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.

2 files changed, 6 insertions, 2 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index c7f0c79b2cb5..60b6329ab222 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -49,6 +49,7 @@
 #include <linux/timer.h>
 
 #include <litmus/debug_trace.h>
+#include <litmus/litmus.h>
 
 #include <asm/uaccess.h>
 
@@ -1701,7 +1702,7 @@ long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
         unsigned long slack;
 
         slack = current->timer_slack_ns;
-        if (rt_task(current))
+        if (rt_task(current) || is_realtime(current))
                 slack = 0;
 
         hrtimer_init_on_stack(&t.timer, clockid, mode);
diff --git a/kernel/mutex.c b/kernel/mutex.c
index ad53a664f113..a60d05e9498f 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -25,6 +25,8 @@
 #include <linux/interrupt.h>
 #include <linux/debug_locks.h>
 
+#include <litmus/litmus.h>
+
 /*
  * In the DEBUG case we are using the "NULL fastpath" for mutexes,
  * which forces all calls into the slowpath:
@@ -325,7 +327,8 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
                  * we're an RT task that will live-lock because we won't let
                  * the owner complete.
                  */
-                if (!owner && (need_resched() || rt_task(task)))
+                if (!owner && (need_resched() ||
+                               rt_task(task) || is_realtime(task)))
                         break;
 
                 /*