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Date:      Sun, 8 Sep 2019 20:28:07 +0000 (UTC)
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org
Subject:   svn commit: r352038 - stable/12/sys/kern
Message-ID:  <201909082028.x88KS7Gv028279@repo.freebsd.org>
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Author: markj
Date: Sun Sep  8 20:28:06 2019
New Revision: 352038
URL: https://svnweb.freebsd.org/changeset/base/352038

Log:
  MFC r351547, r351549:
  Fix several logic issues in domainset_empty_vm().

Modified:
  stable/12/sys/kern/kern_cpuset.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/kern/kern_cpuset.c
==============================================================================
--- stable/12/sys/kern/kern_cpuset.c	Sun Sep  8 19:54:28 2019	(r352037)
+++ stable/12/sys/kern/kern_cpuset.c	Sun Sep  8 20:28:06 2019	(r352038)
@@ -457,7 +457,7 @@ static struct domainset *
 _domainset_create(struct domainset *domain, struct domainlist *freelist)
 {
 	struct domainset *ndomain;
-	int i, j, max;
+	int i, j;
 
 	KASSERT(domain->ds_cnt <= vm_ndomains,
 	    ("invalid domain count in domainset %p", domain));
@@ -476,8 +476,7 @@ _domainset_create(struct domainset *domain, struct dom
 	if (ndomain == NULL) {
 		LIST_INSERT_HEAD(&cpuset_domains, domain, ds_link);
 		domain->ds_cnt = DOMAINSET_COUNT(&domain->ds_mask);
-		max = DOMAINSET_FLS(&domain->ds_mask) + 1;
-		for (i = 0, j = 0; i < max; i++)
+		for (i = 0, j = 0; i < DOMAINSET_FLS(&domain->ds_mask); i++)
 			if (DOMAINSET_ISSET(i, &domain->ds_mask))
 				domain->ds_order[j++] = i;
 	}
@@ -500,25 +499,31 @@ _domainset_create(struct domainset *domain, struct dom
 static bool
 domainset_empty_vm(struct domainset *domain)
 {
-	int i, j, max;
+	domainset_t empty;
+	int i, j;
 
-	max = DOMAINSET_FLS(&domain->ds_mask) + 1;
-	for (i = 0; i < max; i++)
-		if (DOMAINSET_ISSET(i, &domain->ds_mask) && VM_DOMAIN_EMPTY(i))
-			DOMAINSET_CLR(i, &domain->ds_mask);
+	DOMAINSET_ZERO(&empty);
+	for (i = 0; i < vm_ndomains; i++)
+		if (VM_DOMAIN_EMPTY(i))
+			DOMAINSET_SET(i, &empty);
+	if (DOMAINSET_SUBSET(&empty, &domain->ds_mask))
+		return (true);
+
+	/* Remove empty domains from the set and recompute. */
+	DOMAINSET_NAND(&domain->ds_mask, &empty);
 	domain->ds_cnt = DOMAINSET_COUNT(&domain->ds_mask);
-	max = DOMAINSET_FLS(&domain->ds_mask) + 1;
-	for (i = j = 0; i < max; i++) {
+	for (i = j = 0; i < DOMAINSET_FLS(&domain->ds_mask); i++)
 		if (DOMAINSET_ISSET(i, &domain->ds_mask))
 			domain->ds_order[j++] = i;
-		else if (domain->ds_policy == DOMAINSET_POLICY_PREFER &&
-		    domain->ds_prefer == i && domain->ds_cnt > 1) {
-			domain->ds_policy = DOMAINSET_POLICY_ROUNDROBIN;
-			domain->ds_prefer = -1;
-		}
+
+	/* Convert a PREFER policy referencing an empty domain to RR. */
+	if (domain->ds_policy == DOMAINSET_POLICY_PREFER &&
+	    DOMAINSET_ISSET(domain->ds_prefer, &empty)) {
+		domain->ds_policy = DOMAINSET_POLICY_ROUNDROBIN;
+		domain->ds_prefer = -1;
 	}
 
-	return (DOMAINSET_EMPTY(&domain->ds_mask));
+	return (false);
 }
 
 /*

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