s390/ap: introduce new ap function ap_get_qdev()

Provide a new interface function to be used by the ap drivers:
  struct ap_queue *ap_get_qdev(ap_qid_t qid);
Returns ptr to the struct ap_queue device or NULL if there
was no ap_queue device with this qid found. When something is
found, the reference count of the embedded device is increased.
So the caller has to decrease the reference count after use
with a call to put_device(&aq->ap_dev.device).

With this patch also the ap_card_list is removed from the
ap core code and a new hashtable is introduced which stores
hnodes of all the ap queues known to the ap bus.

The hashtable approach and a first implementation of this
interface comes from a previous patch from
Anthony Krowiak and an idea from Halil Pasic.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Suggested-by: Tony Krowiak <akrowiak@linux.ibm.com>
Suggested-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 54 insertions, 40 deletions

diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index 35064443e748..e71ca4a719a5 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -62,8 +62,10 @@ MODULE_PARM_DESC(aqmask, "AP bus domain mask.");
 
 static struct device *ap_root_device;
 
-DEFINE_SPINLOCK(ap_list_lock);
-LIST_HEAD(ap_card_list);
+/* Hashtable of all queue devices on the AP bus */
+DEFINE_HASHTABLE(ap_queues, 8);
+/* lock used for the ap_queues hashtable */
+DEFINE_SPINLOCK(ap_queues_lock);
 
 /* Default permissions (ioctl, card and domain masking) */
 struct ap_perms ap_perms;
@@ -414,7 +416,7 @@ static void ap_interrupt_handler(struct airq_struct *airq, bool floating)
  */
 static void ap_tasklet_fn(unsigned long dummy)
 {
-	struct ap_card *ac;
+	int bkt;
 	struct ap_queue *aq;
 	enum ap_wait wait = AP_WAIT_NONE;
 
@@ -425,34 +427,30 @@ static void ap_tasklet_fn(unsigned long dummy)
 	if (ap_using_interrupts())
 		xchg(ap_airq.lsi_ptr, 0);
 
-	spin_lock_bh(&ap_list_lock);
-	for_each_ap_card(ac) {
-		for_each_ap_queue(aq, ac) {
-			spin_lock_bh(&aq->lock);
-			wait = min(wait, ap_sm_event_loop(aq, AP_EVENT_POLL));
-			spin_unlock_bh(&aq->lock);
-		}
+	spin_lock_bh(&ap_queues_lock);
+	hash_for_each(ap_queues, bkt, aq, hnode) {
+		spin_lock_bh(&aq->lock);
+		wait = min(wait, ap_sm_event_loop(aq, AP_EVENT_POLL));
+		spin_unlock_bh(&aq->lock);
 	}
-	spin_unlock_bh(&ap_list_lock);
+	spin_unlock_bh(&ap_queues_lock);
 
 	ap_wait(wait);
 }
 
 static int ap_pending_requests(void)
 {
-	struct ap_card *ac;
+	int bkt;
 	struct ap_queue *aq;
 
-	spin_lock_bh(&ap_list_lock);
-	for_each_ap_card(ac) {
-		for_each_ap_queue(aq, ac) {
-			if (aq->queue_count == 0)
-				continue;
-			spin_unlock_bh(&ap_list_lock);
-			return 1;
-		}
+	spin_lock_bh(&ap_queues_lock);
+	hash_for_each(ap_queues, bkt, aq, hnode) {
+		if (aq->queue_count == 0)
+			continue;
+		spin_unlock_bh(&ap_queues_lock);
+		return 1;
 	}
-	spin_unlock_bh(&ap_list_lock);
+	spin_unlock_bh(&ap_queues_lock);
 	return 0;
 }
 
@@ -683,24 +681,20 @@ static int ap_device_probe(struct device *dev)
 	}
 
 	/* Add queue/card to list of active queues/cards */
-	spin_lock_bh(&ap_list_lock);
-	if (is_card_dev(dev))
-		list_add(&to_ap_card(dev)->list, &ap_card_list);
-	else
-		list_add(&to_ap_queue(dev)->list,
-			 &to_ap_queue(dev)->card->queues);
-	spin_unlock_bh(&ap_list_lock);
+	spin_lock_bh(&ap_queues_lock);
+	if (is_queue_dev(dev))
+		hash_add(ap_queues, &to_ap_queue(dev)->hnode,
+			 to_ap_queue(dev)->qid);
+	spin_unlock_bh(&ap_queues_lock);
 
 	ap_dev->drv = ap_drv;
 	rc = ap_drv->probe ? ap_drv->probe(ap_dev) : -ENODEV;
 
 	if (rc) {
-		spin_lock_bh(&ap_list_lock);
-		if (is_card_dev(dev))
-			list_del_init(&to_ap_card(dev)->list);
-		else
-			list_del_init(&to_ap_queue(dev)->list);
-		spin_unlock_bh(&ap_list_lock);
+		spin_lock_bh(&ap_queues_lock);
+		if (is_queue_dev(dev))
+			hash_del(&to_ap_queue(dev)->hnode);
+		spin_unlock_bh(&ap_queues_lock);
 		ap_dev->drv = NULL;
 	}
 
@@ -725,16 +719,33 @@ static int ap_device_remove(struct device *dev)
 		ap_queue_remove(to_ap_queue(dev));
 
 	/* Remove queue/card from list of active queues/cards */
-	spin_lock_bh(&ap_list_lock);
-	if (is_card_dev(dev))
-		list_del_init(&to_ap_card(dev)->list);
-	else
-		list_del_init(&to_ap_queue(dev)->list);
-	spin_unlock_bh(&ap_list_lock);
+	spin_lock_bh(&ap_queues_lock);
+	if (is_queue_dev(dev))
+		hash_del(&to_ap_queue(dev)->hnode);
+	spin_unlock_bh(&ap_queues_lock);
 
 	return 0;
 }
 
+struct ap_queue *ap_get_qdev(ap_qid_t qid)
+{
+	int bkt;
+	struct ap_queue *aq;
+
+	spin_lock_bh(&ap_queues_lock);
+	hash_for_each(ap_queues, bkt, aq, hnode) {
+		if (aq->qid == qid) {
+			get_device(&aq->ap_dev.device);
+			spin_unlock_bh(&ap_queues_lock);
+			return aq;
+		}
+	}
+	spin_unlock_bh(&ap_queues_lock);
+
+	return NULL;
+}
+EXPORT_SYMBOL(ap_get_qdev);
+
 int ap_driver_register(struct ap_driver *ap_drv, struct module *owner,
 		       char *name)
 {
@@ -1506,6 +1517,9 @@ static int __init ap_module_init(void)
 		return -ENODEV;
 	}
 
+	/* init ap_queue hashtable */
+	hash_init(ap_queues);
+
 	/* set up the AP permissions (ioctls, ap and aq masks) */
 	ap_perms_init();