s390/cio: make sch->lock spinlock pointer a member

The lock member of struct subchannel used to be a spinlock, but became
a pointer to a spinlock with commit 2ec2298 ("[S390] subchannel
lock conversion."). This might have been justified back then, but with
the current state of affairs, there is no reason to manage a separate
spinlock object.

Let's simplify things and pull the spinlock back into struct subchannel.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Link: https://lore.kernel.org/r/20231101115751.2308307-1-pasic@linux.ibm.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

Author: halil-pasic

drivers/s390/cio/chsc.c

@@ -219,16 +219,16 @@ EXPORT_SYMBOL_GPL(chsc_sadc);
 
 static int s390_subchannel_remove_chpid(struct subchannel *sch, void *data)
 {
-	spin_lock_irq(sch->lock);
+	spin_lock_irq(&sch->lock);
 	if (sch->driver && sch->driver->chp_event)
 		if (sch->driver->chp_event(sch, data, CHP_OFFLINE) != 0)
 			goto out_unreg;
-	spin_unlock_irq(sch->lock);
+	spin_unlock_irq(&sch->lock);
 	return 0;
 
 out_unreg:
 	sch->lpm = 0;
-	spin_unlock_irq(sch->lock);
+	spin_unlock_irq(&sch->lock);
 	css_schedule_eval(sch->schid);
 	return 0;
 }
@@ -258,10 +258,10 @@ void chsc_chp_offline(struct chp_id chpid)
 
 static int __s390_process_res_acc(struct subchannel *sch, void *data)
 {
-	spin_lock_irq(sch->lock);
+	spin_lock_irq(&sch->lock);
 	if (sch->driver && sch->driver->chp_event)
 		sch->driver->chp_event(sch, data, CHP_ONLINE);
-	spin_unlock_irq(sch->lock);
+	spin_unlock_irq(&sch->lock);
 
 	return 0;
 }
@@ -292,10 +292,10 @@ static void s390_process_res_acc(struct chp_link *link)
 
 static int process_fces_event(struct subchannel *sch, void *data)
 {
-	spin_lock_irq(sch->lock);
+	spin_lock_irq(&sch->lock);
 	if (sch->driver && sch->driver->chp_event)
 		sch->driver->chp_event(sch, data, CHP_FCES_EVENT);
-	spin_unlock_irq(sch->lock);
+	spin_unlock_irq(&sch->lock);
 	return 0;
 }
 
@@ -769,11 +769,11 @@ static void __s390_subchannel_vary_chpid(struct subchannel *sch,
 
 	memset(&link, 0, sizeof(struct chp_link));
 	link.chpid = chpid;
-	spin_lock_irqsave(sch->lock, flags);
+	spin_lock_irqsave(&sch->lock, flags);
 	if (sch->driver && sch->driver->chp_event)
 		sch->driver->chp_event(sch, &link,
 				       on ? CHP_VARY_ON : CHP_VARY_OFF);
-	spin_unlock_irqrestore(sch->lock, flags);
+	spin_unlock_irqrestore(&sch->lock, flags);
 }
 
 static int s390_subchannel_vary_chpid_off(struct subchannel *sch, void *data)

drivers/s390/cio/chsc_sch.c

@@ -211,10 +211,10 @@ static int chsc_async(struct chsc_async_area *chsc_area,
 
 	chsc_area->header.key = PAGE_DEFAULT_KEY >> 4;
 	while ((sch = chsc_get_next_subchannel(sch))) {
-		spin_lock(sch->lock);
+		spin_lock(&sch->lock);
 		private = dev_get_drvdata(&sch->dev);
 		if (private->request) {
-			spin_unlock(sch->lock);
+			spin_unlock(&sch->lock);
 			ret = -EBUSY;
 			continue;
 		}
@@ -239,7 +239,7 @@ static int chsc_async(struct chsc_async_area *chsc_area,
 		default:
 			ret = -ENODEV;
 		}
-		spin_unlock(sch->lock);
+		spin_unlock(&sch->lock);
 		CHSC_MSG(2, "chsc on 0.%x.%04x returned cc=%d\n",
 			 sch->schid.ssid, sch->schid.sch_no, cc);
 		if (ret == -EINPROGRESS)

drivers/s390/cio/cio.c

@@ -546,7 +546,7 @@ static irqreturn_t do_cio_interrupt(int irq, void *dummy)
 		return IRQ_HANDLED;
 	}
 	sch = phys_to_virt(tpi_info->intparm);
-	spin_lock(sch->lock);
+	spin_lock(&sch->lock);
 	/* Store interrupt response block to lowcore. */
 	if (tsch(tpi_info->schid, irb) == 0) {
 		/* Keep subchannel information word up to date. */
@@ -558,7 +558,7 @@ static irqreturn_t do_cio_interrupt(int irq, void *dummy)
 			inc_irq_stat(IRQIO_CIO);
 	} else
 		inc_irq_stat(IRQIO_CIO);
-	spin_unlock(sch->lock);
+	spin_unlock(&sch->lock);
 
 	return IRQ_HANDLED;
 }
@@ -663,7 +663,7 @@ struct subchannel *cio_probe_console(void)
 	if (IS_ERR(sch))
 		return sch;
 
-	lockdep_set_class(sch->lock, &console_sch_key);
+	lockdep_set_class(&sch->lock, &console_sch_key);
 	isc_register(CONSOLE_ISC);
 	sch->config.isc = CONSOLE_ISC;
 	sch->config.intparm = (u32)virt_to_phys(sch);

drivers/s390/cio/cio.h

@@ -83,7 +83,7 @@ enum sch_todo {
 /* subchannel data structure used by I/O subroutines */
 struct subchannel {
 	struct subchannel_id schid;
-	spinlock_t *lock;	/* subchannel lock */
+	spinlock_t lock;	/* subchannel lock */
 	struct mutex reg_mutex;
 	enum {
 		SUBCHANNEL_TYPE_IO = 0,

drivers/s390/cio/css.c

@@ -148,16 +148,10 @@ int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *),
 
 static void css_sch_todo(struct work_struct *work);
 
-static int css_sch_create_locks(struct subchannel *sch)
+static void css_sch_create_locks(struct subchannel *sch)
 {
-	sch->lock = kmalloc(sizeof(*sch->lock), GFP_KERNEL);
-	if (!sch->lock)
-		return -ENOMEM;
-
-	spin_lock_init(sch->lock);
+	spin_lock_init(&sch->lock);
 	mutex_init(&sch->reg_mutex);
-
-	return 0;
 }
 
 static void css_subchannel_release(struct device *dev)
@@ -167,7 +161,6 @@ static void css_subchannel_release(struct device *dev)
 	sch->config.intparm = 0;
 	cio_commit_config(sch);
 	kfree(sch->driver_override);
-	kfree(sch->lock);
 	kfree(sch);
 }
 
@@ -219,9 +212,7 @@ struct subchannel *css_alloc_subchannel(struct subchannel_id schid,
 	sch->schib = *schib;
 	sch->st = schib->pmcw.st;
 
-	ret = css_sch_create_locks(sch);
-	if (ret)
-		goto err;
+	css_sch_create_locks(sch);
 
 	INIT_WORK(&sch->todo_work, css_sch_todo);
 	sch->dev.release = &css_subchannel_release;
@@ -233,19 +224,17 @@ struct subchannel *css_alloc_subchannel(struct subchannel_id schid,
 	 */
 	ret = dma_set_coherent_mask(&sch->dev, DMA_BIT_MASK(31));
 	if (ret)
-		goto err_lock;
+		goto err;
 	/*
 	 * But we don't have such restrictions imposed on the stuff that
 	 * is handled by the streaming API.
 	 */
 	ret = dma_set_mask(&sch->dev, DMA_BIT_MASK(64));
 	if (ret)
-		goto err_lock;
+		goto err;
 
 	return sch;
 
-err_lock:
-	kfree(sch->lock);
 err:
 	kfree(sch);
 	return ERR_PTR(ret);
@@ -604,22 +593,22 @@ static void css_sch_todo(struct work_struct *work)
 
 	sch = container_of(work, struct subchannel, todo_work);
 	/* Find out todo. */
-	spin_lock_irq(sch->lock);
+	spin_lock_irq(&sch->lock);
 	todo = sch->todo;
 	CIO_MSG_EVENT(4, "sch_todo: sch=0.%x.%04x, todo=%d\n", sch->schid.ssid,
 		      sch->schid.sch_no, todo);
 	sch->todo = SCH_TODO_NOTHING;
-	spin_unlock_irq(sch->lock);
+	spin_unlock_irq(&sch->lock);
 	/* Perform todo. */
 	switch (todo) {
 	case SCH_TODO_NOTHING:
 		break;
 	case SCH_TODO_EVAL:
 		ret = css_evaluate_known_subchannel(sch, 1);
 		if (ret == -EAGAIN) {
-			spin_lock_irq(sch->lock);
+			spin_lock_irq(&sch->lock);
 			css_sched_sch_todo(sch, todo);
-			spin_unlock_irq(sch->lock);
+			spin_unlock_irq(&sch->lock);
 		}
 		break;
 	case SCH_TODO_UNREG:
@@ -1028,12 +1017,7 @@ static int __init setup_css(int nr)
 	css->pseudo_subchannel->dev.parent = &css->device;
 	css->pseudo_subchannel->dev.release = css_subchannel_release;
 	mutex_init(&css->pseudo_subchannel->reg_mutex);
-	ret = css_sch_create_locks(css->pseudo_subchannel);
-	if (ret) {
-		kfree(css->pseudo_subchannel);
-		device_unregister(&css->device);
-		goto out_err;
-	}
+	css_sch_create_locks(css->pseudo_subchannel);
 
 	dev_set_name(&css->pseudo_subchannel->dev, "defunct");
 	ret = device_register(&css->pseudo_subchannel->dev);