systm.h: Remove unused <sys/kpilite.h>

It only contains sched_pin_lite() and sched_unpin_lite(), which have
been unused in-tree for the past 8 years, and were only briefly used
between 6573d7580b ("epoch(9): allow preemptible epochs to compose")
and a760c50c9e ("With epoch not inlined, there is no point in using
_lite KPI. (...)").

Additionally, these functions are redundant with the existing
sched_pin() and sched_unpin() in <sys/sched.h>, which are already
themselves inline functions.  The only difference is that the
sched_*_lite() ones do not require the full definition of 'struct
thread', which may have been useful to circumvent namespace pollution.

That problem, if it materializes again, could be quickly circumvented
without this trickery by the use of non-inline functions, or using
inline functions referencing a variable filled at kernel startup with
the desired offset.  The trickery of using offsets computed at
compile-time appears necessary only in the case of extremely performance
sensitive functions.  Cleaning up namespace pollution should stay the
preferred way forward whenever possible.

Reviewed by:    glebius, imp
MFC after:      3 days
Sponsored by:   The FreeBSD Foundation
Differential Revision:  https://reviews.freebsd.org/D60404

sys/sys/kpilite.h

@@ -1,52 +0,0 @@
-/*-
- * SPDX-License-Identifier: BSD-2-Clause
- *
- * Copyright (c) 2018, Matthew Macy <mmacy@freebsd.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#ifndef _SYS_KPILITE_H_
-#define _SYS_KPILITE_H_
-#if !defined(GENOFFSET) && (!defined(KLD_MODULE) || defined(KLD_TIED)) && defined(_KERNEL)
-#include "offset.inc"
-
-static __inline void
-sched_pin_lite(struct thread_lite *td)
-{
-
-	KASSERT((struct thread *)td == curthread, ("sched_pin called on non curthread"));
-	td->td_pinned++;
-	atomic_interrupt_fence();
-}
-
-static __inline void
-sched_unpin_lite(struct thread_lite *td)
-{
-
-	KASSERT((struct thread *)td == curthread, ("sched_unpin called on non curthread"));
-	KASSERT(td->td_pinned > 0, ("sched_unpin called on non pinned thread"));
-	atomic_interrupt_fence();
-	td->td_pinned--;
-}
-#endif
-#endif

sys/sys/systm.h

@@ -97,7 +97,6 @@ struct ucred;
 #ifdef _KERNEL
 #include <sys/param.h>		/* MAXCPU */
 #include <sys/pcpu.h>		/* curthread */
-#include <sys/kpilite.h>
 #include <sys/limits.h>
 
 extern bool scheduler_stopped;
@@ -177,6 +176,7 @@ int linux_alloc_current_noop(struct thread *, int);
 #define critical_enter() critical_enter_KBI()
 #define critical_exit() critical_exit_KBI()
 #else
+#include "offset.inc"
 static __inline void
 critical_enter(void)
 {