1 files changed, 15 insertions, 11 deletions

diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index 8d0912c1d01a..cec6189126ba 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -115,16 +115,20 @@ static struct unix_vertex *unix_edge_successor(struct unix_edge *edge)
 static LIST_HEAD(unix_unvisited_vertices);
 
 enum unix_vertex_index {
-	UNIX_VERTEX_INDEX_UNVISITED,
+	UNIX_VERTEX_INDEX_MARK1,
+	UNIX_VERTEX_INDEX_MARK2,
 	UNIX_VERTEX_INDEX_START,
 };
 
+static unsigned long unix_vertex_unvisited_index = UNIX_VERTEX_INDEX_MARK1;
+
 static void unix_add_edge(struct scm_fp_list *fpl, struct unix_edge *edge)
 {
 	struct unix_vertex *vertex = edge->predecessor->vertex;
 
 	if (!vertex) {
 		vertex = list_first_entry(&fpl->vertices, typeof(*vertex), entry);
+		vertex->index = unix_vertex_unvisited_index;
 		vertex->out_degree = 0;
 		INIT_LIST_HEAD(&vertex->edges);
 
@@ -265,6 +269,7 @@ void unix_destroy_fpl(struct scm_fp_list *fpl)
 }
 
 static LIST_HEAD(unix_visited_vertices);
+static unsigned long unix_vertex_grouped_index = UNIX_VERTEX_INDEX_MARK2;
 
 static void __unix_walk_scc(struct unix_vertex *vertex)
 {
@@ -274,10 +279,10 @@ static void __unix_walk_scc(struct unix_vertex *vertex)
 	LIST_HEAD(edge_stack);
 
 next_vertex:
-	/* Push vertex to vertex_stack.
+	/* Push vertex to vertex_stack and mark it as on-stack
+	 * (index >= UNIX_VERTEX_INDEX_START).
 	 * The vertex will be popped when finalising SCC later.
 	 */
-	vertex->on_stack = true;
 	list_add(&vertex->scc_entry, &vertex_stack);
 
 	vertex->index = index;
@@ -291,7 +296,7 @@ next_vertex:
 		if (!next_vertex)
 			continue;
 
-		if (next_vertex->index == UNIX_VERTEX_INDEX_UNVISITED) {
+		if (next_vertex->index == unix_vertex_unvisited_index) {
 			/* Iterative deepening depth first search
 			 *
 			 *   1. Push a forward edge to edge_stack and set
@@ -317,7 +322,7 @@ prev_vertex:
 			 * to skip SCC finalisation.
 			 */
 			vertex->lowlink = min(vertex->lowlink, next_vertex->lowlink);
-		} else if (next_vertex->on_stack) {
+		} else if (next_vertex->index != unix_vertex_grouped_index) {
 			/* Loop detected by a back/cross edge.
 			 *
 			 * The successor is on vertex_stack, so two vertices are
@@ -344,7 +349,8 @@ prev_vertex:
 			/* Don't restart DFS from this vertex in unix_walk_scc(). */
 			list_move_tail(&vertex->entry, &unix_visited_vertices);
 
-			vertex->on_stack = false;
+			/* Mark vertex as off-stack. */
+			vertex->index = unix_vertex_grouped_index;
 		}
 
 		list_del(&scc);
@@ -357,20 +363,18 @@ prev_vertex:
 
 static void unix_walk_scc(void)
 {
-	struct unix_vertex *vertex;
-
-	list_for_each_entry(vertex, &unix_unvisited_vertices, entry)
-		vertex->index = UNIX_VERTEX_INDEX_UNVISITED;
-
 	/* Visit every vertex exactly once.
 	 * __unix_walk_scc() moves visited vertices to unix_visited_vertices.
 	 */
 	while (!list_empty(&unix_unvisited_vertices)) {
+		struct unix_vertex *vertex;
+
 		vertex = list_first_entry(&unix_unvisited_vertices, typeof(*vertex), entry);
 		__unix_walk_scc(vertex);
 	}
 
 	list_replace_init(&unix_visited_vertices, &unix_unvisited_vertices);
+	swap(unix_vertex_unvisited_index, unix_vertex_grouped_index);
 }
 
 static LIST_HEAD(gc_candidates);