s390/airq: simplify adapter interrupt code

There are three users of adapter interrupts: AP, QDIO and PCI. Each
registers a single adapter interrupt with independent ISCs. Define
a "struct airq" with the interrupt handler, a pointer and a mask for
the local summary indicator and the ISC for the adapter interrupt
source. Convert the indicator array with its fixed number of adapter
interrupt sources per ISE to an array of hlists. This removes the
limitation to 32 adapter interrupts per ISC and allows for arbitrary
memory locations for the local summary indicator.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 72 insertions, 128 deletions

diff --git a/drivers/s390/cio/airq.c b/drivers/s390/cio/airq.c
index bc10220f6847..91edbd7ee806 100644
--- a/drivers/s390/cio/airq.c
+++ b/drivers/s390/cio/airq.c
@@ -9,142 +9,87 @@
  */
 
 #include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/kernel_stat.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/rculist.h>
 #include <linux/slab.h>
-#include <linux/rcupdate.h>
 
 #include <asm/airq.h>
 #include <asm/isc.h>
 
 #include "cio.h"
 #include "cio_debug.h"
+#include "ioasm.h"
 
-#define NR_AIRQS		32
-#define NR_AIRQS_PER_WORD	sizeof(unsigned long)
-#define NR_AIRQ_WORDS		(NR_AIRQS / NR_AIRQS_PER_WORD)
-
-union indicator_t {
-	unsigned long word[NR_AIRQ_WORDS];
-	unsigned char byte[NR_AIRQS];
-} __attribute__((packed));
-
-struct airq_t {
-	adapter_int_handler_t handler;
-	void *drv_data;
-};
-
-static union indicator_t indicators[MAX_ISC+1];
-static struct airq_t *airqs[MAX_ISC+1][NR_AIRQS];
-
-static int register_airq(struct airq_t *airq, u8 isc)
-{
-	int i;
-
-	for (i = 0; i < NR_AIRQS; i++)
-		if (!cmpxchg(&airqs[isc][i], NULL, airq))
-			return i;
-	return -ENOMEM;
-}
+static DEFINE_SPINLOCK(airq_lists_lock);
+static struct hlist_head airq_lists[MAX_ISC+1];
 
 /**
- * s390_register_adapter_interrupt() - register adapter interrupt handler
- * @handler: adapter handler to be registered
- * @drv_data: driver data passed with each call to the handler
- * @isc: isc for which the handler should be called
+ * register_adapter_interrupt() - register adapter interrupt handler
+ * @airq: pointer to adapter interrupt descriptor
  *
- * Returns:
- *  Pointer to the indicator to be used on success
- *  ERR_PTR() if registration failed
+ * Returns 0 on success, or -EINVAL.
  */
-void *s390_register_adapter_interrupt(adapter_int_handler_t handler,
-				      void *drv_data, u8 isc)
+int register_adapter_interrupt(struct airq_struct *airq)
 {
-	struct airq_t *airq;
-	char dbf_txt[16];
-	int ret;
-
-	if (isc > MAX_ISC)
-		return ERR_PTR(-EINVAL);
-	airq = kmalloc(sizeof(struct airq_t), GFP_KERNEL);
-	if (!airq) {
-		ret = -ENOMEM;
-		goto out;
+	char dbf_txt[32];
+
+	if (!airq->handler || airq->isc > MAX_ISC)
+		return -EINVAL;
+	if (!airq->lsi_ptr) {
+		airq->lsi_ptr = kzalloc(1, GFP_KERNEL);
+		if (!airq->lsi_ptr)
+			return -ENOMEM;
+		airq->flags |= AIRQ_PTR_ALLOCATED;
 	}
-	airq->handler = handler;
-	airq->drv_data = drv_data;
-
-	ret = register_airq(airq, isc);
-out:
-	snprintf(dbf_txt, sizeof(dbf_txt), "rairq:%d", ret);
+	if (!airq->lsi_mask)
+		airq->lsi_mask = 0xff;
+	snprintf(dbf_txt, sizeof(dbf_txt), "rairq:%p", airq);
 	CIO_TRACE_EVENT(4, dbf_txt);
-	if (ret < 0) {
-		kfree(airq);
-		return ERR_PTR(ret);
-	} else
-		return &indicators[isc].byte[ret];
+	isc_register(airq->isc);
+	spin_lock(&airq_lists_lock);
+	hlist_add_head_rcu(&airq->list, &airq_lists[airq->isc]);
+	spin_unlock(&airq_lists_lock);
+	return 0;
 }
-EXPORT_SYMBOL(s390_register_adapter_interrupt);
+EXPORT_SYMBOL(register_adapter_interrupt);
 
 /**
- * s390_unregister_adapter_interrupt - unregister adapter interrupt handler
- * @ind: indicator for which the handler is to be unregistered
- * @isc: interruption subclass
+ * unregister_adapter_interrupt - unregister adapter interrupt handler
+ * @airq: pointer to adapter interrupt descriptor
  */
-void s390_unregister_adapter_interrupt(void *ind, u8 isc)
+void unregister_adapter_interrupt(struct airq_struct *airq)
 {
-	struct airq_t *airq;
-	char dbf_txt[16];
-	int i;
+	char dbf_txt[32];
 
-	i = (int) ((addr_t) ind) - ((addr_t) &indicators[isc].byte[0]);
-	snprintf(dbf_txt, sizeof(dbf_txt), "urairq:%d", i);
+	if (hlist_unhashed(&airq->list))
+		return;
+	snprintf(dbf_txt, sizeof(dbf_txt), "urairq:%p", airq);
 	CIO_TRACE_EVENT(4, dbf_txt);
-	indicators[isc].byte[i] = 0;
-	airq = xchg(&airqs[isc][i], NULL);
-	/*
-	 * Allow interrupts to complete. This will ensure that the airq handle
-	 * is no longer referenced by any interrupt handler.
-	 */
-	synchronize_sched();
-	kfree(airq);
+	spin_lock(&airq_lists_lock);
+	hlist_del_rcu(&airq->list);
+	spin_unlock(&airq_lists_lock);
+	synchronize_rcu();
+	isc_unregister(airq->isc);
+	if (airq->flags & AIRQ_PTR_ALLOCATED) {
+		kfree(airq->lsi_ptr);
+		airq->lsi_ptr = NULL;
+		airq->flags &= ~AIRQ_PTR_ALLOCATED;
+	}
 }
-EXPORT_SYMBOL(s390_unregister_adapter_interrupt);
-
-#define INDICATOR_MASK	(0xffUL << ((NR_AIRQS_PER_WORD - 1) * 8))
+EXPORT_SYMBOL(unregister_adapter_interrupt);
 
 void do_adapter_IO(u8 isc)
 {
-	int w;
-	int i;
-	unsigned long word;
-	struct airq_t *airq;
-
-	/*
-	 * Access indicator array in word-sized chunks to minimize storage
-	 * fetch operations.
-	 */
-	for (w = 0; w < NR_AIRQ_WORDS; w++) {
-		word = indicators[isc].word[w];
-		i = w * NR_AIRQS_PER_WORD;
-		/*
-		 * Check bytes within word for active indicators.
-		 */
-		while (word) {
-			if (word & INDICATOR_MASK) {
-				airq = airqs[isc][i];
-				/* Make sure gcc reads from airqs only once. */
-				barrier();
-				if (likely(airq))
-					airq->handler(&indicators[isc].byte[i],
-						      airq->drv_data);
-				else
-					/*
-					 * Reset ill-behaved indicator.
-					 */
-					indicators[isc].byte[i] = 0;
-			}
-			word <<= 8;
-			i++;
-		}
-	}
+	struct airq_struct *airq;
+	struct hlist_head *head;
+
+	head = &airq_lists[isc];
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(airq, head, list)
+		if ((*airq->lsi_ptr & airq->lsi_mask) != 0)
+			airq->handler(airq);
+	rcu_read_unlock();
 }
diff --git a/drivers/s390/cio/qdio_thinint.c b/drivers/s390/cio/qdio_thinint.c
index 417b2557d83e..5d06253c2a7a 100644
--- a/drivers/s390/cio/qdio_thinint.c
+++ b/drivers/s390/cio/qdio_thinint.c
@@ -36,8 +36,13 @@ struct indicator_t {
 static LIST_HEAD(tiq_list);
 static DEFINE_MUTEX(tiq_list_lock);
 
-/* adapter local summary indicator */
-static u8 *tiqdio_alsi;
+/* Adapter interrupt definitions */
+static void tiqdio_thinint_handler(struct airq_struct *airq);
+
+static struct airq_struct tiqdio_airq = {
+	.handler = tiqdio_thinint_handler,
+	.isc = QDIO_AIRQ_ISC,
+};
 
 static struct indicator_t *q_indicators;
 
@@ -176,7 +181,7 @@ static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
  * @alsi: pointer to adapter local summary indicator
  * @data: NULL
  */
-static void tiqdio_thinint_handler(void *alsi, void *data)
+static void tiqdio_thinint_handler(struct airq_struct *airq)
 {
 	u32 si_used = clear_shared_ind();
 	struct qdio_q *q;
@@ -216,7 +221,7 @@ static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
 		summary_indicator_addr = 0;
 		subchannel_indicator_addr = 0;
 	} else {
-		summary_indicator_addr = virt_to_phys(tiqdio_alsi);
+		summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
 		subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
 	}
 
@@ -252,14 +257,12 @@ void tiqdio_free_memory(void)
 
 int __init tiqdio_register_thinints(void)
 {
-	isc_register(QDIO_AIRQ_ISC);
-	tiqdio_alsi = s390_register_adapter_interrupt(&tiqdio_thinint_handler,
-						      NULL, QDIO_AIRQ_ISC);
-	if (IS_ERR(tiqdio_alsi)) {
-		DBF_EVENT("RTI:%lx", PTR_ERR(tiqdio_alsi));
-		tiqdio_alsi = NULL;
-		isc_unregister(QDIO_AIRQ_ISC);
-		return -ENOMEM;
+	int rc;
+
+	rc = register_adapter_interrupt(&tiqdio_airq);
+	if (rc) {
+		DBF_EVENT("RTI:%x", rc);
+		return rc;
 	}
 	return 0;
 }
@@ -292,9 +295,5 @@ void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
 void __exit tiqdio_unregister_thinints(void)
 {
 	WARN_ON(!list_empty(&tiq_list));
-
-	if (tiqdio_alsi) {
-		s390_unregister_adapter_interrupt(tiqdio_alsi, QDIO_AIRQ_ISC);
-		isc_unregister(QDIO_AIRQ_ISC);
-	}
+	unregister_adapter_interrupt(&tiqdio_airq);
 }