ipv4: Use IS_ERR_OR_NULL().

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2aa69c8..5227194 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3243,7 +3243,7 @@
 		struct crypto_hash *hash;
 
 		hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
-		if (!hash || IS_ERR(hash))
+		if (IS_ERR_OR_NULL(hash))
 			goto out_free;
 
 		per_cpu_ptr(pool, cpu)->md5_desc.tfm = hash;