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Date:      Fri, 6 Sep 2013 16:53:49 +0000 (UTC)
From:      Konstantin Belousov <kib@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r255312 - head/sys/amd64/amd64
Message-ID:  <201309061653.r86GrnVd031102@svn.freebsd.org>
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Author: kib
Date: Fri Sep  6 16:53:48 2013
New Revision: 255312
URL: http://svnweb.freebsd.org/changeset/base/255312

Log:
  Only lock pvh_global_lock read-only for pmap_page_wired_mappings(),
  pmap_is_modified() and pmap_is_referenced(), same as it was done for
  pmap_ts_referenced().
  
  Consolidate identical code for pmap_is_modified() and
  pmap_is_referenced() into helper pmap_page_test_mappings().
  
  Reviewed by:	alc
  Tested by:	pho (previous version)
  Sponsored by:	The FreeBSD Foundation

Modified:
  head/sys/amd64/amd64/pmap.c

Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c	Fri Sep  6 16:48:34 2013	(r255311)
+++ head/sys/amd64/amd64/pmap.c	Fri Sep  6 16:53:48 2013	(r255312)
@@ -315,7 +315,6 @@ static void	pmap_pv_promote_pde(pmap_t p
 static void	pmap_pvh_free(struct md_page *pvh, pmap_t pmap, vm_offset_t va);
 static pv_entry_t pmap_pvh_remove(struct md_page *pvh, pmap_t pmap,
 		    vm_offset_t va);
-static int	pmap_pvh_wired_mappings(struct md_page *pvh, int count);
 
 static int pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode);
 static boolean_t pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va);
@@ -329,8 +328,6 @@ static vm_page_t pmap_enter_quick_locked
     vm_page_t m, vm_prot_t prot, vm_page_t mpte, struct rwlock **lockp);
 static void pmap_fill_ptp(pt_entry_t *firstpte, pt_entry_t newpte);
 static int pmap_insert_pt_page(pmap_t pmap, vm_page_t mpte);
-static boolean_t pmap_is_modified_pvh(struct md_page *pvh);
-static boolean_t pmap_is_referenced_pvh(struct md_page *pvh);
 static void pmap_kenter_attr(vm_offset_t va, vm_paddr_t pa, int mode);
 static vm_page_t pmap_lookup_pt_page(pmap_t pmap, vm_offset_t va);
 static void pmap_pde_attr(pd_entry_t *pde, int cache_bits);
@@ -4604,42 +4601,61 @@ pmap_page_exists_quick(pmap_t pmap, vm_p
 int
 pmap_page_wired_mappings(vm_page_t m)
 {
-	int count;
-
-	count = 0;
-	if ((m->oflags & VPO_UNMANAGED) != 0)
-		return (count);
-	rw_wlock(&pvh_global_lock);
-	count = pmap_pvh_wired_mappings(&m->md, count);
-	if ((m->flags & PG_FICTITIOUS) == 0) {
-	    count = pmap_pvh_wired_mappings(pa_to_pvh(VM_PAGE_TO_PHYS(m)),
-	        count);
-	}
-	rw_wunlock(&pvh_global_lock);
-	return (count);
-}
-
-/*
- *	pmap_pvh_wired_mappings:
- *
- *	Return the updated number "count" of managed mappings that are wired.
- */
-static int
-pmap_pvh_wired_mappings(struct md_page *pvh, int count)
-{
+	struct rwlock *lock;
+	struct md_page *pvh;
 	pmap_t pmap;
 	pt_entry_t *pte;
 	pv_entry_t pv;
+	int count, md_gen, pvh_gen;
 
-	rw_assert(&pvh_global_lock, RA_WLOCKED);
-	TAILQ_FOREACH(pv, &pvh->pv_list, pv_next) {
+	if ((m->oflags & VPO_UNMANAGED) != 0)
+		return (0);
+	rw_rlock(&pvh_global_lock);
+	lock = VM_PAGE_TO_PV_LIST_LOCK(m);
+	rw_rlock(lock);
+restart:
+	count = 0;
+	TAILQ_FOREACH(pv, &m->md.pv_list, pv_next) {
 		pmap = PV_PMAP(pv);
-		PMAP_LOCK(pmap);
+		if (!PMAP_TRYLOCK(pmap)) {
+			md_gen = m->md.pv_gen;
+			rw_runlock(lock);
+			PMAP_LOCK(pmap);
+			rw_rlock(lock);
+			if (md_gen != m->md.pv_gen) {
+				PMAP_UNLOCK(pmap);
+				goto restart;
+			}
+		}
 		pte = pmap_pte(pmap, pv->pv_va);
 		if ((*pte & PG_W) != 0)
 			count++;
 		PMAP_UNLOCK(pmap);
 	}
+	if ((m->flags & PG_FICTITIOUS) == 0) {
+		pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
+		TAILQ_FOREACH(pv, &pvh->pv_list, pv_next) {
+			pmap = PV_PMAP(pv);
+			if (!PMAP_TRYLOCK(pmap)) {
+				md_gen = m->md.pv_gen;
+				pvh_gen = pvh->pv_gen;
+				rw_runlock(lock);
+				PMAP_LOCK(pmap);
+				rw_rlock(lock);
+				if (md_gen != m->md.pv_gen ||
+				    pvh_gen != pvh->pv_gen) {
+					PMAP_UNLOCK(pmap);
+					goto restart;
+				}
+			}
+			pte = pmap_pde(pmap, pv->pv_va);
+			if ((*pte & PG_W) != 0)
+				count++;
+			PMAP_UNLOCK(pmap);
+		}
+	}
+	rw_runlock(lock);
+	rw_runlock(&pvh_global_lock);
 	return (count);
 }
 
@@ -4835,6 +4851,69 @@ pmap_remove_pages(pmap_t pmap)
 	pmap_free_zero_pages(&free);
 }
 
+static boolean_t
+pmap_page_test_mappings(vm_page_t m, pt_entry_t mask)
+{
+	struct rwlock *lock;
+	pv_entry_t pv;
+	struct md_page *pvh;
+	pt_entry_t *pte;
+	pmap_t pmap;
+	int md_gen, pvh_gen;
+	boolean_t rv;
+
+	rv = FALSE;
+	rw_rlock(&pvh_global_lock);
+	lock = VM_PAGE_TO_PV_LIST_LOCK(m);
+	rw_rlock(lock);
+restart:
+	TAILQ_FOREACH(pv, &m->md.pv_list, pv_next) {
+		pmap = PV_PMAP(pv);
+		if (!PMAP_TRYLOCK(pmap)) {
+			md_gen = m->md.pv_gen;
+			rw_runlock(lock);
+			PMAP_LOCK(pmap);
+			rw_rlock(lock);
+			if (md_gen != m->md.pv_gen) {
+				PMAP_UNLOCK(pmap);
+				goto restart;
+			}
+		}
+		pte = pmap_pte(pmap, pv->pv_va);
+		rv = (*pte & mask) == mask;
+		PMAP_UNLOCK(pmap);
+		if (rv)
+			goto out;
+	}
+	if ((m->flags & PG_FICTITIOUS) == 0) {
+		pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
+		TAILQ_FOREACH(pv, &pvh->pv_list, pv_next) {
+			pmap = PV_PMAP(pv);
+			if (!PMAP_TRYLOCK(pmap)) {
+				md_gen = m->md.pv_gen;
+				pvh_gen = pvh->pv_gen;
+				rw_runlock(lock);
+				PMAP_LOCK(pmap);
+				rw_rlock(lock);
+				if (md_gen != m->md.pv_gen ||
+				    pvh_gen != pvh->pv_gen) {
+					PMAP_UNLOCK(pmap);
+					goto restart;
+				}
+			}
+			pte = pmap_pde(pmap, pv->pv_va);
+			rv = (*pte & mask) == mask;
+			PMAP_UNLOCK(pmap);
+			if (rv)
+				goto out;
+		}
+	}
+out:
+	rw_runlock(lock);
+	rw_runlock(&pvh_global_lock);
+	return (rv);
+}
+
 /*
  *	pmap_is_modified:
  *
@@ -4844,7 +4923,6 @@ pmap_remove_pages(pmap_t pmap)
 boolean_t
 pmap_is_modified(vm_page_t m)
 {
-	boolean_t rv;
 
 	KASSERT((m->oflags & VPO_UNMANAGED) == 0,
 	    ("pmap_is_modified: page %p is not managed", m));
@@ -4857,39 +4935,7 @@ pmap_is_modified(vm_page_t m)
 	VM_OBJECT_ASSERT_WLOCKED(m->object);
 	if (!vm_page_xbusied(m) && (m->aflags & PGA_WRITEABLE) == 0)
 		return (FALSE);
-	rw_wlock(&pvh_global_lock);
-	rv = pmap_is_modified_pvh(&m->md) ||
-	    ((m->flags & PG_FICTITIOUS) == 0 &&
-	    pmap_is_modified_pvh(pa_to_pvh(VM_PAGE_TO_PHYS(m))));
-	rw_wunlock(&pvh_global_lock);
-	return (rv);
-}
-
-/*
- * Returns TRUE if any of the given mappings were used to modify
- * physical memory.  Otherwise, returns FALSE.  Both page and 2mpage
- * mappings are supported.
- */
-static boolean_t
-pmap_is_modified_pvh(struct md_page *pvh)
-{
-	pv_entry_t pv;
-	pt_entry_t *pte;
-	pmap_t pmap;
-	boolean_t rv;
-
-	rw_assert(&pvh_global_lock, RA_WLOCKED);
-	rv = FALSE;
-	TAILQ_FOREACH(pv, &pvh->pv_list, pv_next) {
-		pmap = PV_PMAP(pv);
-		PMAP_LOCK(pmap);
-		pte = pmap_pte(pmap, pv->pv_va);
-		rv = (*pte & (PG_M | PG_RW)) == (PG_M | PG_RW);
-		PMAP_UNLOCK(pmap);
-		if (rv)
-			break;
-	}
-	return (rv);
+	return (pmap_page_test_mappings(m, PG_M | PG_RW));
 }
 
 /*
@@ -4925,42 +4971,10 @@ pmap_is_prefaultable(pmap_t pmap, vm_off
 boolean_t
 pmap_is_referenced(vm_page_t m)
 {
-	boolean_t rv;
 
 	KASSERT((m->oflags & VPO_UNMANAGED) == 0,
 	    ("pmap_is_referenced: page %p is not managed", m));
-	rw_wlock(&pvh_global_lock);
-	rv = pmap_is_referenced_pvh(&m->md) ||
-	    ((m->flags & PG_FICTITIOUS) == 0 &&
-	    pmap_is_referenced_pvh(pa_to_pvh(VM_PAGE_TO_PHYS(m))));
-	rw_wunlock(&pvh_global_lock);
-	return (rv);
-}
-
-/*
- * Returns TRUE if any of the given mappings were referenced and FALSE
- * otherwise.  Both page and 2mpage mappings are supported.
- */
-static boolean_t
-pmap_is_referenced_pvh(struct md_page *pvh)
-{
-	pv_entry_t pv;
-	pt_entry_t *pte;
-	pmap_t pmap;
-	boolean_t rv;
-
-	rw_assert(&pvh_global_lock, RA_WLOCKED);
-	rv = FALSE;
-	TAILQ_FOREACH(pv, &pvh->pv_list, pv_next) {
-		pmap = PV_PMAP(pv);
-		PMAP_LOCK(pmap);
-		pte = pmap_pte(pmap, pv->pv_va);
-		rv = (*pte & (PG_A | PG_V)) == (PG_A | PG_V);
-		PMAP_UNLOCK(pmap);
-		if (rv)
-			break;
-	}
-	return (rv);
+	return (pmap_page_test_mappings(m, PG_A | PG_V));
 }
 
 /*

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