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/* Changing pager attributes synchronously
Copyright (C) 1994, 1996 Free Software Foundation
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "priv.h"
#include <assert.h>
/* Change the attributes of the memory object underlying pager P.
Arguments MAY_CACHE and COPY_STRATEGY are as for
memory_object_change_attributes. Wait for the kernel to report
completion if WAIT is set. */
void
pager_change_attributes (struct pager *p,
boolean_t may_cache,
memory_object_copy_strategy_t copy_strategy,
int wait)
{
struct attribute_request *ar = 0;
pthread_mutex_lock (&p->interlock);
/* If there's nothing to do we might be able to return. However,
if the user asked us to wait, and there are pending changes,
then we have to do the work anyway because we must follow the
pending change. */
if (p->may_cache == may_cache && p->copy_strategy == copy_strategy
&& ! (p->attribute_requests && wait))
{
pthread_mutex_unlock (&p->interlock);
return;
}
p->may_cache = may_cache;
p->copy_strategy = copy_strategy;
if (p->pager_state == NOTINIT)
{
pthread_mutex_unlock (&p->interlock);
return;
}
if (wait)
{
for (ar = p->attribute_requests; ar; ar = ar->next)
if (ar->may_cache == may_cache
&& ar->copy_strategy == copy_strategy)
{
ar->attrs_pending++;
ar->threads_waiting++;
break;
}
if (!ar)
{
ar = malloc (sizeof (struct attribute_request));
ar->may_cache = may_cache;
ar->copy_strategy = copy_strategy;
ar->attrs_pending = 1;
ar->threads_waiting = 1;
ar->next = p->attribute_requests;
if (ar->next)
ar->next->prevp = &ar->next;
ar->prevp = &p->attribute_requests;
p->attribute_requests = ar;
}
}
pthread_mutex_unlock (&p->interlock);
memory_object_change_attributes (p->memobjcntl, may_cache, copy_strategy,
wait ? p->port.port_right : MACH_PORT_NULL);
if (wait)
{
pthread_mutex_lock (&p->interlock);
while (ar->attrs_pending)
pthread_cond_wait (&p->wakeup, &p->interlock);
if (! --ar->threads_waiting)
{
*ar->prevp = ar->next;
if (ar->next)
ar->next->prevp = ar->prevp;
free (ar);
}
pthread_mutex_unlock (&p->interlock);
}
}
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