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43ab9660c5
in devfs if a particular race condition is hit in the device pager code. This was a side effect of change 227530 which changed the device pager interface to call a new destructor routine for the cdev. That destructor routine, old_dev_pager_dtor(), takes a VM object handle. The object handle is cast to a struct cdev *, and passed into dev_rel(). That works in most cases, except the case in cdev_pager_allocate() where there is a race condition between two threads allocating an object backed by the same device. The loser of the race deallocates its object at the end of the function. The problem is that before inserting the object into the dev_pager_object_list, the object's handle is changed from the struct cdev pointer to the object's own address. This is to avoid conflicts with the winner of the race, which already inserted an object in the list with a handle that is a pointer to the same cdev structure. The object is then passed to vm_object_deallocate(), and eventually makes its way down to old_dev_pager_dtor(). That function passes the handle pointer (which is actually a VM object, not a struct cdev as usual) into dev_rel(). dev_rel() decrements the reference count in the assumed struct cdev (which happens to be 0), and that triggers the assertion in dev_rel() that the reference count is greater than or equal to 0. The fix is to add a cdev pointer to the VM object, and use that pointer when calling the cdev_pg_dtor() routine. vm_object.h: Add a struct cdev pointer to the VM object structure. device_pager.c: In cdev_pager_allocate(), populate the new cdev pointer. In dev_pager_dealloc(), use the new cdev pointer when calling the object's cdev_pg_dtor() routine. Reviewed by: kib Sponsored by: Spectra Logic Corporation MFC after: 1 week
432 lines
11 KiB
C
432 lines
11 KiB
C
/*-
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* Copyright (c) 1990 University of Utah.
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* the Systems Programming Group of the University of Utah Computer
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* Science Department.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)device_pager.c 8.1 (Berkeley) 6/11/93
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/conf.h>
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#include <sys/lock.h>
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#include <sys/proc.h>
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#include <sys/mutex.h>
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#include <sys/mman.h>
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#include <sys/sx.h>
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/vm_object.h>
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#include <vm/vm_page.h>
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#include <vm/vm_pager.h>
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#include <vm/vm_phys.h>
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#include <vm/uma.h>
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static void dev_pager_init(void);
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static vm_object_t dev_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
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vm_ooffset_t, struct ucred *);
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static void dev_pager_dealloc(vm_object_t);
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static int dev_pager_getpages(vm_object_t, vm_page_t *, int, int);
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static void dev_pager_putpages(vm_object_t, vm_page_t *, int,
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boolean_t, int *);
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static boolean_t dev_pager_haspage(vm_object_t, vm_pindex_t, int *,
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int *);
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static void dev_pager_free_page(vm_object_t object, vm_page_t m);
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/* list of device pager objects */
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static struct pagerlst dev_pager_object_list;
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/* protect list manipulation */
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static struct mtx dev_pager_mtx;
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struct pagerops devicepagerops = {
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.pgo_init = dev_pager_init,
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.pgo_alloc = dev_pager_alloc,
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.pgo_dealloc = dev_pager_dealloc,
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.pgo_getpages = dev_pager_getpages,
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.pgo_putpages = dev_pager_putpages,
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.pgo_haspage = dev_pager_haspage,
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};
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struct pagerops mgtdevicepagerops = {
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.pgo_alloc = dev_pager_alloc,
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.pgo_dealloc = dev_pager_dealloc,
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.pgo_getpages = dev_pager_getpages,
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.pgo_putpages = dev_pager_putpages,
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.pgo_haspage = dev_pager_haspage,
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};
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static int old_dev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
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vm_ooffset_t foff, struct ucred *cred, u_short *color);
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static void old_dev_pager_dtor(void *handle);
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static int old_dev_pager_fault(vm_object_t object, vm_ooffset_t offset,
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int prot, vm_page_t *mres);
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static struct cdev_pager_ops old_dev_pager_ops = {
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.cdev_pg_ctor = old_dev_pager_ctor,
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.cdev_pg_dtor = old_dev_pager_dtor,
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.cdev_pg_fault = old_dev_pager_fault
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};
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static void
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dev_pager_init()
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{
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TAILQ_INIT(&dev_pager_object_list);
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mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
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}
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vm_object_t
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cdev_pager_lookup(void *handle)
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{
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vm_object_t object;
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mtx_lock(&dev_pager_mtx);
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object = vm_pager_object_lookup(&dev_pager_object_list, handle);
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mtx_unlock(&dev_pager_mtx);
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return (object);
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}
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vm_object_t
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cdev_pager_allocate(void *handle, enum obj_type tp, struct cdev_pager_ops *ops,
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vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff, struct ucred *cred)
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{
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vm_object_t object, object1;
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vm_pindex_t pindex;
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u_short color;
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if (tp != OBJT_DEVICE && tp != OBJT_MGTDEVICE)
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return (NULL);
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/*
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* Offset should be page aligned.
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*/
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if (foff & PAGE_MASK)
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return (NULL);
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size = round_page(size);
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pindex = OFF_TO_IDX(foff + size);
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if (ops->cdev_pg_ctor(handle, size, prot, foff, cred, &color) != 0)
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return (NULL);
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mtx_lock(&dev_pager_mtx);
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/*
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* Look up pager, creating as necessary.
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*/
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object1 = NULL;
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object = vm_pager_object_lookup(&dev_pager_object_list, handle);
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if (object == NULL) {
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/*
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* Allocate object and associate it with the pager. Initialize
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* the object's pg_color based upon the physical address of the
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* device's memory.
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*/
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mtx_unlock(&dev_pager_mtx);
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object1 = vm_object_allocate(tp, pindex);
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object1->flags |= OBJ_COLORED;
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object1->pg_color = color;
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object1->handle = handle;
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object1->un_pager.devp.ops = ops;
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object1->un_pager.devp.dev = handle;
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TAILQ_INIT(&object1->un_pager.devp.devp_pglist);
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mtx_lock(&dev_pager_mtx);
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object = vm_pager_object_lookup(&dev_pager_object_list, handle);
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if (object != NULL) {
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/*
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* We raced with other thread while allocating object.
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*/
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if (pindex > object->size)
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object->size = pindex;
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} else {
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object = object1;
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object1 = NULL;
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object->handle = handle;
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TAILQ_INSERT_TAIL(&dev_pager_object_list, object,
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pager_object_list);
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KASSERT(object->type == tp,
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("Inconsistent device pager type %p %d", object, tp));
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}
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} else {
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if (pindex > object->size)
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object->size = pindex;
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}
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mtx_unlock(&dev_pager_mtx);
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if (object1 != NULL) {
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object1->handle = object1;
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mtx_lock(&dev_pager_mtx);
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TAILQ_INSERT_TAIL(&dev_pager_object_list, object1,
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pager_object_list);
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mtx_unlock(&dev_pager_mtx);
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vm_object_deallocate(object1);
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}
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return (object);
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}
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static vm_object_t
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dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
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vm_ooffset_t foff, struct ucred *cred)
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{
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return (cdev_pager_allocate(handle, OBJT_DEVICE, &old_dev_pager_ops,
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size, prot, foff, cred));
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}
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void
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cdev_pager_free_page(vm_object_t object, vm_page_t m)
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{
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VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
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if (object->type == OBJT_MGTDEVICE) {
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KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("unmanaged %p", m));
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pmap_remove_all(m);
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vm_page_lock(m);
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vm_page_remove(m);
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vm_page_unlock(m);
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} else if (object->type == OBJT_DEVICE)
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dev_pager_free_page(object, m);
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}
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static void
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dev_pager_free_page(vm_object_t object, vm_page_t m)
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{
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VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
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KASSERT((object->type == OBJT_DEVICE &&
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(m->oflags & VPO_UNMANAGED) != 0),
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("Managed device or page obj %p m %p", object, m));
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TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
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vm_page_putfake(m);
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}
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static void
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dev_pager_dealloc(object)
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vm_object_t object;
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{
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vm_page_t m;
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VM_OBJECT_UNLOCK(object);
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object->un_pager.devp.ops->cdev_pg_dtor(object->un_pager.devp.dev);
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mtx_lock(&dev_pager_mtx);
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TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
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mtx_unlock(&dev_pager_mtx);
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VM_OBJECT_LOCK(object);
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if (object->type == OBJT_DEVICE) {
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/*
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* Free up our fake pages.
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*/
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while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist))
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!= NULL)
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dev_pager_free_page(object, m);
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}
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}
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static int
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dev_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int reqpage)
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{
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int error, i;
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VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
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error = object->un_pager.devp.ops->cdev_pg_fault(object,
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IDX_TO_OFF(ma[reqpage]->pindex), PROT_READ, &ma[reqpage]);
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VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
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for (i = 0; i < count; i++) {
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if (i != reqpage) {
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vm_page_lock(ma[i]);
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vm_page_free(ma[i]);
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vm_page_unlock(ma[i]);
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}
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}
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if (error == VM_PAGER_OK) {
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KASSERT((object->type == OBJT_DEVICE &&
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(ma[reqpage]->oflags & VPO_UNMANAGED) != 0) ||
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(object->type == OBJT_MGTDEVICE &&
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(ma[reqpage]->oflags & VPO_UNMANAGED) == 0),
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("Wrong page type %p %p", ma[reqpage], object));
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if (object->type == OBJT_DEVICE) {
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TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist,
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ma[reqpage], pageq);
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}
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}
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return (error);
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}
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static int
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old_dev_pager_fault(vm_object_t object, vm_ooffset_t offset, int prot,
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vm_page_t *mres)
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{
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vm_pindex_t pidx;
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vm_paddr_t paddr;
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vm_page_t m_paddr, page;
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struct cdev *dev;
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struct cdevsw *csw;
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struct file *fpop;
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struct thread *td;
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vm_memattr_t memattr;
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int ref, ret;
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pidx = OFF_TO_IDX(offset);
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memattr = object->memattr;
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VM_OBJECT_UNLOCK(object);
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dev = object->handle;
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csw = dev_refthread(dev, &ref);
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if (csw == NULL) {
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VM_OBJECT_LOCK(object);
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return (VM_PAGER_FAIL);
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}
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td = curthread;
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fpop = td->td_fpop;
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td->td_fpop = NULL;
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ret = csw->d_mmap(dev, offset, &paddr, prot, &memattr);
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td->td_fpop = fpop;
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dev_relthread(dev, ref);
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if (ret != 0) {
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printf(
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"WARNING: dev_pager_getpage: map function returns error %d", ret);
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VM_OBJECT_LOCK(object);
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return (VM_PAGER_FAIL);
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}
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/* If "paddr" is a real page, perform a sanity check on "memattr". */
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if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
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pmap_page_get_memattr(m_paddr) != memattr) {
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memattr = pmap_page_get_memattr(m_paddr);
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printf(
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"WARNING: A device driver has set \"memattr\" inconsistently.\n");
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}
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if (((*mres)->flags & PG_FICTITIOUS) != 0) {
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/*
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* If the passed in result page is a fake page, update it with
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* the new physical address.
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*/
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page = *mres;
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VM_OBJECT_LOCK(object);
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vm_page_updatefake(page, paddr, memattr);
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} else {
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/*
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* Replace the passed in reqpage page with our own fake page and
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* free up the all of the original pages.
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*/
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page = vm_page_getfake(paddr, memattr);
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VM_OBJECT_LOCK(object);
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vm_page_lock(*mres);
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vm_page_free(*mres);
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vm_page_unlock(*mres);
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*mres = page;
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vm_page_insert(page, object, pidx);
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}
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page->valid = VM_PAGE_BITS_ALL;
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return (VM_PAGER_OK);
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}
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static void
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dev_pager_putpages(object, m, count, sync, rtvals)
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vm_object_t object;
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vm_page_t *m;
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int count;
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boolean_t sync;
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int *rtvals;
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{
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panic("dev_pager_putpage called");
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}
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static boolean_t
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dev_pager_haspage(object, pindex, before, after)
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vm_object_t object;
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vm_pindex_t pindex;
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int *before;
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int *after;
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{
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if (before != NULL)
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*before = 0;
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if (after != NULL)
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*after = 0;
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return (TRUE);
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}
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static int
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old_dev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
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vm_ooffset_t foff, struct ucred *cred, u_short *color)
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{
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struct cdev *dev;
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struct cdevsw *csw;
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vm_memattr_t dummy;
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vm_ooffset_t off;
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vm_paddr_t paddr;
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unsigned int npages;
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int ref;
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/*
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* Make sure this device can be mapped.
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*/
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dev = handle;
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csw = dev_refthread(dev, &ref);
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if (csw == NULL)
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return (ENXIO);
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/*
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* Check that the specified range of the device allows the desired
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* protection.
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*
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* XXX assumes VM_PROT_* == PROT_*
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*/
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npages = OFF_TO_IDX(size);
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for (off = foff; npages--; off += PAGE_SIZE) {
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if (csw->d_mmap(dev, off, &paddr, (int)prot, &dummy) != 0) {
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dev_relthread(dev, ref);
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return (EINVAL);
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}
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}
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dev_ref(dev);
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dev_relthread(dev, ref);
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*color = atop(paddr) - OFF_TO_IDX(off - PAGE_SIZE);
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return (0);
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}
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static void
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old_dev_pager_dtor(void *handle)
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{
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dev_rel(handle);
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}
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