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Rather than calling xc_barrier() in lwp_dtor(), set a pre-destruct hook 

on the lwp_cache and invoke the barrier there.
This commit is contained in:
thorpej 2021-12-21 19:00:37 +00:00
parent 1af3a96973
commit 2b1ed0f85c
1 changed files with 18 additions and 10 deletions
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28
sys/kern/kern_lwp.c
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@ -1,4 +1,4 @@
/* $NetBSD: kern_lwp.c,v 1.244 2021/09/28 15:05:42 thorpej Exp $ */
/* $NetBSD: kern_lwp.c,v 1.245 2021/12/21 19:00:37 thorpej Exp $ */
/*-
* Copyright (c) 2001, 2006, 2007, 2008, 2009, 2019, 2020
@ -217,7 +217,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.244 2021/09/28 15:05:42 thorpej Exp $");
__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.245 2021/12/21 19:00:37 thorpej Exp $");
#include "opt_ddb.h"
#include "opt_lockdebug.h"
@ -262,6 +262,7 @@ struct lwplist alllwp __cacheline_aligned;
static int lwp_ctor(void *, void *, int);
static void lwp_dtor(void *, void *);
static void lwp_pre_dtor(void *);
/* DTrace proc provider probes */
SDT_PROVIDER_DEFINE(proc);
@ -341,6 +342,7 @@ lwpinit(void)
lwpinit_specificdata();
lwp_cache = pool_cache_init(sizeof(lwp_t), MIN_LWP_ALIGNMENT, 0, 0,
"lwppl", NULL, IPL_NONE, lwp_ctor, lwp_dtor, NULL);
pool_cache_setpredestruct(lwp_cache, lwp_pre_dtor);
maxlwp = cpu_maxlwp();
sysctl_kern_lwp_setup();
@ -391,23 +393,29 @@ lwp_ctor(void *arg, void *obj, int flags)
}
static void
lwp_dtor(void *arg, void *obj)
lwp_pre_dtor(void *arg __unused)
{
lwp_t *l = obj;
(void)l;
/*
* Provide a barrier to ensure that all mutex_oncpu() and rw_oncpu()
* calls will exit before memory of LWP is returned to the pool, where
* calls will exit before memory of LWPs is returned to the pool, where
* KVA of LWP structure might be freed and re-used for other purposes.
* Kernel preemption is disabled around mutex_oncpu() and rw_oncpu()
* callers, therefore cross-call to all CPUs will do the job. Also,
* the value of l->l_cpu must be still valid at this point.
* callers, therefore cross-call to all CPUs will do the job.
*
* XXX should use epoch based reclamation.
*/
KASSERT(l->l_cpu != NULL);
xc_barrier(0);
}
static void
lwp_dtor(void *arg, void *obj)
{
lwp_t *l = obj;
/*
* The value of l->l_cpu must still be valid at this point.
*/
KASSERT(l->l_cpu != NULL);
/*
* We can't return turnstile0 to the pool (it didn't come from it),