cgroup: small cleanups and coding style fixes

A number of simplications and adjustments to brings things closer to our
coding style.

src/basic/cgroup-util.c

@@ -29,7 +29,6 @@
 #include <sys/types.h>
 #include <ftw.h>
 
-#include "cgroup-util.h"
 #include "set.h"
 #include "macro.h"
 #include "util.h"
@@ -41,6 +40,7 @@
 #include "special.h"
 #include "mkdir.h"
 #include "login-util.h"
+#include "cgroup-util.h"
 
 int cg_enumerate_processes(const char *controller, const char *path, FILE **_f) {
         _cleanup_free_ char *fs = NULL;
@@ -197,7 +197,7 @@ int cg_kill(const char *controller, const char *path, int sig, bool sigcont, boo
                                         ret = -errno;
                         } else {
                                 if (sigcont && sig != SIGKILL)
-                                        kill(pid, SIGCONT);
+                                        (void) kill(pid, SIGCONT);
 
                                 if (ret == 0)
                                         ret = 1;
@@ -233,7 +233,7 @@ int cg_kill(const char *controller, const char *path, int sig, bool sigcont, boo
 int cg_kill_recursive(const char *controller, const char *path, int sig, bool sigcont, bool ignore_self, bool rem, Set *s) {
         _cleanup_set_free_ Set *allocated_set = NULL;
         _cleanup_closedir_ DIR *d = NULL;
-        int r, ret = 0;
+        int r, ret;
         char *fn;
 
         assert(path);
@@ -264,7 +264,7 @@ int cg_kill_recursive(const char *controller, const char *path, int sig, bool si
                         return -ENOMEM;
 
                 r = cg_kill_recursive(controller, p, sig, sigcont, ignore_self, rem, s);
-                if (ret >= 0 && r != 0)
+                if (r != 0 && ret >= 0)
                         ret = r;
         }
 
@@ -390,12 +390,8 @@ int cg_migrate_recursive(
 
                 p = strjoin(pfrom, "/", fn, NULL);
                 free(fn);
-                if (!p) {
+                if (!p)
-                        if (ret >= 0)
+                        return -ENOMEM;
-                                return -ENOMEM;
-
-                        return ret;
-                }
 
                 r = cg_migrate_recursive(cfrom, p, cto, pto, ignore_self, rem);
                 if (r != 0 && ret >= 0)
@@ -436,13 +432,15 @@ int cg_migrate_recursive_fallback(
                 /* This didn't work? Then let's try all prefixes of the destination */
 
                 PATH_FOREACH_PREFIX(prefix, pto) {
-                        r = cg_migrate_recursive(cfrom, pfrom, cto, prefix, ignore_self, rem);
+                        int q;
-                        if (r >= 0)
+
-                                break;
+                        q = cg_migrate_recursive(cfrom, pfrom, cto, prefix, ignore_self, rem);
+                        if (q >= 0)
+                                return q;
                 }
         }
 
-        return 0;
+        return r;
 }
 
 static const char *normalize_controller(const char *controller) {
@@ -557,7 +555,7 @@ static int trim_cb(const char *path, const struct stat *sb, int typeflag, struct
         if (ftwbuf->level < 1)
                 return 0;
 
-        rmdir(path);
+        (void) rmdir(path);
         return 0;
 }
 
@@ -572,8 +570,14 @@ int cg_trim(const char *controller, const char *path, bool delete_root) {
                 return r;
 
         errno = 0;
-        if (nftw(fs, trim_cb, 64, FTW_DEPTH|FTW_MOUNT|FTW_PHYS) != 0)
+        if (nftw(fs, trim_cb, 64, FTW_DEPTH|FTW_MOUNT|FTW_PHYS) != 0) {
-                r = errno ? -errno : -EIO;
+                if (errno == ENOENT)
+                        r = 0;
+                else if (errno != 0)
+                        r = -errno;
+                else
+                        r = -EIO;
+        }
 
         if (delete_root) {
                 if (rmdir(fs) < 0 && errno != ENOENT)
@@ -672,13 +676,15 @@ int cg_attach_fallback(const char *controller, const char *path, pid_t pid) {
                  * the destination */
 
                 PATH_FOREACH_PREFIX(prefix, path) {
-                        r = cg_attach(controller, prefix, pid);
+                        int q;
-                        if (r >= 0)
+
-                                break;
+                        q = cg_attach(controller, prefix, pid);
+                        if (q >= 0)
+                                return q;
                 }
         }
 
-        return 0;
+        return r;
 }
 
 int cg_set_group_access(
@@ -691,7 +697,8 @@ int cg_set_group_access(
         _cleanup_free_ char *fs = NULL;
         int r;
 
-        assert(path);
+        if (mode == MODE_INVALID && uid == UID_INVALID && gid == GID_INVALID)
+                return 0;
 
         if (mode != MODE_INVALID)
                 mode &= 0777;
@@ -827,7 +834,7 @@ int cg_install_release_agent(const char *controller, const char *agent) {
                 return r;
 
         sc = strstrip(contents);
-        if (sc[0] == 0) {
+        if (isempty(sc)) {
                 r = write_string_file(fs, agent, 0);
                 if (r < 0)
                         return r;
@@ -1877,6 +1884,11 @@ int cg_kernel_controllers(Set *controllers) {
 
         assert(controllers);
 
+        /* Determines the full list of kernel-known controllers. Might
+         * include controllers we don't actually support, arbitrary
+         * named hierarchies and controllers that aren't currently
+         * accessible (because not mounted). */
+
         f = fopen("/proc/cgroups", "re");
         if (!f) {
                 if (errno == ENOENT)
@@ -1897,7 +1909,7 @@ int cg_kernel_controllers(Set *controllers) {
                         if (feof(f))
                                 break;
 
-                        if (ferror(f) && errno)
+                        if (ferror(f) && errno != 0)
                                 return -errno;
 
                         return -EBADMSG;

src/core/main.c

@@ -2043,7 +2043,7 @@ finish:
                  * kernel; at this point, we will not listen to the
                  * signals anyway */
                 if (detect_container(NULL) <= 0)
-                        cg_uninstall_release_agent(SYSTEMD_CGROUP_CONTROLLER);
+                        (void) cg_uninstall_release_agent(SYSTEMD_CGROUP_CONTROLLER);
 
                 execve(SYSTEMD_SHUTDOWN_BINARY_PATH, (char **) command_line, env_block);
                 log_error_errno(errno, "Failed to execute shutdown binary, %s: %m",