s390/pci: resize iomap

BugLink: http://bugs.launchpad.net/bugs/1558624

On s390 we need to maintain a mapping between iomem addresses
and arch specific function identifiers. Currently the mapping
table is created as such that we could span the whole iomem
address space. Since we can only map each bar space from each
possible function we have an upper bound for the number of
mapping entries.

This reduces the size of the iomap from 256K to less than 4K
(using the defconfig).
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
(cherry picked from commit c506fff3)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

arch/s390/pci/pci.c

@@ -68,9 +68,12 @@ static struct airq_struct zpci_airq = {
 	.isc = PCI_ISC,
 };
 
-/* I/O Map */
+#define ZPCI_IOMAP_ENTRIES						\
+	min(((unsigned long) CONFIG_PCI_NR_FUNCTIONS * PCI_BAR_COUNT),	\
+	    ZPCI_IOMAP_MAX_ENTRIES)
+
 static DEFINE_SPINLOCK(zpci_iomap_lock);
-static DECLARE_BITMAP(zpci_iomap, ZPCI_IOMAP_MAX_ENTRIES);
+static unsigned long *zpci_iomap_bitmap;
 struct zpci_iomap_entry *zpci_iomap_start;
 EXPORT_SYMBOL_GPL(zpci_iomap_start);
 
@@ -544,12 +547,12 @@ static int zpci_alloc_iomap(struct zpci_dev *zdev)
 	unsigned long entry;
 
 	spin_lock(&zpci_iomap_lock);
-	entry = find_first_zero_bit(zpci_iomap, ZPCI_IOMAP_MAX_ENTRIES);
-	if (entry == ZPCI_IOMAP_MAX_ENTRIES) {
+	entry = find_first_zero_bit(zpci_iomap_bitmap, ZPCI_IOMAP_ENTRIES);
+	if (entry == ZPCI_IOMAP_ENTRIES) {
 		spin_unlock(&zpci_iomap_lock);
 		return -ENOSPC;
 	}
-	set_bit(entry, zpci_iomap);
+	set_bit(entry, zpci_iomap_bitmap);
 	spin_unlock(&zpci_iomap_lock);
 	return entry;
 }
@@ -558,7 +561,7 @@ static void zpci_free_iomap(struct zpci_dev *zdev, int entry)
 {
 	spin_lock(&zpci_iomap_lock);
 	memset(&zpci_iomap_start[entry], 0, sizeof(struct zpci_iomap_entry));
-	clear_bit(entry, zpci_iomap);
+	clear_bit(entry, zpci_iomap_bitmap);
 	spin_unlock(&zpci_iomap_lock);
 }
 
@@ -869,23 +872,30 @@ static int zpci_mem_init(void)
 	zdev_fmb_cache = kmem_cache_create("PCI_FMB_cache", sizeof(struct zpci_fmb),
 				16, 0, NULL);
 	if (!zdev_fmb_cache)
-		goto error_zdev;
+		goto error_fmb;
 
-	/* TODO: use realloc */
-	zpci_iomap_start = kzalloc(ZPCI_IOMAP_MAX_ENTRIES * sizeof(*zpci_iomap_start),
-				   GFP_KERNEL);
+	zpci_iomap_start = kcalloc(ZPCI_IOMAP_ENTRIES,
+				   sizeof(*zpci_iomap_start), GFP_KERNEL);
 	if (!zpci_iomap_start)
 		goto error_iomap;
-	return 0;
 
+	zpci_iomap_bitmap = kcalloc(BITS_TO_LONGS(ZPCI_IOMAP_ENTRIES),
+				    sizeof(*zpci_iomap_bitmap), GFP_KERNEL);
+	if (!zpci_iomap_bitmap)
+		goto error_iomap_bitmap;
+
+	return 0;
+error_iomap_bitmap:
+	kfree(zpci_iomap_start);
 error_iomap:
 	kmem_cache_destroy(zdev_fmb_cache);
-error_zdev:
+error_fmb:
 	return -ENOMEM;
 }
 
 static void zpci_mem_exit(void)
 {
+	kfree(zpci_iomap_bitmap);
 	kfree(zpci_iomap_start);
 	kmem_cache_destroy(zdev_fmb_cache);
 }