cgroup: Remove data-race around cgrp_dfl_visible

There's a seemingly harmless data-race around cgrp_dfl_visible detected by kernel concurrency sanitizer. Let's remove it by throwing WRITE/READ_ONCE at it. Signed-off-by: Tejun Heo <[email protected]> Reported-by: Abhishek Shah <[email protected]> Cc: Gabriel Ryan <[email protected]> Reviewed-by: Christian Brauner (Microsoft) <[email protected]> Link: https://lore.kernel.org/netdev/20220819072256.fn7ctciefy4fc4cu@wittgenstein/
majek · Sep 4, 2022 · dc79ec1 · dc79ec1
1 parent c0f2df4
commit dc79ec1
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
@@ -2173,7 +2173,7 @@ static int cgroup_get_tree(struct fs_context *fc)
 	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
 	int ret;
 
-	cgrp_dfl_visible = true;
+	WRITE_ONCE(cgrp_dfl_visible, true);
 	cgroup_get_live(&cgrp_dfl_root.cgrp);
 	ctx->root = &cgrp_dfl_root;
 
@@ -6098,7 +6098,7 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
 		struct cgroup *cgrp;
 		int ssid, count = 0;
 
-		if (root == &cgrp_dfl_root && !cgrp_dfl_visible)
+		if (root == &cgrp_dfl_root && !READ_ONCE(cgrp_dfl_visible))
 			continue;
 
 		seq_printf(m, "%d:", root->hierarchy_id);