The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/uvm/uvm_object.c

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    1 /*      $NetBSD: uvm_object.c,v 1.2 2006/10/12 10:13:35 yamt Exp $      */
    2 
    3 /*
    4  * Copyright (c) 2006 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. All advertising materials mentioning features or use of this software
   16  *    must display the following acknowledgement:
   17  *      This product includes software developed by the NetBSD
   18  *      Foundation, Inc. and its contributors.
   19  * 4. Neither the name of The NetBSD Foundation nor the names of its
   20  *    contributors may be used to endorse or promote products derived
   21  *    from this software without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   24  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   25  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   26  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   27  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   28  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   29  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   30  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   31  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   32  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   33  * POSSIBILITY OF SUCH DAMAGE.
   34  */
   35 
   36 /*
   37  * uvm_object.c: operate with memory objects
   38  *
   39  * TODO:
   40  *  1. Support PG_RELEASED-using objects
   41  *
   42  */
   43 
   44 #include <sys/cdefs.h>
   45 __KERNEL_RCSID(0, "$NetBSD: uvm_object.c,v 1.2 2006/10/12 10:13:35 yamt Exp $");
   46 
   47 #include "opt_uvmhist.h"
   48 
   49 #include <sys/param.h>
   50 #include <sys/lock.h>
   51 
   52 #include <uvm/uvm.h>
   53 
   54 /* We will fetch this page count per step */
   55 #define FETCH_PAGECOUNT 16
   56 
   57 /*
   58  * uobj_wirepages: wire the pages of entire uobj
   59  *
   60  * => NOTE: this function should only be used for types of objects
   61  *  where PG_RELEASED flag is never set (aobj objects)
   62  * => caller must pass page-aligned start and end values
   63  */
   64 
   65 int
   66 uobj_wirepages(struct uvm_object *uobj, off_t start, off_t end)
   67 {
   68         int i, npages, error;
   69         struct vm_page *pgs[FETCH_PAGECOUNT], *pg = NULL;
   70         off_t offset = start, left;
   71 
   72         left = (end - start) >> PAGE_SHIFT;
   73 
   74         simple_lock(&uobj->vmobjlock);
   75         while (left) {
   76 
   77                 npages = MIN(FETCH_PAGECOUNT, left);
   78 
   79                 /* Get the pages */
   80                 memset(pgs, 0, sizeof(pgs));
   81                 error = (*uobj->pgops->pgo_get)(uobj, offset, pgs, &npages, 0,
   82                         VM_PROT_READ | VM_PROT_WRITE, UVM_ADV_SEQUENTIAL,
   83                         PGO_ALLPAGES | PGO_SYNCIO);
   84 
   85                 if (error)
   86                         goto error;
   87 
   88                 simple_lock(&uobj->vmobjlock);
   89                 for (i = 0; i < npages; i++) {
   90 
   91                         KASSERT(pgs[i] != NULL);
   92                         KASSERT(!(pgs[i]->flags & PG_RELEASED));
   93 
   94                         /*
   95                          * Loan break
   96                          */
   97                         if (pgs[i]->loan_count) {
   98                                 while (pgs[i]->loan_count) {
   99                                         pg = uvm_loanbreak(pgs[i]);
  100                                         if (!pg) {
  101                                                 simple_unlock(&uobj->vmobjlock);
  102                                                 uvm_wait("uobjwirepg");
  103                                                 simple_lock(&uobj->vmobjlock);
  104                                                 continue;
  105                                         }
  106                                 }
  107                                 pgs[i] = pg;
  108                         }
  109 
  110                         if (pgs[i]->pqflags & PQ_AOBJ) {
  111                                 pgs[i]->flags &= ~(PG_CLEAN);
  112                                 uao_dropswap(uobj, i);
  113                         }
  114                 }
  115 
  116                 /* Wire the pages */
  117                 uvm_lock_pageq();
  118                 for (i = 0; i < npages; i++) {
  119                         uvm_pagewire(pgs[i]);
  120                 }
  121                 uvm_unlock_pageq();
  122 
  123                 /* Unbusy the pages */
  124                 uvm_page_unbusy(pgs, npages);
  125 
  126                 left -= npages;
  127                 offset += npages << PAGE_SHIFT;
  128         }
  129         simple_unlock(&uobj->vmobjlock);
  130 
  131         return 0;
  132 
  133 error:
  134         /* Unwire the pages which has been wired */
  135         uobj_unwirepages(uobj, start, offset);
  136 
  137         return error;
  138 }
  139 
  140 /*
  141  * uobj_unwirepages: unwire the pages of entire uobj
  142  *
  143  * => NOTE: this function should only be used for types of objects
  144  *  where PG_RELEASED flag is never set
  145  * => caller must pass page-aligned start and end values
  146  */
  147 
  148 void
  149 uobj_unwirepages(struct uvm_object *uobj, off_t start, off_t end)
  150 {
  151         struct vm_page *pg;
  152         off_t offset;
  153 
  154         simple_lock(&uobj->vmobjlock);
  155         uvm_lock_pageq();
  156         for (offset = start; offset < end; offset += PAGE_SIZE) {
  157                 pg = uvm_pagelookup(uobj, offset);
  158 
  159                 KASSERT(pg != NULL);
  160                 KASSERT(!(pg->flags & PG_RELEASED));
  161 
  162                 uvm_pageunwire(pg);
  163         }
  164         uvm_unlock_pageq();
  165         simple_unlock(&uobj->vmobjlock);
  166 }

Cache object: 72a3006afa40b44ad0dfe1ecd07105d3


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