core: normalize 'r' variable handling in unit_attach_pids_to_cgroup() a bit

The 'r' variable is our "go-to" variable for error return codes, all
across our codebase. In unit_attach_pids_to_cgroup() it was so far used
in a strange way for most of the function: instead of directly storing
the error codes of functions we call we'd store it in a local variable
'q' instead, and propagate it to 'r' only  in some cases finally we'd
return the ultimate result of 'r'.

Let's normalize this a bit: let's always store error return values in
'r', and then use 'ret' as the variable to sometimes propagate errors
to, and then return that.

This also allows us to get rid of one local variable.

No actual codeflow changes, just some renaming of variables that allows
us to remove one.

(cherry picked from commit db4229d12f48663400802171b336c7cadbbe04ef)

1 files changed, 19 insertions, 19 deletions

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index 5c07aa71d1..1551d57e90 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -2137,7 +2137,7 @@ int unit_attach_pids_to_cgroup(Unit *u, Set *pids, const char *suffix_path) {
         CGroupMask delegated_mask;
         const char *p;
         void *pidp;
-        int r, q;
+        int ret, r;
 
         assert(u);
 
@@ -2164,16 +2164,16 @@ int unit_attach_pids_to_cgroup(Unit *u, Set *pids, const char *suffix_path) {
 
         delegated_mask = unit_get_delegate_mask(u);
 
-        r = 0;
+        ret = 0;
         SET_FOREACH(pidp, pids) {
                 pid_t pid = PTR_TO_PID(pidp);
 
                 /* First, attach the PID to the main cgroup hierarchy */
-                q = cg_attach(SYSTEMD_CGROUP_CONTROLLER, p, pid);
-                if (q < 0) {
-                        bool again = MANAGER_IS_USER(u->manager) && ERRNO_IS_PRIVILEGE(q);
+                r = cg_attach(SYSTEMD_CGROUP_CONTROLLER, p, pid);
+                if (r < 0) {
+                        bool again = MANAGER_IS_USER(u->manager) && ERRNO_IS_PRIVILEGE(r);
 
-                        log_unit_full_errno(u, again ? LOG_DEBUG : LOG_INFO,  q,
+                        log_unit_full_errno(u, again ? LOG_DEBUG : LOG_INFO,  r,
                                             "Couldn't move process "PID_FMT" to%s requested cgroup '%s': %m",
                                             pid, again ? " directly" : "", empty_to_root(p));
 
@@ -2192,16 +2192,16 @@ int unit_attach_pids_to_cgroup(Unit *u, Set *pids, const char *suffix_path) {
                                         continue; /* When the bus thing worked via the bus we are fully done for this PID. */
                         }
 
-                        if (r >= 0)
-                                r = q; /* Remember first error */
+                        if (ret >= 0)
+                                ret = r; /* Remember first error */
 
                         continue;
                 }
 
-                q = cg_all_unified();
-                if (q < 0)
-                        return q;
-                if (q > 0)
+                r = cg_all_unified();
+                if (r < 0)
+                        return r;
+                if (r > 0)
                         continue;
 
                 /* In the legacy hierarchy, attach the process to the request cgroup if possible, and if not to the
@@ -2216,11 +2216,11 @@ int unit_attach_pids_to_cgroup(Unit *u, Set *pids, const char *suffix_path) {
 
                         /* If this controller is delegated and realized, honour the caller's request for the cgroup suffix. */
                         if (delegated_mask & u->cgroup_realized_mask & bit) {
-                                q = cg_attach(cgroup_controller_to_string(c), p, pid);
-                                if (q >= 0)
+                                r = cg_attach(cgroup_controller_to_string(c), p, pid);
+                                if (r >= 0)
                                         continue; /* Success! */
 
-                                log_unit_debug_errno(u, q, "Failed to attach PID " PID_FMT " to requested cgroup %s in controller %s, falling back to unit's cgroup: %m",
+                                log_unit_debug_errno(u, r, "Failed to attach PID " PID_FMT " to requested cgroup %s in controller %s, falling back to unit's cgroup: %m",
                                                      pid, empty_to_root(p), cgroup_controller_to_string(c));
                         }
 
@@ -2231,14 +2231,14 @@ int unit_attach_pids_to_cgroup(Unit *u, Set *pids, const char *suffix_path) {
                         if (!realized)
                                 continue; /* Not even realized in the root slice? Then let's not bother */
 
-                        q = cg_attach(cgroup_controller_to_string(c), realized, pid);
-                        if (q < 0)
-                                log_unit_debug_errno(u, q, "Failed to attach PID " PID_FMT " to realized cgroup %s in controller %s, ignoring: %m",
+                        r = cg_attach(cgroup_controller_to_string(c), realized, pid);
+                        if (r < 0)
+                                log_unit_debug_errno(u, r, "Failed to attach PID " PID_FMT " to realized cgroup %s in controller %s, ignoring: %m",
                                                      pid, realized, cgroup_controller_to_string(c));
                 }
         }
 
-        return r;
+        return ret;
 }
 
 static bool unit_has_mask_realized(