[RESEND PATCH 0/5] kthread: remove worker->task self-assignment

[RESEND PATCH 0/5] kthread: remove worker->task self-assignment

[Bradley Morgan]

From: Bradley Morgan <brads@mainlining.org>

Resent as a proper series with cover letter. The first send went out as
five separate threads instead of one.

kthread_worker_fn() has carried a FIXME for a decade: it assigns
worker->task = current because the old kthread_run(kthread_worker_fn)
callers never told the worker what task it was. The new
kthread_create_worker*() API sets worker->task before the worker even
starts, so the self-assignment is dead code.

Four drivers were still on the old API. Convert them, then remove the
FIXME.

No functional change intended.

Bradley Morgan (5):
  media: ivtv: convert to kthread_run_worker
  net: encx24j600: convert to kthread_run_worker
  tty: sc16is7xx: convert to kthread_run_worker
  cpufreq: schedutil: convert to kthread_create_worker
  kthread: remove worker->task self-assignment

 drivers/media/pci/ivtv/ivtv-driver.c    | 11 ++++-------
 drivers/media/pci/ivtv/ivtv-driver.h    |  3 +--
 drivers/net/ethernet/microchip/encx24j600.c | 12 ++++--------
 drivers/tty/serial/sc16is7xx.c        | 17 +++++++----------
 kernel/sched/cpufreq_schedutil.c       | 14 +++++--------
 kernel/kthread.c                      |  7 -------
 6 files changed, 21 insertions(+), 63 deletions(-)

[PATCH 1/5] media: ivtv: convert to kthread_run_worker

[Bradley Morgan]

From: Bradley Morgan <brads@mainlining.org>

Embedding a kthread_worker and running kthread_worker_fn yourself is
the old way. Convert ivtv to kthread_run_worker(), dropping the
separate irq_worker_task pointer.

This is part of removing the worker->task self-assignment in
kthread_worker_fn().

Signed-off-by: Bradley Morgan <brads@mainlining.org>
---
 drivers/media/pci/ivtv/ivtv-driver.c | 14 ++++++--------
 drivers/media/pci/ivtv/ivtv-driver.h |  3 +--
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/media/pci/ivtv/ivtv-driver.c b/drivers/media/pci/ivtv/ivtv-driver.c
index b9ea56ec9593..6f0e0e46deb5 100644
--- a/drivers/media/pci/ivtv/ivtv-driver.c
+++ b/drivers/media/pci/ivtv/ivtv-driver.c
@@ -703,15 +703,13 @@ static int ivtv_init_struct1(struct ivtv *itv)
 	spin_lock_init(&itv->lock);
 	spin_lock_init(&itv->dma_reg_lock);
 
-	kthread_init_worker(&itv->irq_worker);
-	itv->irq_worker_task = kthread_run(kthread_worker_fn, &itv->irq_worker,
-					   "%s", itv->v4l2_dev.name);
-	if (IS_ERR(itv->irq_worker_task)) {
+	itv->irq_worker = kthread_run_worker(0, "%s", itv->v4l2_dev.name);
+	if (IS_ERR(itv->irq_worker)) {
 		IVTV_ERR("Could not create ivtv task\n");
 		return -1;
 	}
 	/* must use the FIFO scheduler as it is realtime sensitive */
-	sched_set_fifo(itv->irq_worker_task);
+	sched_set_fifo(itv->irq_worker->task);
 
 	kthread_init_work(&itv->irq_work, ivtv_irq_work_handler);
 
@@ -1232,7 +1230,7 @@ static int ivtv_probe(struct pci_dev *pdev, const struct pci_device_id *pci_id)
 	v4l2_ctrl_handler_free(&itv->cxhdl.hdl);
 	exit_ivtv_i2c(itv);
 free_worker:
-	kthread_stop(itv->irq_worker_task);
+	kthread_destroy_worker(itv->irq_worker);
 err:
 	if (retval == 0)
 		retval = -ENODEV;
@@ -1372,8 +1370,8 @@ static void ivtv_remove(struct pci_dev *pdev)
 	timer_shutdown_sync(&itv->dma_timer);
 
 	/* Kill irq worker */
-	kthread_flush_worker(&itv->irq_worker);
-	kthread_stop(itv->irq_worker_task);
+	kthread_flush_worker(itv->irq_worker);
+	kthread_destroy_worker(itv->irq_worker);
 
 	ivtv_streams_cleanup(itv);
 	ivtv_udma_free(itv);
diff --git a/drivers/media/pci/ivtv/ivtv-driver.h b/drivers/media/pci/ivtv/ivtv-driver.h
index 000e8beecc7c..091bc44f13bc 100644
--- a/drivers/media/pci/ivtv/ivtv-driver.h
+++ b/drivers/media/pci/ivtv/ivtv-driver.h
@@ -668,8 +668,7 @@ struct ivtv {
 	/* Interrupts & DMA */
 	u32 irqmask;                    /* active interrupts */
 	u32 irq_rr_idx;                 /* round-robin stream index */
-	struct kthread_worker irq_worker;		/* kthread worker for PIO/YUV/VBI actions */
-	struct task_struct *irq_worker_task;		/* task for irq_worker */
+	struct kthread_worker *irq_worker;		/* kthread worker for PIO/YUV/VBI actions */
 	struct kthread_work irq_work;	/* kthread work entry */
 	spinlock_t dma_reg_lock;        /* lock access to DMA engine registers */
 	int cur_dma_stream;		/* index of current stream doing DMA (-1 if none) */
-- 
2.47.3

[PATCH 2/5] net: encx24j600: convert to kthread_run_worker

[Bradley Morgan]

From: Bradley Morgan <brads@mainlining.org>

Embedding a kthread_worker and running kthread_worker_fn yourself is
the old way. Convert encx24j600 to kthread_run_worker(), dropping the
separate kworker_task pointer.

This is part of removing the worker->task self-assignment in
kthread_worker_fn().

Signed-off-by: Bradley Morgan <brads@mainlining.org>
---
 drivers/net/ethernet/microchip/encx24j600.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/microchip/encx24j600.c b/drivers/net/ethernet/microchip/encx24j600.c
index b011bf5c2305..460189064332 100644
--- a/drivers/net/ethernet/microchip/encx24j600.c
+++ b/drivers/net/ethernet/microchip/encx24j600.c
@@ -49,8 +49,7 @@ struct encx24j600_priv {
 	struct mutex              lock; /* device access lock */
 	struct encx24j600_context ctx;
 	struct sk_buff           *tx_skb;
-	struct task_struct       *kworker_task;
-	struct kthread_worker     kworker;
+	struct kthread_worker    *kworker;
 	struct kthread_work       tx_work;
 	struct kthread_work       setrx_work;
 	u16                       next_packet;
@@ -823,7 +822,7 @@ static void encx24j600_set_multicast_list(struct net_device *dev)
 	}
 
 	if (oldfilter != priv->rxfilter)
-		kthread_queue_work(&priv->kworker, &priv->setrx_work);
+		kthread_queue_work(priv->kworker, &priv->setrx_work);
 }
 
 static void encx24j600_hw_tx(struct encx24j600_priv *priv)
@@ -884,7 +883,7 @@ static netdev_tx_t encx24j600_tx(struct sk_buff *skb, struct net_device *dev)
 	/* Remember the skb for deferred processing */
 	priv->tx_skb = skb;
 
-	kthread_queue_work(&priv->kworker, &priv->tx_work);
+	kthread_queue_work(priv->kworker, &priv->tx_work);
 
 	return NETDEV_TX_OK;
 }
@@ -1046,15 +1045,12 @@ static int encx24j600_spi_probe(struct spi_device *spi)
 	/* Initialize the device HW to the consistent state */
 	encx24j600_hw_init(priv);
 
-	kthread_init_worker(&priv->kworker);
 	kthread_init_work(&priv->tx_work, encx24j600_tx_proc);
 	kthread_init_work(&priv->setrx_work, encx24j600_setrx_proc);
 
-	priv->kworker_task = kthread_run(kthread_worker_fn, &priv->kworker,
-					 "encx24j600");
-
-	if (IS_ERR(priv->kworker_task)) {
-		ret = PTR_ERR(priv->kworker_task);
+	priv->kworker = kthread_run_worker(0, "encx24j600");
+	if (IS_ERR(priv->kworker)) {
+		ret = PTR_ERR(priv->kworker);
 		goto out_free;
 	}
 
@@ -1087,7 +1083,7 @@ static int encx24j600_spi_probe(struct spi_device *spi)
 out_unregister:
 	unregister_netdev(priv->ndev);
 out_stop:
-	kthread_stop(priv->kworker_task);
+	kthread_destroy_worker(priv->kworker);
 out_free:
 	free_netdev(ndev);
 
@@ -1100,7 +1096,7 @@ static void encx24j600_spi_remove(struct spi_device *spi)
 	struct encx24j600_priv *priv = dev_get_drvdata(&spi->dev);
 
 	unregister_netdev(priv->ndev);
-	kthread_stop(priv->kworker_task);
+	kthread_destroy_worker(priv->kworker);
 
 	free_netdev(priv->ndev);
 }
-- 
2.47.3

[PATCH 3/5] tty: sc16is7xx: convert to kthread_run_worker

[Bradley Morgan]

From: Bradley Morgan <brads@mainlining.org>

Embedding a kthread_worker and running kthread_worker_fn yourself is
the old way. Convert sc16is7xx to kthread_run_worker(), dropping the
separate kworker_task pointer.

This is part of removing the worker->task self-assignment in
kthread_worker_fn().

Signed-off-by: Bradley Morgan <brads@mainlining.org>
---
 drivers/tty/serial/sc16is7xx.c | 39 ++++++++++++++++------------------
 1 file changed, 18 insertions(+), 21 deletions(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 7107a0fb1e7b..2cfc1f290009 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -306,8 +306,7 @@ struct sc16is7xx_port {
 	unsigned long			gpio_valid_mask;
 #endif
 	u8				mctrl_mask;
-	struct kthread_worker		kworker;
-	struct task_struct		*kworker_task;
+	struct kthread_worker		*kworker;
 	struct kthread_delayed_work	poll_work;
 	bool				polling;
 	struct sc16is7xx_one		p[];
@@ -434,7 +433,7 @@ static void sc16is7xx_ier_clear(struct uart_port *port, u8 bit)
 	one->config.flags |= SC16IS7XX_RECONF_IER;
 	one->config.ier_mask |= bit;
 	one->config.ier_val &= ~bit;
-	kthread_queue_work(&s->kworker, &one->reg_work);
+	kthread_queue_work(s->kworker, &one->reg_work);
 }
 
 static void sc16is7xx_ier_set(struct uart_port *port, u8 bit)
@@ -447,7 +446,7 @@ static void sc16is7xx_ier_set(struct uart_port *port, u8 bit)
 	one->config.flags |= SC16IS7XX_RECONF_IER;
 	one->config.ier_mask |= bit;
 	one->config.ier_val |= bit;
-	kthread_queue_work(&s->kworker, &one->reg_work);
+	kthread_queue_work(s->kworker, &one->reg_work);
 }
 
 static void sc16is7xx_stop_tx(struct uart_port *port)
@@ -813,7 +812,7 @@ static void sc16is7xx_poll_proc(struct kthread_work *ws)
 	sc16is7xx_irq(0, s);
 
 	/* Setup delay based on SC16IS7XX_POLL_PERIOD_MS */
-	kthread_queue_delayed_work(&s->kworker, &s->poll_work,
+	kthread_queue_delayed_work(s->kworker, &s->poll_work,
 				   msecs_to_jiffies(SC16IS7XX_POLL_PERIOD_MS));
 }
 
@@ -900,7 +899,7 @@ static void sc16is7xx_ms_proc(struct kthread_work *ws)
 		scoped_guard(mutex, &one->lock)
 			sc16is7xx_update_mlines(one);
 
-		kthread_queue_delayed_work(&s->kworker, &one->ms_work, HZ);
+		kthread_queue_delayed_work(s->kworker, &one->ms_work, HZ);
 	}
 }
 
@@ -911,7 +910,7 @@ static void sc16is7xx_enable_ms(struct uart_port *port)
 
 	lockdep_assert_held_once(&port->lock);
 
-	kthread_queue_delayed_work(&s->kworker, &one->ms_work, 0);
+	kthread_queue_delayed_work(s->kworker, &one->ms_work, 0);
 }
 
 static void sc16is7xx_start_tx(struct uart_port *port)
@@ -919,7 +918,7 @@ static void sc16is7xx_start_tx(struct uart_port *port)
 	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
 	struct sc16is7xx_one *one = to_sc16is7xx_one(port);
 
-	kthread_queue_work(&s->kworker, &one->tx_work);
+	kthread_queue_work(s->kworker, &one->tx_work);
 }
 
 static void sc16is7xx_throttle(struct uart_port *port)
@@ -968,7 +967,7 @@ static void sc16is7xx_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	struct sc16is7xx_one *one = to_sc16is7xx_one(port);
 
 	one->config.flags |= SC16IS7XX_RECONF_MD;
-	kthread_queue_work(&s->kworker, &one->reg_work);
+	kthread_queue_work(s->kworker, &one->reg_work);
 }
 
 static void sc16is7xx_break_ctl(struct uart_port *port, int break_state)
@@ -1098,7 +1097,7 @@ static int sc16is7xx_config_rs485(struct uart_port *port, struct ktermios *termi
 	}
 
 	one->config.flags |= SC16IS7XX_RECONF_RS485;
-	kthread_queue_work(&s->kworker, &one->reg_work);
+	kthread_queue_work(s->kworker, &one->reg_work);
 
 	return 0;
 }
@@ -1159,7 +1158,7 @@ static int sc16is7xx_startup(struct uart_port *port)
 	uart_port_unlock_irqrestore(port, flags);
 
 	if (s->polling)
-		kthread_queue_delayed_work(&s->kworker, &s->poll_work,
+		kthread_queue_delayed_work(s->kworker, &s->poll_work,
 					   msecs_to_jiffies(SC16IS7XX_POLL_PERIOD_MS));
 
 	return 0;
@@ -1186,7 +1185,7 @@ static void sc16is7xx_shutdown(struct uart_port *port)
 	if (s->polling)
 		kthread_cancel_delayed_work_sync(&s->poll_work);
 
-	kthread_flush_worker(&s->kworker);
+	kthread_flush_worker(s->kworker);
 }
 
 static const char *sc16is7xx_type(struct uart_port *port)
@@ -1595,14 +1594,12 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
 	s->devtype = devtype;
 	dev_set_drvdata(dev, s);
 
-	kthread_init_worker(&s->kworker);
-	s->kworker_task = kthread_run(kthread_worker_fn, &s->kworker,
-				      "sc16is7xx");
-	if (IS_ERR(s->kworker_task)) {
-		ret = PTR_ERR(s->kworker_task);
+	s->kworker = kthread_run_worker(0, "sc16is7xx");
+	if (IS_ERR(s->kworker)) {
+		ret = PTR_ERR(s->kworker);
 		goto out_clk;
 	}
-	sched_set_fifo(s->kworker_task);
+	sched_set_fifo(s->kworker->task);
 
 	ret = sc16is7xx_reset(dev, regmaps[0]);
 	if (ret)
@@ -1676,7 +1673,7 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
 	}
 
 out_kthread:
-	kthread_stop(s->kworker_task);
+	kthread_destroy_worker(s->kworker);
 
 out_clk:
 	clk_disable_unprepare(s->clk);
@@ -1705,8 +1702,8 @@ void sc16is7xx_remove(struct device *dev)
 	if (s->polling)
 		kthread_cancel_delayed_work_sync(&s->poll_work);
 
-	kthread_flush_worker(&s->kworker);
-	kthread_stop(s->kworker_task);
+	kthread_flush_worker(s->kworker);
+	kthread_destroy_worker(s->kworker);
 
 	clk_disable_unprepare(s->clk);
 }
-- 
2.47.3

[PATCH 4/5] cpufreq: schedutil: convert to kthread_create_worker

[Bradley Morgan]

From: Bradley Morgan <brads@mainlining.org>

Embedding a kthread_worker and running kthread_worker_fn yourself is
the old way. Convert cpufreq_schedutil to kthread_create_worker(),
dropping the separate thread pointer.

This is part of removing the worker->task self-assignment in
kthread_worker_fn().

Signed-off-by: Bradley Morgan <brads@mainlining.org>
---
 kernel/sched/cpufreq_schedutil.c | 33 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 19 deletions(-)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 49ccd6f1c185..5023c24d8a21 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -31,8 +31,7 @@ struct sugov_policy {
 	struct			irq_work irq_work;
 	struct			kthread_work work;
 	struct			mutex work_lock;
-	struct			kthread_worker worker;
-	struct task_struct	*thread;
+	struct			kthread_worker *worker;
 	bool			work_in_progress;
 
 	bool			limits_changed;
@@ -586,7 +585,7 @@ static void sugov_irq_work(struct irq_work *irq_work)
 
 	sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
 
-	kthread_queue_work(&sg_policy->worker, &sg_policy->work);
+	kthread_queue_work(sg_policy->worker, &sg_policy->work);
 }
 
 /************************** sysfs interface ************************/
@@ -669,7 +668,6 @@ static void sugov_policy_free(struct sugov_policy *sg_policy)
 
 static int sugov_kthread_create(struct sugov_policy *sg_policy)
 {
-	struct task_struct *thread;
 	struct sched_attr attr = {
 		.size		= sizeof(struct sched_attr),
 		.sched_policy	= SCHED_DEADLINE,
@@ -692,32 +690,29 @@ static int sugov_kthread_create(struct sugov_policy *sg_policy)
 		return 0;
 
 	kthread_init_work(&sg_policy->work, sugov_work);
-	kthread_init_worker(&sg_policy->worker);
-	thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
-				"sugov:%d",
-				cpumask_first(policy->related_cpus));
-	if (IS_ERR(thread)) {
-		pr_err("failed to create sugov thread: %pe\n", thread);
-		return PTR_ERR(thread);
+	sg_policy->worker = kthread_create_worker(0, "sugov:%d",
+						cpumask_first(policy->related_cpus));
+	if (IS_ERR(sg_policy->worker)) {
+		pr_err("failed to create sugov thread: %pe\n", sg_policy->worker);
+		return PTR_ERR(sg_policy->worker);
 	}
 
-	ret = sched_setattr_nocheck(thread, &attr);
+	ret = sched_setattr_nocheck(sg_policy->worker->task, &attr);
 	if (ret) {
-		kthread_stop(thread);
+		kthread_destroy_worker(sg_policy->worker);
 		pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
 		return ret;
 	}
 
-	sg_policy->thread = thread;
 	if (policy->dvfs_possible_from_any_cpu)
-		set_cpus_allowed_ptr(thread, policy->related_cpus);
+		set_cpus_allowed_ptr(sg_policy->worker->task, policy->related_cpus);
 	else
-		kthread_bind_mask(thread, policy->related_cpus);
+		kthread_bind_mask(sg_policy->worker->task, policy->related_cpus);
 
 	init_irq_work(&sg_policy->irq_work, sugov_irq_work);
 	mutex_init(&sg_policy->work_lock);
 
-	wake_up_process(thread);
+	wake_up_process(sg_policy->worker->task);
 
 	return 0;
 }
@@ -728,8 +723,8 @@ static void sugov_kthread_stop(struct sugov_policy *sg_policy)
 	if (sg_policy->policy->fast_switch_enabled)
 		return;
 
-	kthread_flush_worker(&sg_policy->worker);
-	kthread_stop(sg_policy->thread);
+	kthread_flush_worker(sg_policy->worker);
+	kthread_destroy_worker(sg_policy->worker);
 	mutex_destroy(&sg_policy->work_lock);
 }
 
-- 
2.47.3

[PATCH] kthread: remove worker->task self-assignment

[Bradley Morgan]

From: Bradley Morgan <brads@mainlining.org>

All kthread worker users now create their workers with
kthread_create_worker*(), which sets worker->task before the worker
starts. The self-assignment in kthread_worker_fn() is dead code now.

Remove it.

Signed-off-by: Bradley Morgan <brads@mainlining.org>
---
 kernel/kthread.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 63beb59b7a3d..18bc702e8d2d 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -987,13 +987,6 @@ int kthread_worker_fn(void *worker_ptr)
 	struct kthread_worker *worker = worker_ptr;
 	struct kthread_work *work;
 
-	/*
-	 * FIXME: Update the check and remove the assignment when all kthread
-	 * worker users are created using kthread_create_worker*() functions.
-	 */
-	WARN_ON(worker->task && worker->task != current);
-	worker->task = current;
-
 	if (worker->flags & KTW_FREEZABLE)
 		set_freezable();
 
-- 
2.47.3

[PATCH] kthread: remove worker->task self-assignment

[Bradley Morgan]

From: Bradley Morgan <brads@mainlining.org>

All kthread worker users now create their workers with
kthread_create_worker*(), which sets worker->task before the worker
starts. The self-assignment in kthread_worker_fn() is dead code now.

Remove it.

Signed-off-by: Bradley Morgan <brads@mainlining.org>
---
 kernel/kthread.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 63beb59b7a3d..18bc702e8d2d 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -987,13 +987,6 @@ int kthread_worker_fn(void *worker_ptr)
 	struct kthread_worker *worker = worker_ptr;
 	struct kthread_work *work;
 
-	/*
-	 * FIXME: Update the check and remove the assignment when all kthread
-	 * worker users are created using kthread_create_worker*() functions.
-	 */
-	WARN_ON(worker->task && worker->task != current);
-	worker->task = current;
-
 	if (worker->flags & KTW_FREEZABLE)
 		set_freezable();
 
-- 
2.47.3