modprobe broken with recursive deps

[Mike Frysinger]

off hand, the last known working version is busybox 1.4.1.  i imagine it 
worked with later versions, but that is the last one that is readily 
accessible under my cross-compile setup that i can confirm.  all of 1.13.x+ 
seem to be broken.

it's a simple config: start with allnoconfig, then just enable insmod, rmmod, 
lsmod, and modprobe (linux-2.6 only).

then with a simple dependency list:
.../snd-page-alloc.ko:
.../snd.ko: .../soundcore.ko
.../snd-timer.ko: .../snd.ko
.../soundcore.ko:
.../snd-pcm.ko: .../snd-timer.ko .../snd-page-alloc.ko .../snd.ko

doing `modprobe` on any module that only has a dependency list <=1 level deep 
works fine.  as soon as i try to modprobe anything deeper, modprobe fails to 
act recursively.  so lets look at the case of `modprobe snd-pcm` ...

reading (and testing) the code shows:
 - modprobe_main() adds only specified modules ("snd-pcm" here) to the global 
modentry db
 - load_modules_dep() only loads dependencies only for modules already in the 
modentry db
	- snd-pcm's dependencies get recorded properly (snd-timer/snd-page-alloc/snd)
	- no other module or its dependencies are known (so the fact that snd 
requires soundcore is lost/ignored)
 - modprobe_main() walks the requested module list and calls do_modprobe() on 
each one in it (only "snd-pcm" here)
 - do_modprobe() attempts to load only modules specified in the modules direct 
dependencies (snd-timer/snd-page-alloc/snd)
	- init_module() fails on "snd" due to unknown symbols because "soundcore" was 
never requested let alone loaded

seems a lot of the cleanup work that was added stuck to the list concept at 
the expense of unlimited recursion depth ...

i'm not familiar enough to commit a fix here, but what i had to do to make it 
work is:
 - have load_modules_dep() load all dependency info
 - have do_modprobe() recursively call do_modprobe() on each dependency

@@ -222,2 +227,3 @@ static int do_modprobe(struct module_entry *m)
        m2 = get_or_add_modentry(fn);
+       rc = do_modprobe(m2);
        if (option_mask32 & MODPROBE_OPT_REMOVE) {
@@ -268,5 +274,3 @@ static void load_modules_dep(void)

-   while (G.num_unresolved_deps
-    && config_read(p, tokens, 2, 1, "# \t", PARSE_NORMAL)
-   ) {
+   while (config_read(p, tokens, 2, 1, "# \t", PARSE_NORMAL)) {
        colon = last_char_is(tokens[0], ':');
@@ -276,3 +280,3 @@ static void load_modules_dep(void)

-       m = get_modentry(tokens[0]);
+       m = get_or_add_modentry(tokens[0]);
        if (m == NULL)
@@ -289,4 +295,5 @@ static void load_modules_dep(void)
        m->flags |= MODULE_FLAG_FOUND_IN_MODDEP;
-       if ((m->flags & MODULE_FLAG_NEED_DEPS) && (m->deps == NULL)) {
-           G.num_unresolved_deps--;
+       if ((m->deps == NULL)) {
+           if (m->flags & MODULE_FLAG_NEED_DEPS)
+               G.num_unresolved_deps--;
            llist_add_to(&m->deps, xstrdup(tokens[0]));
-mike
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