[IA64] bte_copy of BTE_MAX_XFER trips BUG_ON.

BTE_MAX_XFER is wrong.  It is one greater than the number of cache
lines the BTE is actually able to transfer.  If you request a transfer
of exactly BTE_MAX_XFER size, you trip a very cryptic BUG_ON() which
should certainly be made more clear.

This patch fixes that constant and also cleans up the BUG_ON()s in
arch/ia64/sn/kernel/bte.c to test one condition per line.
Signed-off-by: Robin Holt <holt@sgi.com>
Signed-off-by: Tony Luck <aegl@agluck-desktop.(none)>

arch/ia64/include/asm/sn/bte.h

@@ -39,7 +39,7 @@
 /* BTE status register only supports 16 bits for length field */
 #define BTE_LEN_BITS (16)
 #define BTE_LEN_MASK ((1 << BTE_LEN_BITS) - 1)
-#define BTE_MAX_XFER ((1 << BTE_LEN_BITS) * L1_CACHE_BYTES)
+#define BTE_MAX_XFER (BTE_LEN_MASK << L1_CACHE_SHIFT)
 
 
 /* Define hardware */

arch/ia64/sn/kernel/bte.c

@@ -97,9 +97,10 @@ bte_result_t bte_copy(u64 src, u64 dest, u64 len, u64 mode, void *notification)
 		return BTE_SUCCESS;
 	}
 
-	BUG_ON((len & L1_CACHE_MASK) ||
-		 (src & L1_CACHE_MASK) || (dest & L1_CACHE_MASK));
-	BUG_ON(!(len < ((BTE_LEN_MASK + 1) << L1_CACHE_SHIFT)));
+	BUG_ON(len & L1_CACHE_MASK);
+	BUG_ON(src & L1_CACHE_MASK);
+	BUG_ON(dest & L1_CACHE_MASK);
+	BUG_ON(len > BTE_MAX_XFER);
 
 	/*
 	 * Start with interface corresponding to cpu number