firewire: core: fw_iso_resource_manage: return -EBUSY when out of resources

Returning -EIO for all errors would not allow clients to determine if
the resource allocation process itself failed, or if the resources are
not available.  (The latter information is needed by CMP to synchronize
restoring of overlayed connections after a bus reset.)

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/core-iso.c

@@ -189,7 +189,7 @@ static int manage_bandwidth(struct fw_card *card, int irm_id, int generation,
 	for (try = 0; try < 5; try++) {
 		new = allocate ? old - bandwidth : old + bandwidth;
 		if (new < 0 || new > BANDWIDTH_AVAILABLE_INITIAL)
-			break;
+			return -EBUSY;
 
 		data[0] = cpu_to_be32(old);
 		data[1] = cpu_to_be32(new);
@@ -217,7 +217,7 @@ static int manage_channel(struct fw_card *card, int irm_id, int generation,
 		u32 channels_mask, u64 offset, bool allocate, __be32 data[2])
 {
 	__be32 c, all, old;
-	int i, retry = 5;
+	int i, ret = -EIO, retry = 5;
 
 	old = all = allocate ? cpu_to_be32(~0) : 0;
 
@@ -225,6 +225,8 @@ static int manage_channel(struct fw_card *card, int irm_id, int generation,
 		if (!(channels_mask & 1 << i))
 			continue;
 
+		ret = -EBUSY;
+
 		c = cpu_to_be32(1 << (31 - i));
 		if ((old & c) != (all & c))
 			continue;
@@ -253,11 +255,13 @@ static int manage_channel(struct fw_card *card, int irm_id, int generation,
 			if (retry) {
 				retry--;
 				i--;
+			} else {
+				ret = -EIO;
 			}
 		}
 	}
 
-	return -EIO;
+	return ret;
 }
 
 static void deallocate_channel(struct fw_card *card, int irm_id,