IB/core: Use kmemdup() instead of kmalloc()+memcpy()

Use kmemdup when some other buffer is immediately copied into the
allocated region.

A simplified version of the semantic patch that makes this change is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
expression from,to,size,flag;
statement S;
@@

-  to = \(kmalloc\|kzalloc\)(size,flag);
+  to = kmemdup(from,size,flag);
   if (to==NULL || ...) S
-  memcpy(to, from, size);
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/core/mad.c

@@ -291,13 +291,11 @@ struct ib_mad_agent *ib_register_mad_agent(struct ib_device *device,
 	}
 
 	if (mad_reg_req) {
-		reg_req = kmalloc(sizeof *reg_req, GFP_KERNEL);
+		reg_req = kmemdup(mad_reg_req, sizeof *reg_req, GFP_KERNEL);
 		if (!reg_req) {
 			ret = ERR_PTR(-ENOMEM);
 			goto error3;
 		}
-		/* Make a copy of the MAD registration request */
-		memcpy(reg_req, mad_reg_req, sizeof *reg_req);
 	}
 
 	/* Now, fill in the various structures */