kernel: Allow preemption to be enabled/disabled

Introduce sched_preempt_set() which can be useful to implement priority
inheritance for preventing priority inversion

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/sys/arch/amd64/amd64/proc_machdep.c b/sys/arch/amd64/amd64/proc_machdep.c
index 56348be..11b1901 100644
--- a/sys/arch/amd64/amd64/proc_machdep.c
+++ b/sys/arch/amd64/amd64/proc_machdep.c
@@ -264,6 +264,24 @@ sched_switch_to(struct trapframe *tf, struct proc *td)
 }
 
 /*
+ * Enable or disable preemption on the current
+ * processor
+ *
+ * @enable: Enable preemption if true
+ */
+void
+sched_preempt_set(bool enable)
+{
+    struct cpu_info *ci = this_cpu();
+
+    if (ci == NULL) {
+        return;
+    }
+
+    ci->preempt = enable;
+}
+
+/*
  * Perform a context switch.
  */
 void