644
> > --- a/include/linux/kthread.h
> > +++ b/include/linux/kthread.h
> > @@ -56,6 +56,31 @@ bool kthread_is_per_cpu(struct task_struct *k);
> >  	__k;								   \
> >  })
> > 
> > +/**
> > + * kthread_run_on_cpu - create and wake a cpu bound thread.
> > + * @threadfn: the function to run until signal_pending(current).
> > + * @data: data ptr for @threadfn.
> > + * @cpu: The cpu on which the thread should be bound,
> > + * @namefmt: printf-style name for the thread. Format is restricted
> > + *	     to "name.*%u". Code fills in cpu number.
> > + *
> > + * Description: Convenient wrapper for kthread_create_on_cpu()
> > + * followed by wake_up_process().  Returns the kthread or
> > + * ERR_PTR(-ENOMEM).
> > + */
> > +static inline struct task_struct *
> > +kthread_run_on_cpu(int (*threadfn)(void *data), void *data,
> > +			unsigned int cpu, const char *namefmt)
> > +{
> > +	struct task_struct *p;
> > +
> > +	p = kthread_create_on_cpu(threadfn, data, cpu, namefmt);
> > +	if (!IS_ERR(p))
> > +		wake_up_process(p);
> > +
> > +	return p;
> > +}
> > +
> >  void free_kthread_struct(struct task_struct *k);
> >  void kthread_bind(struct task_struct *k, unsigned int cpu);
> >  void kthread_bind_mask(struct task_struct *k, const struct cpumask *mask);
> > --
> > 2.25.1  
>