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Fix the locking against oneself, migrate LWPs only from runqueue.

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Part of the fix for PR/38882.
This commit is contained in:
rmind 2008-07-14 01:27:15 +00:00
parent 4f91cff093
commit 7c330ba82f
1 changed files with 14 additions and 9 deletions
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23
sys/kern/kern_cpu.c
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@ -1,4 +1,4 @@
/* $NetBSD: kern_cpu.c,v 1.33 2008/06/22 13:59:06 ad Exp $ */
/* $NetBSD: kern_cpu.c,v 1.34 2008/07/14 01:27:15 rmind Exp $ */
/*-
* Copyright (c) 2007, 2008 The NetBSD Foundation, Inc.
@ -57,7 +57,7 @@
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_cpu.c,v 1.33 2008/06/22 13:59:06 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: kern_cpu.c,v 1.34 2008/07/14 01:27:15 rmind Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -275,19 +275,24 @@ cpu_xc_offline(struct cpu_info *ci)
mutex_enter(proc_lock);
spc_dlock(ci, mci);
LIST_FOREACH(l, &alllwp, l_list) {
lwp_lock(l);
if (l->l_cpu != ci || (l->l_pflag & LP_BOUND) != 0) {
lwp_unlock(l);
/*
* Since runqueues are locked - LWPs cannot be enqueued (and
* cannot change the state), thus is safe to perform the
* checks without locking each LWP.
*/
if (l->l_cpu != ci || (l->l_pflag & LP_BOUND) != 0 ||
l->l_stat != LSRUN)
continue;
}
if (l->l_stat == LSRUN && (l->l_flag & LW_INMEM) != 0) {
/* At this point, we are sure about the state of LWP */
KASSERT(lwp_locked(l, spc->spc_mutex));
if ((l->l_flag & LW_INMEM) != 0) {
sched_dequeue(l);
l->l_cpu = mci;
lwp_setlock(l, mspc->spc_mutex);
sched_enqueue(l, false);
lwp_unlock(l);
} else {
lwp_migrate(l, mci);
l->l_cpu = mci;
lwp_setlock(l, mspc->spc_mutex);
}
}
spc_dunlock(ci, mci);