s390/pci: msi cleanup hash usage

The hash used for mapping irq numbers to msi descriptors does not
utilize all buckets that were allocated. Fix this by using the same
value (computed by the number of bits used for the hash function) at
relevant places.
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/pci/pci_msi.c

@@ -18,8 +18,9 @@
 
 /* mapping of irq numbers to msi_desc */
 static struct hlist_head *msi_hash;
-static unsigned int msihash_shift = 6;
-#define msi_hashfn(nr)	hash_long(nr, msihash_shift)
+static const unsigned int msi_hash_bits = 8;
+#define MSI_HASH_BUCKETS (1U << msi_hash_bits)
+#define msi_hashfn(nr)	hash_long(nr, msi_hash_bits)
 
 static DEFINE_SPINLOCK(msi_map_lock);
 
@@ -74,6 +75,7 @@ int zpci_setup_msi_irq(struct zpci_dev *zdev, struct msi_desc *msi,
 	map->irq = nr;
 	map->msi = msi;
 	zdev->msi_map[nr & ZPCI_MSI_MASK] = map;
+	INIT_HLIST_NODE(&map->msi_chain);
 
 	pr_debug("%s hashing irq: %u  to bucket nr: %llu\n",
 		__func__, nr, msi_hashfn(nr));
@@ -125,11 +127,11 @@ int __init zpci_msihash_init(void)
 {
 	unsigned int i;
 
-	msi_hash = kmalloc(256 * sizeof(*msi_hash), GFP_KERNEL);
+	msi_hash = kmalloc(MSI_HASH_BUCKETS * sizeof(*msi_hash), GFP_KERNEL);
 	if (!msi_hash)
 		return -ENOMEM;
 
-	for (i = 0; i < (1U << msihash_shift); i++)
+	for (i = 0; i < MSI_HASH_BUCKETS; i++)
 		INIT_HLIST_HEAD(&msi_hash[i]);
 	return 0;
 }