[src/trunk]: src/sys/kern For secondary CPUs, the idle LWP is the first to ru...

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

details:   https://anonhg.NetBSD.org/src/rev/3c242763da34
branches:  trunk
changeset: 744157:3c242763da34
user:      ad <ad%NetBSD.org@localhost>
date:      Sat Jan 25 20:29:43 2020 +0000

description:
For secondary CPUs, the idle LWP is the first to run, and it's directly
entered from MD code without a trip through mi_switch().  Make the picture
look good in case the CPU takes an interrupt before it calls idle_loop().

diffstat:

 sys/kern/kern_idle.c |  27 ++++++++++++++++++---------
 1 files changed, 18 insertions(+), 9 deletions(-)

diffs (59 lines):

diff -r 0536c6d5a8fb -r 3c242763da34 sys/kern/kern_idle.c
--- a/sys/kern/kern_idle.c      Sat Jan 25 19:22:05 2020 +0000
+++ b/sys/kern/kern_idle.c      Sat Jan 25 20:29:43 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_idle.c,v 1.30 2020/01/08 17:38:42 ad Exp $        */
+/*     $NetBSD: kern_idle.c,v 1.31 2020/01/25 20:29:43 ad Exp $        */
 
 /*-
  * Copyright (c)2002, 2006, 2007 YAMAMOTO Takashi,
@@ -28,7 +28,7 @@
 
 #include <sys/cdefs.h>
 
-__KERNEL_RCSID(0, "$NetBSD: kern_idle.c,v 1.30 2020/01/08 17:38:42 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_idle.c,v 1.31 2020/01/25 20:29:43 ad Exp $");
 
 #include <sys/param.h>
 #include <sys/cpu.h>
@@ -49,17 +49,15 @@
        struct schedstate_percpu *spc;
        struct lwp *l = curlwp;
 
-       kcpuset_atomic_set(kcpuset_running, cpu_index(ci));
+       lwp_lock(l);
        spc = &ci->ci_schedstate;
-       ci->ci_onproc = l;
-
+       KASSERT(lwp_locked(l, spc->spc_lwplock));
+       kcpuset_atomic_set(kcpuset_running, cpu_index(ci));
        /* Update start time for this thread. */
-       lwp_lock(l);
-       KASSERT(lwp_locked(l, spc->spc_lwplock));
        binuptime(&l->l_stime);
        spc->spc_flags |= SPCF_RUNNING;
-       l->l_stat = LSONPROC;
-       l->l_flag |= LW_RUNNING;
+       KASSERT(l->l_stat == LSONPROC);
+       KASSERT((l->l_flag & LW_RUNNING) != 0);
        lwp_unlock(l);
 
        /*
@@ -114,6 +112,17 @@
                panic("create_idle_lwp: error %d", error);
        lwp_lock(l);
        l->l_flag |= LW_IDLE;
+       if (ci != lwp0.l_cpu) {
+               /*
+                * For secondary CPUs, the idle LWP is the first to run, and
+                * it's directly entered from MD code without a trip through
+                * mi_switch().  Make the picture look good in case the CPU
+                * takes an interrupt before it calls idle_loop().
+                */
+               l->l_stat = LSONPROC;
+               l->l_flag |= LW_RUNNING;
+               ci->ci_onproc = l;
+       }
        lwp_unlock(l);
        ci->ci_data.cpu_idlelwp = l;