Gabriele Monaco [off-list ref] writes:

+/*
+ * Dummy values if not available
+ */
+#ifndef __NR_sched_setscheduler
+#define __NR_sched_setscheduler -1
+#endif
+#ifndef __NR_sched_setattr
+#define __NR_sched_setattr -2
+#endif

You can use __COUNTER__ intead, would make it easier to add to or remove
from this list later on.

+static void handle_syscall(void *data, struct pt_regs *regs, long id)
+{
+	struct task_struct *p;
+	int new_policy = -1;
+
+	new_policy = extract_params(regs, id, &p);
+	if (new_policy < 0 || new_policy == p->policy)
+		return;
+	if (p->policy == SCHED_DEADLINE)
+		da_reset(EXPAND_ID(&p->dl, DL_TASK));
+	else if (new_policy == SCHED_DEADLINE)
+		da_create_conditional(EXPAND_ID(&p->dl, DL_TASK), GFP_NOWAIT);
+}

What if the syscall fails for any reason? Wouldn't the monitor stores
incorrect information?

Nam