From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Sun, 13 Feb 2022 11:52:53 +0000 (+0900)
Subject: core/execute: warn when threaded mode is detected
X-Git-Tag: v251-rc1~276^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=702cf08fceaa7df8476e56e3648b211e58700bc0;p=thirdparty%2Fsystemd.git

core/execute: warn when threaded mode is detected

Prompted by #22486.
---

diff --git a/src/core/execute.c b/src/core/execute.c
index 380755eb09b..72f3534908a 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -4250,6 +4250,12 @@ static int exec_child(
                 }
 
                 r = cg_attach_everywhere(params->cgroup_supported, p, 0, NULL, NULL);
+                if (r == -EUCLEAN) {
+                        *exit_status = EXIT_CGROUP;
+                        return log_unit_error_errno(unit, r, "Failed to attach process to cgroup %s "
+                                                    "because the cgroup or one of its parents or "
+                                                    "siblings is in the threaded mode: %m", p);
+                }
                 if (r < 0) {
                         *exit_status = EXIT_CGROUP;
                         return log_unit_error_errno(unit, r, "Failed to attach to cgroup %s: %m", p);
diff --git a/src/shared/cgroup-setup.c b/src/shared/cgroup-setup.c
index 8bda66ca36a..38a6755d178 100644
--- a/src/shared/cgroup-setup.c
+++ b/src/shared/cgroup-setup.c
@@ -346,6 +346,9 @@ int cg_attach(const char *controller, const char *path, pid_t pid) {
         xsprintf(c, PID_FMT "\n", pid);
 
         r = write_string_file(fs, c, WRITE_STRING_FILE_DISABLE_BUFFER);
+        if (r == -EOPNOTSUPP && cg_is_threaded(controller, path) > 0)
+                /* When the threaded mode is used, we cannot read/write the file. Let's return recognizable error. */
+                return -EUCLEAN;
         if (r < 0)
                 return r;