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[src/trunk]: src/sys - Move the LW_RUNNING flag back into l_pflag: updating l...
details: https://anonhg.NetBSD.org/src/rev/8c8d23a1cb87
branches: trunk
changeset: 744888:8c8d23a1cb87
user: ad <ad%NetBSD.org@localhost>
date: Sat Feb 15 18:12:14 2020 +0000
description:
- Move the LW_RUNNING flag back into l_pflag: updating l_flag without lock
in softint_dispatch() is risky. May help with the "softint screwup"
panic.
- Correct the memory barriers around zombies switching into oblivion.
diffstat:
sys/arch/vax/vax/pmap.c | 6 ++--
sys/ddb/db_proc.c | 12 +++++-----
sys/kern/init_main.c | 6 ++--
sys/kern/kern_exit.c | 9 ++-----
sys/kern/kern_idle.c | 8 +++---
sys/kern/kern_lwp.c | 32 +++++++++++++++++----------
sys/kern/kern_resource.c | 6 ++--
sys/kern/kern_sleepq.c | 6 ++--
sys/kern/kern_softint.c | 10 ++++----
sys/kern/kern_synch.c | 39 ++++++++++++++++++++--------------
sys/rump/librump/rumpkern/lwproc.c | 12 +++++-----
sys/rump/librump/rumpkern/scheduler.c | 6 ++--
sys/sys/lwp.h | 21 ++++++++++++++----
13 files changed, 98 insertions(+), 75 deletions(-)
diffs (truncated from 607 to 300 lines):
diff -r 1ec729ccb21e -r 8c8d23a1cb87 sys/arch/vax/vax/pmap.c
--- a/sys/arch/vax/vax/pmap.c Sat Feb 15 17:14:30 2020 +0000
+++ b/sys/arch/vax/vax/pmap.c Sat Feb 15 18:12:14 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: pmap.c,v 1.188 2020/01/08 17:38:42 ad Exp $ */
+/* $NetBSD: pmap.c,v 1.189 2020/02/15 18:12:14 ad Exp $ */
/*
* Copyright (c) 1994, 1998, 1999, 2003 Ludd, University of Lule}, Sweden.
* All rights reserved.
@@ -25,7 +25,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.188 2020/01/08 17:38:42 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.189 2020/02/15 18:12:14 ad Exp $");
#include "opt_ddb.h"
#include "opt_cputype.h"
@@ -699,7 +699,7 @@
return false;
if (l->l_proc->p_vmspace->vm_map.pmap == pm)
return false;
- if ((l->l_flag & LW_RUNNING) != 0)
+ if ((l->l_pflag & LP_RUNNING) != 0)
return false;
if (l->l_class != SCHED_OTHER)
return false;
diff -r 1ec729ccb21e -r 8c8d23a1cb87 sys/ddb/db_proc.c
--- a/sys/ddb/db_proc.c Sat Feb 15 17:14:30 2020 +0000
+++ b/sys/ddb/db_proc.c Sat Feb 15 18:12:14 2020 +0000
@@ -1,7 +1,7 @@
-/* $NetBSD: db_proc.c,v 1.9 2020/01/08 17:38:42 ad Exp $ */
+/* $NetBSD: db_proc.c,v 1.10 2020/02/15 18:12:14 ad Exp $ */
/*-
- * Copyright (c) 2009 The NetBSD Foundation, Inc.
+ * Copyright (c) 2009, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -61,7 +61,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: db_proc.c,v 1.9 2020/01/08 17:38:42 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: db_proc.c,v 1.10 2020/02/15 18:12:14 ad Exp $");
#ifndef _KERNEL
#include <stdbool.h>
@@ -196,7 +196,7 @@
sizeof(db_nbuf));
}
run = (l.l_stat == LSONPROC ||
- (l.l_flag & LW_RUNNING) != 0);
+ (l.l_pflag & LP_RUNNING) != 0);
if (l.l_cpu != NULL) {
db_read_bytes((db_addr_t)
&l.l_cpu->ci_data.cpu_index,
@@ -254,7 +254,7 @@
wbuf[0] = '\0';
}
run = (l.l_stat == LSONPROC ||
- (l.l_flag & LW_RUNNING) != 0);
+ (l.l_pflag & LP_RUNNING) != 0);
db_read_bytes((db_addr_t)&p.p_emul->e_name,
sizeof(ename), (char *)&ename);
@@ -332,7 +332,7 @@
db_read_bytes((db_addr_t)lp, sizeof(l), (char *)&l);
run = (l.l_stat == LSONPROC ||
- (l.l_flag & LW_RUNNING) != 0);
+ (l.l_pflag & LP_RUNNING) != 0);
db_printf("%slwp %d", (run ? "> " : " "), l.l_lid);
if (l.l_name != NULL) {
diff -r 1ec729ccb21e -r 8c8d23a1cb87 sys/kern/init_main.c
--- a/sys/kern/init_main.c Sat Feb 15 17:14:30 2020 +0000
+++ b/sys/kern/init_main.c Sat Feb 15 18:12:14 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: init_main.c,v 1.519 2020/01/28 16:35:39 ad Exp $ */
+/* $NetBSD: init_main.c,v 1.520 2020/02/15 18:12:15 ad Exp $ */
/*-
* Copyright (c) 2008, 2009, 2019 The NetBSD Foundation, Inc.
@@ -97,7 +97,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.519 2020/01/28 16:35:39 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.520 2020/02/15 18:12:15 ad Exp $");
#include "opt_ddb.h"
#include "opt_inet.h"
@@ -290,7 +290,7 @@
#ifndef LWP0_CPU_INFO
l->l_cpu = curcpu();
#endif
- l->l_flag |= LW_RUNNING;
+ l->l_pflag |= LP_RUNNING;
/*
* Attempt to find console and initialize
diff -r 1ec729ccb21e -r 8c8d23a1cb87 sys/kern/kern_exit.c
--- a/sys/kern/kern_exit.c Sat Feb 15 17:14:30 2020 +0000
+++ b/sys/kern/kern_exit.c Sat Feb 15 18:12:14 2020 +0000
@@ -1,7 +1,7 @@
-/* $NetBSD: kern_exit.c,v 1.282 2020/01/29 15:47:52 ad Exp $ */
+/* $NetBSD: kern_exit.c,v 1.283 2020/02/15 18:12:15 ad Exp $ */
/*-
- * Copyright (c) 1998, 1999, 2006, 2007, 2008 The NetBSD Foundation, Inc.
+ * Copyright (c) 1998, 1999, 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -67,7 +67,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.282 2020/01/29 15:47:52 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.283 2020/02/15 18:12:15 ad Exp $");
#include "opt_ktrace.h"
#include "opt_dtrace.h"
@@ -592,9 +592,6 @@
*/
cpu_lwp_free(l, 1);
- /* For the LW_RUNNING check in lwp_free(). */
- membar_exit();
-
/* Switch away into oblivion. */
lwp_lock(l);
spc_lock(l->l_cpu);
diff -r 1ec729ccb21e -r 8c8d23a1cb87 sys/kern/kern_idle.c
--- a/sys/kern/kern_idle.c Sat Feb 15 17:14:30 2020 +0000
+++ b/sys/kern/kern_idle.c Sat Feb 15 18:12:14 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_idle.c,v 1.31 2020/01/25 20:29:43 ad Exp $ */
+/* $NetBSD: kern_idle.c,v 1.32 2020/02/15 18:12:15 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 1.31 2020/01/25 20:29:43 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_idle.c,v 1.32 2020/02/15 18:12:15 ad Exp $");
#include <sys/param.h>
#include <sys/cpu.h>
@@ -57,7 +57,7 @@
binuptime(&l->l_stime);
spc->spc_flags |= SPCF_RUNNING;
KASSERT(l->l_stat == LSONPROC);
- KASSERT((l->l_flag & LW_RUNNING) != 0);
+ KASSERT((l->l_pflag & LP_RUNNING) != 0);
lwp_unlock(l);
/*
@@ -120,7 +120,7 @@
* takes an interrupt before it calls idle_loop().
*/
l->l_stat = LSONPROC;
- l->l_flag |= LW_RUNNING;
+ l->l_pflag |= LP_RUNNING;
ci->ci_onproc = l;
}
lwp_unlock(l);
diff -r 1ec729ccb21e -r 8c8d23a1cb87 sys/kern/kern_lwp.c
--- a/sys/kern/kern_lwp.c Sat Feb 15 17:14:30 2020 +0000
+++ b/sys/kern/kern_lwp.c Sat Feb 15 18:12:14 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_lwp.c,v 1.226 2020/02/15 17:13:55 ad Exp $ */
+/* $NetBSD: kern_lwp.c,v 1.227 2020/02/15 18:12:15 ad Exp $ */
/*-
* Copyright (c) 2001, 2006, 2007, 2008, 2009, 2019, 2020
@@ -80,7 +80,7 @@
* LWP. The LWP may in fact be executing on a processor, may be
* sleeping or idle. It is expected to take the necessary action to
* stop executing or become "running" again within a short timeframe.
- * The LW_RUNNING flag in lwp::l_flag indicates that an LWP is running.
+ * The LP_RUNNING flag in lwp::l_pflag indicates that an LWP is running.
* Importantly, it indicates that its state is tied to a CPU.
*
* LSZOMB:
@@ -211,7 +211,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.226 2020/02/15 17:13:55 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.227 2020/02/15 18:12:15 ad Exp $");
#include "opt_ddb.h"
#include "opt_lockdebug.h"
@@ -1044,16 +1044,26 @@
void
lwp_startup(struct lwp *prev, struct lwp *new_lwp)
{
+ kmutex_t *lock;
KASSERTMSG(new_lwp == curlwp, "l %p curlwp %p prevlwp %p", new_lwp, curlwp, prev);
KASSERT(kpreempt_disabled());
KASSERT(prev != NULL);
- KASSERT((prev->l_flag & LW_RUNNING) != 0);
+ KASSERT((prev->l_pflag & LP_RUNNING) != 0);
KASSERT(curcpu()->ci_mtx_count == -2);
- /* Immediately mark previous LWP as no longer running, and unlock. */
- prev->l_flag &= ~LW_RUNNING;
- lwp_unlock(prev);
+ /*
+ * Immediately mark the previous LWP as no longer running and unlock
+ * (to keep lock wait times short as possible). If a zombie, don't
+ * touch after clearing LP_RUNNING as it could be reaped by another
+ * CPU. Issue a memory barrier to ensure this.
+ */
+ lock = prev->l_mutex;
+ if (__predict_false(prev->l_stat == LSZOMB)) {
+ membar_sync();
+ }
+ prev->l_pflag &= ~LP_RUNNING;
+ mutex_spin_exit(lock);
/* Correct spin mutex count after mi_switch(). */
curcpu()->ci_mtx_count = 0;
@@ -1224,8 +1234,6 @@
cpu_lwp_free(l, 0);
if (current) {
- /* For the LW_RUNNING check in lwp_free(). */
- membar_exit();
/* Switch away into oblivion. */
lwp_lock(l);
spc_lock(l->l_cpu);
@@ -1304,8 +1312,8 @@
* all locks to avoid deadlock against interrupt handlers on
* the target CPU.
*/
- membar_enter();
- while (__predict_false((l->l_flag & LW_RUNNING) != 0)) {
+ membar_consumer();
+ while (__predict_false((l->l_pflag & LP_RUNNING) != 0)) {
SPINLOCK_BACKOFF_HOOK;
}
#endif
@@ -1371,7 +1379,7 @@
KASSERT(tci != NULL);
/* If LWP is still on the CPU, it must be handled like LSONPROC */
- if ((l->l_flag & LW_RUNNING) != 0) {
+ if ((l->l_pflag & LP_RUNNING) != 0) {
lstat = LSONPROC;
}
diff -r 1ec729ccb21e -r 8c8d23a1cb87 sys/kern/kern_resource.c
--- a/sys/kern/kern_resource.c Sat Feb 15 17:14:30 2020 +0000
+++ b/sys/kern/kern_resource.c Sat Feb 15 18:12:14 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_resource.c,v 1.184 2020/01/08 17:38:42 ad Exp $ */
+/* $NetBSD: kern_resource.c,v 1.185 2020/02/15 18:12:15 ad Exp $ */
/*-
* Copyright (c) 1982, 1986, 1991, 1993
@@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_resource.c,v 1.184 2020/01/08 17:38:42 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_resource.c,v 1.185 2020/02/15 18:12:15 ad Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -506,7 +506,7 @@
LIST_FOREACH(l, &p->p_lwps, l_sibling) {
lwp_lock(l);
bintime_add(&tm, &l->l_rtime);
- if ((l->l_flag & LW_RUNNING) != 0 &&
+ if ((l->l_pflag & LP_RUNNING) != 0 &&
(l->l_pflag & (LP_INTR | LP_TIMEINTR)) != LP_INTR) {
struct bintime diff;
/*
diff -r 1ec729ccb21e -r 8c8d23a1cb87 sys/kern/kern_sleepq.c
--- a/sys/kern/kern_sleepq.c Sat Feb 15 17:14:30 2020 +0000
+++ b/sys/kern/kern_sleepq.c Sat Feb 15 18:12:14 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_sleepq.c,v 1.60 2020/02/01 19:29:27 christos Exp $ */
+/* $NetBSD: kern_sleepq.c,v 1.61 2020/02/15 18:12:15 ad Exp $ */
/*-
* Copyright (c) 2006, 2007, 2008, 2009, 2019, 2020 The NetBSD Foundation, Inc.
@@ -35,7 +35,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_sleepq.c,v 1.60 2020/02/01 19:29:27 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_sleepq.c,v 1.61 2020/02/15 18:12:15 ad Exp $");
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