[src/trunk]: src/sys/kern softint_execute(): don't hang onto the kernel_lock ...

[ad <ad%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/cc25d791f0db
branches:  trunk
changeset: 848323:cc25d791f0db
user:      ad <ad%NetBSD.org@localhost>
date:      Sat Jan 25 15:12:47 2020 +0000

description:
softint_execute(): don't hang onto the kernel_lock hold longer than
needed.

diffstat:

 sys/kern/kern_softint.c |  28 +++++++++-------------------
 1 files changed, 9 insertions(+), 19 deletions(-)

diffs (74 lines):

diff -r c756495cde0b -r cc25d791f0db sys/kern/kern_softint.c
--- a/sys/kern/kern_softint.c   Sat Jan 25 15:09:54 2020 +0000
+++ b/sys/kern/kern_softint.c   Sat Jan 25 15:12:47 2020 +0000
@@ -1,7 +1,7 @@
-/*     $NetBSD: kern_softint.c,v 1.57 2020/01/08 17:38:42 ad Exp $     */
+/*     $NetBSD: kern_softint.c,v 1.58 2020/01/25 15:12:47 ad Exp $     */
 
 /*-
- * Copyright (c) 2007, 2008, 2019 The NetBSD Foundation, Inc.
+ * Copyright (c) 2007, 2008, 2019, 2020 The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
@@ -170,7 +170,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_softint.c,v 1.57 2020/01/08 17:38:42 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_softint.c,v 1.58 2020/01/25 15:12:47 ad Exp $");
 
 #include <sys/param.h>
 #include <sys/proc.h>
@@ -544,7 +544,6 @@
 softint_execute(softint_t *si, lwp_t *l, int s)
 {
        softhand_t *sh;
-       bool havelock;
 
 #ifdef __HAVE_FAST_SOFTINTS
        KASSERT(si->si_lwp == curlwp);
@@ -555,8 +554,6 @@
        KASSERT(si->si_lwp->l_wchan == NULL);
        KASSERT(si->si_active);
 
-       havelock = false;
-
        /*
         * Note: due to priority inheritance we may have interrupted a
         * higher priority LWP.  Since the soft interrupt must be quick
@@ -577,17 +574,14 @@
                splx(s);
 
                /* Run the handler. */
-               if (sh->sh_flags & SOFTINT_MPSAFE) {
-                       if (havelock) {
-                               KERNEL_UNLOCK_ONE(l);
-                               havelock = false;
-                       }
-               } else if (!havelock) {
+               if (__predict_true((sh->sh_flags & SOFTINT_MPSAFE) != 0)) {
+                       (*sh->sh_func)(sh->sh_arg);
+               } else {
                        KERNEL_LOCK(1, l);
-                       havelock = true;
+                       (*sh->sh_func)(sh->sh_arg);
+                       KERNEL_UNLOCK_ONE(l);
                }
-               (*sh->sh_func)(sh->sh_arg);
-
+               
                /* Diagnostic: check that spin-locks have not leaked. */
                KASSERTMSG(curcpu()->ci_mtx_count == 0,
                    "%s: ci_mtx_count (%d) != 0, sh_func %p\n",
@@ -603,10 +597,6 @@
 
        PSREF_DEBUG_BARRIER();
 
-       if (havelock) {
-               KERNEL_UNLOCK_ONE(l);
-       }
-
        CPU_COUNT(CPU_COUNT_NSOFT, 1);
 
        KASSERT(si->si_cpu == curcpu());