s390/ism: indicate correct error reason in ism_alloc_dmb()

When the ism driver allocates a new dmb in ism_alloc_dmb() it must
first check for and reserve a slot in the sba bitmap. When
find_next_zero_bit() finds no free slot then the return code is -ENOMEM.
This code conflicts with the error when the alloc() fails later in the
code. As a result of that the caller can not differentiate
between out-of-memory conditions and sba-bitmap-full conditions.
Fix that by using the return code -ENOSPC when the sba slot
reservation failed.
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/s390/net/ism_drv.c

@@ -231,7 +231,7 @@ static int ism_alloc_dmb(struct ism_dev *ism, struct smcd_dmb *dmb)
 		bit = find_next_zero_bit(ism->sba_bitmap, ISM_NR_DMBS,
 					 ISM_DMB_BIT_OFFSET);
 		if (bit == ISM_NR_DMBS)
-			return -ENOMEM;
+			return -ENOSPC;
 
 		dmb->sba_idx = bit;
 	}