[src/trunk]: src/sys/uvm amap_add/amap_unadd: clean up slightly, use unsigned...

[rmind <rmind%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/39a73b5737e1
branches:  trunk
changeset: 766207:39a73b5737e1
user:      rmind <rmind%NetBSD.org@localhost>
date:      Sat Jun 18 20:51:22 2011 +0000

description:
amap_add/amap_unadd: clean up slightly, use unsigned, add asserts.

diffstat:

 sys/uvm/uvm_amap.c |  41 ++++++++++++++++++++++++-----------------
 1 files changed, 24 insertions(+), 17 deletions(-)

diffs (105 lines):

diff -r 2cb77c30981d -r 39a73b5737e1 sys/uvm/uvm_amap.c
--- a/sys/uvm/uvm_amap.c        Sat Jun 18 20:49:26 2011 +0000
+++ b/sys/uvm/uvm_amap.c        Sat Jun 18 20:51:22 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_amap.c,v 1.93 2011/06/18 20:29:56 rmind Exp $      */
+/*     $NetBSD: uvm_amap.c,v 1.94 2011/06/18 20:51:22 rmind Exp $      */
 
 /*
  * Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_amap.c,v 1.93 2011/06/18 20:29:56 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_amap.c,v 1.94 2011/06/18 20:51:22 rmind Exp $");
 
 #include "opt_uvmhist.h"
 
@@ -1456,34 +1456,37 @@
 }
 
 /*
- * amap_add: add (or replace) a page to an amap
+ * amap_add: add (or replace) a page to an amap.
  *
- * => caller must lock amap.
+ * => amap should be locked by caller.
+ * => anon must have the lock associated with this amap.
  */
 void
 amap_add(struct vm_aref *aref, vaddr_t offset, struct vm_anon *anon,
     bool replace)
 {
-       int slot;
        struct vm_amap *amap = aref->ar_amap;
+       u_int slot;
+
        UVMHIST_FUNC("amap_add"); UVMHIST_CALLED(maphist);
        KASSERT(mutex_owned(amap->am_lock));
+       KASSERT(anon->an_lock == amap->am_lock);
 
        AMAP_B2SLOT(slot, offset);
        slot += aref->ar_pageoff;
        KASSERT(slot < amap->am_nslot);
 
        if (replace) {
-               KASSERT(amap->am_anon[slot] != NULL);
-               if (amap->am_anon[slot]->an_page != NULL &&
-                   (amap->am_flags & AMAP_SHARED) != 0) {
-                       pmap_page_protect(amap->am_anon[slot]->an_page,
-                           VM_PROT_NONE);
+               struct vm_anon *oanon = amap->am_anon[slot];
+
+               KASSERT(oanon != NULL);
+               if (oanon->an_page && (amap->am_flags & AMAP_SHARED) != 0) {
+                       pmap_page_protect(oanon->an_page, VM_PROT_NONE);
                        /*
                         * XXX: suppose page is supposed to be wired somewhere?
                         */
                }
-       } else {   /* !replace */
+       } else {
                KASSERT(amap->am_anon[slot] == NULL);
                amap->am_bckptr[slot] = amap->am_nused;
                amap->am_slots[amap->am_nused] = slot;
@@ -1496,15 +1499,16 @@
 }
 
 /*
- * amap_unadd: remove a page from an amap
+ * amap_unadd: remove a page from an amap.
  *
- * => caller must lock amap
+ * => amap should be locked by caller.
  */
 void
 amap_unadd(struct vm_aref *aref, vaddr_t offset)
 {
-       int ptr, slot;
        struct vm_amap *amap = aref->ar_amap;
+       u_int slot, ptr, last;
+
        UVMHIST_FUNC("amap_unadd"); UVMHIST_CALLED(maphist);
        KASSERT(mutex_owned(amap->am_lock));
 
@@ -1512,13 +1516,16 @@
        slot += aref->ar_pageoff;
        KASSERT(slot < amap->am_nslot);
        KASSERT(amap->am_anon[slot] != NULL);
+       KASSERT(amap->am_anon[slot]->an_lock == amap->am_lock);
 
        amap->am_anon[slot] = NULL;
        ptr = amap->am_bckptr[slot];
 
-       if (ptr != (amap->am_nused - 1)) {      /* swap to keep slots contig? */
-               amap->am_slots[ptr] = amap->am_slots[amap->am_nused - 1];
-               amap->am_bckptr[amap->am_slots[ptr]] = ptr;     /* back link */
+       last = amap->am_nused - 1;
+       if (ptr != last) {
+               /* Move the last entry to keep the slots contiguous. */
+               amap->am_slots[ptr] = amap->am_slots[last];
+               amap->am_bckptr[amap->am_slots[ptr]] = ptr;
        }
        amap->am_nused--;
        UVMHIST_LOG(maphist, "<- done (amap=0x%x, slot=0x%x)", amap, slot,0, 0);