[PATCH 02/12] tools/xenstore: introduce accounting data array for per-domain values

[Juergen Gross <jgross@suse.com>]

Introduce the scheme of an accounting data array for per-domain
accounting data and use it initially for the number of nodes owned by
a domain.

Make the accounting data type to be unsigned int, as no data is allowed
to be negative at any time.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 tools/xenstore/xenstored_domain.c | 55 ++++++++++++++++++++-----------
 tools/xenstore/xenstored_domain.h |  5 +--
 2 files changed, 38 insertions(+), 22 deletions(-)

diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c
index 399fc920bb..9591a19189 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -69,8 +69,8 @@ struct domain
 	/* Has domain been officially introduced? */
 	bool introduced;
 
-	/* number of entry from this domain in the store */
-	int nbentry;
+	/* Accounting data for this domain. */
+	unsigned int acc[ACC_N];
 
 	/* Amount of memory allocated for this domain. */
 	int memory;
@@ -246,7 +246,7 @@ static int domain_tree_remove_sub(const void *ctx, struct connection *conn,
 
 	if (keep_orphans) {
 		set_tdb_key(node->name, &key);
-		domain->nbentry--;
+		domain_nbentry_dec(NULL, domain->domid);
 		node->perms.p[0].id = priv_domid;
 		node->acc.memory = 0;
 		domain_nbentry_inc(NULL, priv_domid);
@@ -270,7 +270,7 @@ static int domain_tree_remove_sub(const void *ctx, struct connection *conn,
 		ret = WALK_TREE_SKIP_CHILDREN;
 	}
 
-	return domain->nbentry > 0 ? ret : WALK_TREE_SUCCESS_STOP;
+	return domain->acc[ACC_NODES] ? ret : WALK_TREE_SUCCESS_STOP;
 }
 
 static void domain_tree_remove(struct domain *domain)
@@ -278,7 +278,7 @@ static void domain_tree_remove(struct domain *domain)
 	int ret;
 	struct walk_funcs walkfuncs = { .enter = domain_tree_remove_sub };
 
-	if (domain->nbentry > 0) {
+	if (domain->acc[ACC_NODES]) {
 		ret = walk_node_tree(domain, NULL, "/", &walkfuncs, domain);
 		if (ret == WALK_TREE_ERROR_STOP)
 			syslog(LOG_ERR,
@@ -441,7 +441,7 @@ int domain_get_quota(const void *ctx, struct connection *conn,
 	resp = talloc_asprintf_append(resp, "%-16s: %8d\n", #t, e); \
 	if (!resp) return ENOMEM
 
-	ent(nodes, d->nbentry);
+	ent(nodes, d->acc[ACC_NODES]);
 	ent(watches, d->nbwatch);
 	ent(transactions, ta);
 	ent(outstanding, d->nboutstanding);
@@ -1050,8 +1050,21 @@ int domain_adjust_node_perms(struct node *node)
 	return 0;
 }
 
-static int domain_nbentry_add(struct connection *conn, unsigned int domid,
-			      int add, bool dom_exists)
+static int domain_acc_add_chk(struct domain *d, unsigned int what, int add,
+			      unsigned int domid)
+{
+	if ((add < 0 && -add > d->acc[what]) ||
+	    (d->acc[what] + add) > INT_MAX) {
+		syslog(LOG_ERR, "Accounting error: domain %u type %u val %u\n",
+		       domid, what, d->acc[what] + add);
+		return (add < 0) ? 0 : INT_MAX;
+	}
+
+	return d->acc[what] + add;
+}
+
+static int domain_acc_add(struct connection *conn, unsigned int domid,
+			  unsigned int what, int add, bool dom_exists)
 {
 	struct domain *d;
 	struct list_head *head;
@@ -1074,47 +1087,49 @@ static int domain_nbentry_add(struct connection *conn, unsigned int domid,
 		}
 	}
 
-	if (conn && conn->transaction) {
+	if (conn && conn->transaction && what < ACC_TR_N) {
 		head = transaction_get_changed_domains(conn->transaction);
-		ret = acc_add_changed_dom(conn->transaction, head, ACC_NODES,
+		ret = acc_add_changed_dom(conn->transaction, head, what,
 					  add, domid);
 		if (errno) {
 			fail_transaction(conn->transaction);
 			return -1;
 		}
-		return d->nbentry + ret;
+		return domain_acc_add_chk(d, what, ret, domid);
 	}
 
-	d->nbentry += add;
+	d->acc[what] = domain_acc_add_chk(d, what, add, domid);
 
-	return d->nbentry;
+	return d->acc[what];
 }
 
 int domain_nbentry_inc(struct connection *conn, unsigned int domid)
 {
-	return (domain_nbentry_add(conn, domid, 1, false) < 0) ? errno : 0;
+	return (domain_acc_add(conn, domid, ACC_NODES, 1, false) < 0)
+	       ? errno : 0;
 }
 
 int domain_nbentry_dec(struct connection *conn, unsigned int domid)
 {
-	return (domain_nbentry_add(conn, domid, -1, true) < 0) ? errno : 0;
+	return (domain_acc_add(conn, domid, ACC_NODES, -1, true) < 0)
+	       ? errno : 0;
 }
 
 int domain_nbentry_fix(unsigned int domid, int num, bool update)
 {
 	int ret;
 
-	ret = domain_nbentry_add(NULL, domid, update ? num : 0, update);
+	ret = domain_acc_add(NULL, domid, ACC_NODES, update ? num : 0, update);
 	if (ret < 0 || update)
 		return ret;
 
 	return domid_is_unprivileged(domid) ? ret + num : 0;
 }
 
-int domain_nbentry(struct connection *conn)
+unsigned int domain_nbentry(struct connection *conn)
 {
 	return domain_is_unprivileged(conn)
-	       ? domain_nbentry_add(conn, conn->id, 0, true) : 0;
+	       ? domain_acc_add(conn, conn->id, ACC_NODES, 0, true) : 0;
 }
 
 static bool domain_chk_quota(struct domain *domain, int mem)
@@ -1591,7 +1606,7 @@ static int domain_check_acc_init_sub(void *k, void *v, void *arg)
 	 * If everything is correct incrementing the value for each node will
 	 * result in dom->nodes being 0 at the end.
 	 */
-	dom->nodes = -d->nbentry;
+	dom->nodes = -d->acc[ACC_NODES];
 
 	if (!hashtable_insert(domains, &dom->domid, dom)) {
 		talloc_free(dom);
@@ -1646,7 +1661,7 @@ static int domain_check_acc_sub(void *k, void *v, void *arg)
 	if (!d)
 		return 0;
 
-	d->nbentry += dom->nodes;
+	d->acc[ACC_NODES] += dom->nodes;
 
 	return 0;
 }
diff --git a/tools/xenstore/xenstored_domain.h b/tools/xenstore/xenstored_domain.h
index 124b9e1b1e..d2563d33e7 100644
--- a/tools/xenstore/xenstored_domain.h
+++ b/tools/xenstore/xenstored_domain.h
@@ -21,7 +21,8 @@
 
 enum {
 	ACC_NODES,
-	ACC_TR_N	/* Number of elements per transaction and domain. */
+	ACC_TR_N,        /* Number of elements per transaction and domain. */
+	ACC_N = ACC_TR_N /* Number of elements per domain. */
 };
 
 void handle_event(void);
@@ -72,7 +73,7 @@ int domain_alloc_permrefs(struct node_perms *perms);
 int domain_nbentry_inc(struct connection *conn, unsigned int domid);
 int domain_nbentry_dec(struct connection *conn, unsigned int domid);
 int domain_nbentry_fix(unsigned int domid, int num, bool update);
-int domain_nbentry(struct connection *conn);
+unsigned int domain_nbentry(struct connection *conn);
 int domain_memory_add(unsigned int domid, int mem, bool no_quota_check);
 
 /*
-- 
2.35.3