Augment rt_task() with is_realtime()

Whenever the kernel checks for rt_task() to avoid delaying real-time
tasks, we want it to also not delay LITMUS^RT tasks.  Hence, most
calls to rt_task() should be matched by an equivalent call to
is_realtime().

Notably, this affects the implementations of select() and nanosleep(),
which use timer_slack_ns when setting up timers for non-real-time
tasks.

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/select.c b/fs/select.c
index 8c1c96c27062..f53b3e421c26 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -28,6 +28,8 @@
 #include <linux/hrtimer.h>
 #include <linux/sched/rt.h>
 
+#include <litmus/litmus.h> /* for is_realtime() */
+
 #include <asm/uaccess.h>
 
 
@@ -77,7 +79,7 @@ long select_estimate_accuracy(struct timespec *tv)
          * Realtime tasks get a slack of 0 for obvious reasons.
          */
 
-        if (rt_task(current))
+        if (rt_task(current) || is_realtime(current))
                 return 0;
 
         ktime_get_ts(&now);