s390/airq: provide cacheline aligned ivs

Provide the ability to create cachesize aligned interrupt vectors.
These will be used for per-CPU interrupt vectors.
Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/airq.h

@@ -35,6 +35,7 @@ struct airq_iv {
 	unsigned int *data;	/* 32 bit value associated with each bit */
 	unsigned long bits;	/* Number of bits in the vector */
 	unsigned long end;	/* Number of highest allocated bit + 1 */
+	unsigned long flags;	/* Allocation flags */
 	spinlock_t lock;	/* Lock to protect alloc & free */
 };
 
@@ -42,6 +43,7 @@ struct airq_iv {
 #define AIRQ_IV_BITLOCK		2	/* Allocate the lock bit mask */
 #define AIRQ_IV_PTR		4	/* Allocate the ptr array */
 #define AIRQ_IV_DATA		8	/* Allocate the data array */
+#define AIRQ_IV_CACHELINE	16	/* Cacheline alignment for the vector */
 
 struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags);
 void airq_iv_release(struct airq_iv *iv);

drivers/s390/cio/airq.c

@@ -27,6 +27,8 @@
 static DEFINE_SPINLOCK(airq_lists_lock);
 static struct hlist_head airq_lists[MAX_ISC+1];
 
+static struct kmem_cache *airq_iv_cache;
+
 /**
  * register_adapter_interrupt() - register adapter interrupt handler
  * @airq: pointer to adapter interrupt descriptor
@@ -129,10 +131,21 @@ struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags)
 	if (!iv)
 		goto out;
 	iv->bits = bits;
+	iv->flags = flags;
 	size = BITS_TO_LONGS(bits) * sizeof(unsigned long);
+
+	if (flags & AIRQ_IV_CACHELINE) {
+		if ((cache_line_size() * BITS_PER_BYTE) < bits)
+			goto out_free;
+
+		iv->vector = kmem_cache_zalloc(airq_iv_cache, GFP_KERNEL);
+		if (!iv->vector)
+			goto out_free;
+	} else {
 		iv->vector = kzalloc(size, GFP_KERNEL);
 		if (!iv->vector)
 			goto out_free;
+	}
 	if (flags & AIRQ_IV_ALLOC) {
 		iv->avail = kmalloc(size, GFP_KERNEL);
 		if (!iv->avail)
@@ -165,6 +178,9 @@ struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags)
 	kfree(iv->ptr);
 	kfree(iv->bitlock);
 	kfree(iv->avail);
+	if (iv->flags & AIRQ_IV_CACHELINE)
+		kmem_cache_free(airq_iv_cache, iv->vector);
+	else
 		kfree(iv->vector);
 	kfree(iv);
 out:
@@ -181,6 +197,9 @@ void airq_iv_release(struct airq_iv *iv)
 	kfree(iv->data);
 	kfree(iv->ptr);
 	kfree(iv->bitlock);
+	if (iv->flags & AIRQ_IV_CACHELINE)
+		kmem_cache_free(airq_iv_cache, iv->vector);
+	else
 		kfree(iv->vector);
 	kfree(iv->avail);
 	kfree(iv);
@@ -275,3 +294,13 @@ unsigned long airq_iv_scan(struct airq_iv *iv, unsigned long start,
 	return bit;
 }
 EXPORT_SYMBOL(airq_iv_scan);
+
+static int __init airq_init(void)
+{
+	airq_iv_cache = kmem_cache_create("airq_iv_cache", cache_line_size(),
+					  cache_line_size(), 0, NULL);
+	if (!airq_iv_cache)
+		return -ENOMEM;
+	return 0;
+}
+subsys_initcall(airq_init);