[src/trunk]: src/sys/uvm Add amap_adjref_anons() helper and simplify amap_ref...

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

details:   https://anonhg.NetBSD.org/src/rev/8c724c635ffa
branches:  trunk
changeset: 766203:8c724c635ffa
user:      rmind <rmind%NetBSD.org@localhost>
date:      Sat Jun 18 20:29:56 2011 +0000

description:
Add amap_adjref_anons() helper and simplify amap_ref()/amap_unref().

diffstat:

 sys/uvm/uvm_amap.c |  111 ++++++++++++++++++++++++----------------------------
 1 files changed, 52 insertions(+), 59 deletions(-)

diffs (165 lines):

diff -r db8de2a3a18d -r 8c724c635ffa sys/uvm/uvm_amap.c
--- a/sys/uvm/uvm_amap.c        Sat Jun 18 20:28:48 2011 +0000
+++ b/sys/uvm/uvm_amap.c        Sat Jun 18 20:29:56 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_amap.c,v 1.92 2011/06/16 19:42:20 rmind Exp $      */
+/*     $NetBSD: uvm_amap.c,v 1.93 2011/06/18 20:29:56 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 1.92 2011/06/16 19:42:20 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_amap.c,v 1.93 2011/06/18 20:29:56 rmind Exp $");
 
 #include "opt_uvmhist.h"
 
@@ -1525,96 +1525,89 @@
 }
 
 /*
- * amap_ref: gain a reference to an amap
+ * amap_adjref_anons: adjust the reference count(s) on anons of the amap.
+ */
+static void
+amap_adjref_anons(struct vm_amap *amap, vaddr_t offset, vsize_t len,
+    int refv, bool all)
+{
+#ifdef UVM_AMAP_PPREF
+       KASSERT(mutex_owned(amap->am_lock));
+
+       if (amap->am_ppref == NULL && !all && len != amap->am_nslot) {
+               amap_pp_establish(amap, offset);
+       }
+       if (amap->am_ppref && amap->am_ppref != PPREF_NONE) {
+               struct vm_anon *tofree = NULL;
+
+               if (all) {
+                       amap_pp_adjref(amap, 0, amap->am_nslot, refv, &tofree);
+               } else {
+                       amap_pp_adjref(amap, offset, len, refv, &tofree);
+               }
+               uvm_anfree(tofree);
+       }
+#endif
+}
+
+/*
+ * amap_ref: gain a reference to an amap.
  *
- * => amap must not be locked (we will lock)
- * => "offset" and "len" are in units of pages
- * => called at fork time to gain the child's reference
+ * => amap must not be locked (we will lock).
+ * => "offset" and "len" are in units of pages.
+ * => Called at fork time to gain the child's reference.
  */
 void
 amap_ref(struct vm_amap *amap, vaddr_t offset, vsize_t len, int flags)
 {
-
        UVMHIST_FUNC("amap_ref"); UVMHIST_CALLED(maphist);
 
        amap_lock(amap);
-       if (flags & AMAP_SHARED)
+       if (flags & AMAP_SHARED) {
                amap->am_flags |= AMAP_SHARED;
-#ifdef UVM_AMAP_PPREF
-       if (amap->am_ppref == NULL && (flags & AMAP_REFALL) == 0 &&
-           len != amap->am_nslot)
-               amap_pp_establish(amap, offset);
-#endif
+       }
        amap->am_ref++;
-#ifdef UVM_AMAP_PPREF
-       if (amap->am_ppref && amap->am_ppref != PPREF_NONE) {
-               struct vm_anon *tofree = NULL;
-               if (flags & AMAP_REFALL)
-                       amap_pp_adjref(amap, 0, amap->am_nslot, 1, &tofree);
-               else
-                       amap_pp_adjref(amap, offset, len, 1, &tofree);
-               uvm_anfree(tofree); /* must be last action before unlock */
-       }
-#endif
+       amap_adjref_anons(amap, offset, len, 1, (flags & AMAP_REFALL) != 0);
        amap_unlock(amap);
+
        UVMHIST_LOG(maphist,"<- done!  amap=0x%x", amap, 0, 0, 0);
 }
 
 /*
- * amap_unref: remove a reference to an amap
+ * amap_unref: remove a reference to an amap.
  *
- * => caller must remove all pmap-level references to this amap before
- *     dropping the reference
- * => called from uvm_unmap_detach [only]  ... note that entry is no
- *     longer part of a map
- * => amap must be unlocked (we will lock it).
+ * => All pmap-level references to this amap must be already removed.
+ * => Called from uvm_unmap_detach(); entry is already removed from the map.
+ * => We will lock amap, so it must be unlocked.
  */
 void
 amap_unref(struct vm_amap *amap, vaddr_t offset, vsize_t len, bool all)
 {
-       struct vm_anon *tofree;
-
        UVMHIST_FUNC("amap_unref"); UVMHIST_CALLED(maphist);
 
-       /*
-        * lock it
-        */
        amap_lock(amap);
+
        UVMHIST_LOG(maphist,"  amap=0x%x  refs=%d, nused=%d",
            amap, amap->am_ref, amap->am_nused, 0);
-
-       KASSERT(amap_refs(amap) > 0);
-
-       /*
-        * if we are the last reference, free the amap and return.
-        */
+       KASSERT(amap->am_ref > 0);
 
-       amap->am_ref--;
-
-       if (amap_refs(amap) == 0) {
-               amap_wipeout(amap);     /* drops final ref and frees */
+       if (--amap->am_ref == 0) {
+               /*
+                * If the last reference - wipeout and destroy the amap.
+                */
+               amap_wipeout(amap);
                UVMHIST_LOG(maphist,"<- done (was last ref)!", 0, 0, 0, 0);
-               return;                 /* no need to unlock */
+               return;
        }
 
        /*
-        * otherwise just drop the reference count(s)
+        * Otherwise, drop the reference count(s) on anons.
         */
 
-       if (amap_refs(amap) == 1 && (amap->am_flags & AMAP_SHARED) != 0)
-               amap->am_flags &= ~AMAP_SHARED; /* clear shared flag */
-       tofree = NULL;
-#ifdef UVM_AMAP_PPREF
-       if (amap->am_ppref == NULL && all == 0 && len != amap->am_nslot)
-               amap_pp_establish(amap, offset);
-       if (amap->am_ppref && amap->am_ppref != PPREF_NONE) {
-               if (all)
-                       amap_pp_adjref(amap, 0, amap->am_nslot, -1, &tofree);
-               else
-                       amap_pp_adjref(amap, offset, len, -1, &tofree);
+       if (amap->am_ref == 1 && (amap->am_flags & AMAP_SHARED) != 0) {
+               amap->am_flags &= ~AMAP_SHARED;
        }
-#endif
-       uvm_anfree(tofree);
+       amap_adjref_anons(amap, offset, len, -1, all);
        amap_unlock(amap);
 
        UVMHIST_LOG(maphist,"<- done!", 0, 0, 0, 0);