RDMA: Use rlimit helpers

Make sure compiler won't do weird things with limits by using the
rlimit helpers added in 3e10e716 ("resource: add helpers for fetching
rlimits").  E.g. fetching them twice may return 2 different values
after writable limits are implemented.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ipath/ipath_user_pages.c b/drivers/infiniband/hw/ipath/ipath_user_pages.c
index 82878e3..eb7d59a 100644
--- a/drivers/infiniband/hw/ipath/ipath_user_pages.c
+++ b/drivers/infiniband/hw/ipath/ipath_user_pages.c
@@ -59,8 +59,7 @@
 	size_t got;
 	int ret;
 
-	lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >>
-		PAGE_SHIFT;
+	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 
 	if (num_pages > lock_limit) {
 		ret = -ENOMEM;