kernel: exit: Panic if core is not preemptable

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

3 files changed, 22 insertions, 0 deletions

diff --git a/sys/arch/amd64/amd64/proc_machdep.c b/sys/arch/amd64/amd64/proc_machdep.c
index 11b1901..82b4e4f 100644
--- a/sys/arch/amd64/amd64/proc_machdep.c
+++ b/sys/arch/amd64/amd64/proc_machdep.c
@@ -281,6 +281,18 @@ sched_preempt_set(bool enable)
     ci->preempt = enable;
 }
 
+bool
+sched_preemptable(void)
+{
+    struct cpu_info *ci = this_cpu();
+
+    if (ci == NULL) {
+        return false;
+    }
+
+    return ci->preempt;
+}
+
 /*
  * Perform a context switch.
  */
diff --git a/sys/include/sys/sched.h b/sys/include/sys/sched.h
index 8deef95..7bba9df 100644
--- a/sys/include/sys/sched.h
+++ b/sys/include/sys/sched.h
@@ -67,6 +67,8 @@ void sched_stat(struct sched_stat *statp);
 void sched_init(void);
 
 void sched_preempt_set(bool enable);
+bool sched_preemptable(void);
+
 void sched_yield(void);
 void sched_suspend(struct proc *td, const struct timeval *tv);
 void sched_detach(struct proc *td);
diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
index 9377eed..af697d7 100644
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -190,6 +190,14 @@ exit1(struct proc *td, int flags)
      * and do not return.
      */
     if (target_pid == curpid) {
+        /*
+         * If the thread is exiting on a core that is not
+         * preemptable, something is not right.
+         */
+        if (__unlikely(!sched_preemptable())) {
+            panic("exit1: cpu %d not preemptable\n", ci->id);
+        }
+
         ci->curtd = NULL;
         if (parent->pid == 0)
             sched_enter();