From: Julian Wiedmann <jwi@linux.ibm.com>
Date: Tue, 23 Jul 2019 11:55:27 +0200
Subject: s390/qdio: simplify thinint device registration
Git-commit: 94c43bdaa0073c43a0a1b12e65c51070f02a0642
Patch-mainline: v5.5-rc1
References: jsc#SLE-13690

On an interrupt, tiqdio_thinint_handler() walks a list of all objects
that might require attention, and checks their DSCI. This list is
awkwardly built from Input Queues, even though the IRQs are per-device
and the queue is then only used to dereference its qdio_irq parent.

To simplify the logic, change the code so that tiq_list contains
qdio_irq entries.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/cio/qdio.h         |    8 +++-----
 drivers/s390/cio/qdio_main.c    |    5 +++--
 drivers/s390/cio/qdio_setup.c   |    2 --
 drivers/s390/cio/qdio_thinint.c |   24 +++++++-----------------
 4 files changed, 13 insertions(+), 26 deletions(-)

--- a/drivers/s390/cio/qdio.h
+++ b/drivers/s390/cio/qdio.h
@@ -252,9 +252,6 @@ struct qdio_q {
 	/* input or output queue */
 	int is_input_q;
 
-	/* list of thinint input queues */
-	struct list_head entry;
-
 	/* upper-layer program handler */
 	qdio_handler_t (*handler);
 
@@ -272,6 +269,7 @@ struct qdio_irq {
 	struct qib qib;
 	u32 *dsci;		/* address of device state change indicator */
 	struct ccw_device *cdev;
+	struct list_head entry;		/* list of thinint devices */
 	struct dentry *debugfs_dev;
 	struct dentry *debugfs_perf;
 
@@ -373,8 +371,8 @@ extern u64 last_ai_time;
 void qdio_setup_thinint(struct qdio_irq *irq_ptr);
 int qdio_establish_thinint(struct qdio_irq *irq_ptr);
 void qdio_shutdown_thinint(struct qdio_irq *irq_ptr);
-void tiqdio_add_input_queues(struct qdio_irq *irq_ptr);
-void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr);
+void tiqdio_add_device(struct qdio_irq *irq_ptr);
+void tiqdio_remove_device(struct qdio_irq *irq_ptr);
 void tiqdio_inbound_processing(unsigned long q);
 int tiqdio_allocate_memory(void);
 void tiqdio_free_memory(void);
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -1162,7 +1162,7 @@ int qdio_shutdown(struct ccw_device *cde
 	 */
 	qdio_set_state(irq_ptr, QDIO_IRQ_STATE_STOPPED);
 
-	tiqdio_remove_input_queues(irq_ptr);
+	tiqdio_remove_device(irq_ptr);
 	qdio_shutdown_queues(cdev);
 	qdio_shutdown_debug_entries(irq_ptr);
 
@@ -1284,6 +1284,7 @@ int qdio_allocate(struct qdio_initialize
 			     init_data->no_output_qs))
 		goto out_rel;
 
+	INIT_LIST_HEAD(&irq_ptr->entry);
 	init_data->cdev->private->qdio_data = irq_ptr;
 	qdio_set_state(irq_ptr, QDIO_IRQ_STATE_INACTIVE);
 	return 0;
@@ -1428,7 +1429,7 @@ int qdio_activate(struct ccw_device *cde
 	}
 
 	if (is_thinint_irq(irq_ptr))
-		tiqdio_add_input_queues(irq_ptr);
+		tiqdio_add_device(irq_ptr);
 
 	/* wait for subchannel to become active */
 	msleep(5);
--- a/drivers/s390/cio/qdio_setup.c
+++ b/drivers/s390/cio/qdio_setup.c
@@ -150,7 +150,6 @@ static int __qdio_allocate_qs(struct qdi
 			return -ENOMEM;
 		}
 		irq_ptr_qs[i] = q;
-		INIT_LIST_HEAD(&q->entry);
 	}
 	return 0;
 }
@@ -179,7 +178,6 @@ static void setup_queues_misc(struct qdi
 	q->mask = 1 << (31 - i);
 	q->nr = i;
 	q->handler = handler;
-	INIT_LIST_HEAD(&q->entry);
 }
 
 static void setup_storage_lists(struct qdio_q *q, struct qdio_irq *irq_ptr,
--- a/drivers/s390/cio/qdio_thinint.c
+++ b/drivers/s390/cio/qdio_thinint.c
@@ -66,26 +66,20 @@ static void put_indicator(u32 *addr)
 	atomic_dec(&ind->count);
 }
 
-void tiqdio_add_input_queues(struct qdio_irq *irq_ptr)
+void tiqdio_add_device(struct qdio_irq *irq_ptr)
 {
 	mutex_lock(&tiq_list_lock);
-	list_add_rcu(&irq_ptr->input_qs[0]->entry, &tiq_list);
+	list_add_rcu(&irq_ptr->entry, &tiq_list);
 	mutex_unlock(&tiq_list_lock);
 }
 
-void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
+void tiqdio_remove_device(struct qdio_irq *irq_ptr)
 {
-	struct qdio_q *q;
-
-	q = irq_ptr->input_qs[0];
-	if (!q)
-		return;
-
 	mutex_lock(&tiq_list_lock);
-	list_del_rcu(&q->entry);
+	list_del_rcu(&irq_ptr->entry);
 	mutex_unlock(&tiq_list_lock);
 	synchronize_rcu();
-	INIT_LIST_HEAD(&q->entry);
+	INIT_LIST_HEAD(&irq_ptr->entry);
 }
 
 static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
@@ -174,7 +168,7 @@ static inline void tiqdio_call_inq_handl
 static void tiqdio_thinint_handler(struct airq_struct *airq, bool floating)
 {
 	u32 si_used = clear_shared_ind();
-	struct qdio_q *q;
+	struct qdio_irq *irq;
 
 	last_ai_time = S390_lowcore.int_clock;
 	inc_irq_stat(IRQIO_QAI);
@@ -182,12 +176,8 @@ static void tiqdio_thinint_handler(struc
 	/* protect tiq_list entries, only changed in activate or shutdown */
 	rcu_read_lock();
 
-	/* check for work on all inbound thinint queues */
-	list_for_each_entry_rcu(q, &tiq_list, entry) {
-		struct qdio_irq *irq;
-
+	list_for_each_entry_rcu(irq, &tiq_list, entry) {
 		/* only process queues from changed sets */
-		irq = q->irq_ptr;
 		if (unlikely(references_shared_dsci(irq))) {
 			if (!si_used)
 				continue;