[IA64] use helpers for rlimits

Make sure compiler won't do weird things with limits. E.g. fetching
them twice may return 2 different values after writable limits are
implemented.

I.e. either use rlimit helpers added in
3e10e716
or ACCESS_ONCE if not applicable.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/perfmon.c

@@ -2293,7 +2293,7 @@ pfm_smpl_buffer_alloc(struct task_struct *task, struct file *filp, pfm_context_t
 	 * if ((mm->total_vm << PAGE_SHIFT) + len> task->rlim[RLIMIT_AS].rlim_cur)
 	 * 	return -ENOMEM;
 	 */
-	if (size > task->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
+	if (size > task_rlimit(task, RLIMIT_MEMLOCK))
 		return -ENOMEM;
 
 	/*

arch/ia64/mm/init.c

@@ -91,7 +91,7 @@ dma_mark_clean(void *addr, size_t size)
 inline void
 ia64_set_rbs_bot (void)
 {
-	unsigned long stack_size = current->signal->rlim[RLIMIT_STACK].rlim_max & -16;
+	unsigned long stack_size = rlimit_max(RLIMIT_STACK) & -16;
 
 	if (stack_size > MAX_USER_STACK_SIZE)
 		stack_size = MAX_USER_STACK_SIZE;