kernel core: 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 commit 3e10e716abf3 ("resource:
add helpers for fetching rlimits") or ACCESS_ONCE if not applicable.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index bf3e38fdbe6..5a6ed1f0990 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1662,8 +1662,9 @@ static void watchdog(struct rq *rq, struct task_struct *p)
         if (!p->signal)
                 return;
 
-        soft = p->signal->rlim[RLIMIT_RTTIME].rlim_cur;
-        hard = p->signal->rlim[RLIMIT_RTTIME].rlim_max;
+        /* max may change after cur was read, this will be fixed next tick */
+        soft = task_rlimit(p, RLIMIT_RTTIME);
+        hard = task_rlimit_max(p, RLIMIT_RTTIME);
 
         if (soft != RLIM_INFINITY) {
                 unsigned long next;