make critical_{enter, exit} inline

Avoid pulling in all of the <sys/proc.h> dependencies by
automatically generating a stripped down thread_lite exporting
only the fields of interest. The field declarations are type checked
against the original and the offsets of the generated result is
automatically checked.

kib has expressed disagreement and would have preferred to simply
use genassym style offsets (which loses type check enforcement).
jhb has expressed dislike of it due to header pollution and a
duplicate structure. He would have preferred to just have defined
thread in _thread.h. Nonetheless, he admits that this is the only
viable solution at the moment.

The impetus for this came from mjg's D15331:
"Inline critical_enter/exit for amd64"

Reviewed by: jeff
Differential Revision: https://reviews.freebsd.org/D16078

1 files changed, 11 insertions, 16 deletions

diff --git a/sys/kern/kern_switch.c b/sys/kern/kern_switch.c
index ee7d65d8b261..254c4ffd2674 100644
--- a/sys/kern/kern_switch.c
+++ b/sys/kern/kern_switch.c
@@ -199,17 +199,17 @@ choosethread(void)
  * the function call itself, for most cases.
  */
 void
-critical_enter(void)
+critical_enter_KBI(void)
 {
-	struct thread *td;
-
-	td = curthread;
-	td->td_critnest++;
+#ifdef KTR
+	struct thread *td = curthread;
+#endif
+	critical_enter();
 	CTR4(KTR_CRITICAL, "critical_enter by thread %p (%ld, %s) to %d", td,
 	    (long)td->td_proc->p_pid, td->td_name, td->td_critnest);
 }
 
-static void __noinline
+void __noinline
 critical_exit_preempt(void)
 {
 	struct thread *td;
@@ -245,17 +245,12 @@ critical_exit_preempt(void)
 }
 
 void
-critical_exit(void)
+critical_exit_KBI(void)
 {
-	struct thread *td;
-
-	td = curthread;
-	KASSERT(td->td_critnest != 0,
-	    ("critical_exit: td_critnest == 0"));
-	td->td_critnest--;
-	__compiler_membar();
-	if (__predict_false(td->td_owepreempt))
-		critical_exit_preempt();
+#ifdef KTR
+	struct thread *td = curthread;
+#endif
+	critical_exit();
 	CTR4(KTR_CRITICAL, "critical_exit by thread %p (%ld, %s) to %d", td,
 	    (long)td->td_proc->p_pid, td->td_name, td->td_critnest);
 }