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>

drivers/infiniband/core/umem.c

@@ -136,7 +136,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
 	down_write(&current->mm->mmap_sem);
 
 	locked     = npages + current->mm->locked_vm;
-	lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
+	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 
 	if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
 		ret = -ENOMEM;

drivers/infiniband/hw/ipath/ipath_user_pages.c

@@ -59,8 +59,7 @@ static int __get_user_pages(unsigned long start_page, size_t num_pages,
 	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;