list: introduce LIST_FOREACH_BACKWARDS() macro and drop LIST_FOREACH_AFTER/BEFORE()

src/basic/list.h

@@ -142,11 +142,8 @@
 #define LIST_FOREACH_SAFE(name,i,n,head)                                \
         for ((i) = (head); (i) && (((n) = (i)->name##_next), 1); (i) = (n))
 
-#define LIST_FOREACH_BEFORE(name,i,p)                                   \
-        for ((i) = (p)->name##_prev; (i); (i) = (i)->name##_prev)
-
-#define LIST_FOREACH_AFTER(name,i,p)                                    \
-        for ((i) = (p)->name##_next; (i); (i) = (i)->name##_next)
+#define LIST_FOREACH_BACKWARDS(name,i,p)                                \
+        for ((i) = (p); (i); (i) = (i)->name##_prev)
 
 /* Iterate through all the members of the list p is included in, but skip over p */
 #define LIST_FOREACH_OTHERS(name,i,p)                                   \

src/core/device.c

@@ -771,11 +771,11 @@ static Unit *device_following(Unit *u) {
                 return NULL;
 
         /* Make everybody follow the unit that's named after the sysfs path */
-        LIST_FOREACH_AFTER(same_sysfs, other, d)
+        LIST_FOREACH(same_sysfs, other, d->same_sysfs_next)
                 if (startswith(UNIT(other)->id, "sys-"))
                         return UNIT(other);
 
-        LIST_FOREACH_BEFORE(same_sysfs, other, d) {
+        LIST_FOREACH_BACKWARDS(same_sysfs, other, d->same_sysfs_prev) {
                 if (startswith(UNIT(other)->id, "sys-"))
                         return UNIT(other);
 
@@ -802,13 +802,13 @@ static int device_following_set(Unit *u, Set **_set) {
         if (!set)
                 return -ENOMEM;
 
-        LIST_FOREACH_AFTER(same_sysfs, other, d) {
+        LIST_FOREACH(same_sysfs, other, d->same_sysfs_next) {
                 r = set_put(set, other);
                 if (r < 0)
                         return r;
         }
 
-        LIST_FOREACH_BEFORE(same_sysfs, other, d) {
+        LIST_FOREACH_BACKWARDS(same_sysfs, other, d->same_sysfs_prev) {
                 r = set_put(set, other);
                 if (r < 0)
                         return r;

src/core/swap.c

@@ -1323,11 +1323,11 @@ static Unit *swap_following(Unit *u) {
         if (streq_ptr(s->what, s->devnode))
                 return NULL;
 
-        LIST_FOREACH_AFTER(same_devnode, other, s)
+        LIST_FOREACH(same_devnode, other, s->same_devnode_next)
                 if (streq_ptr(other->what, other->devnode))
                         return UNIT(other);
 
-        LIST_FOREACH_BEFORE(same_devnode, other, s) {
+        LIST_FOREACH_BACKWARDS(same_devnode, other, s->same_devnode_prev) {
                 if (streq_ptr(other->what, other->devnode))
                         return UNIT(other);
 

src/udev/udev-rules.c

@@ -1154,7 +1154,7 @@ static void rule_resolve_goto(UdevRuleFile *rule_file) {
                 if (!FLAGS_SET(line->type, LINE_HAS_GOTO))
                         continue;
 
-                LIST_FOREACH_AFTER(rule_lines, i, line)
+                LIST_FOREACH(rule_lines, i, line->rule_lines_next)
                         if (streq_ptr(i->label, line->goto_label)) {
                                 line->goto_line = i;
                                 break;