[PATCH] IB/mthca: clean up mthca_dereg_mr()

It's cleaner to kfree mthca_mr, and not rely on the fact that ib_mr is the
first field in mthca_mr.
Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <roland@topspin.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/infiniband/hw/mthca/mthca_provider.c

@@ -568,8 +568,9 @@ static struct ib_mr *mthca_reg_phys_mr(struct ib_pd       *pd,
 
 static int mthca_dereg_mr(struct ib_mr *mr)
 {
-	mthca_free_mr(to_mdev(mr->device), to_mmr(mr));
-	kfree(mr);
+	struct mthca_mr *mmr = to_mmr(mr);
+	mthca_free_mr(to_mdev(mr->device), mmr);
+	kfree(mmr);
 	return 0;
 }