From: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Date: Wed, 11 Jan 2012 20:29:55 +0000 (-0200)
Subject: modprobe: break dependency loop by checking if module is loaded
X-Git-Tag: v4~49
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=af0ff2f22ac189ce9f51b597711aee5c178b0378;p=thirdparty%2Fkmod.git

modprobe: break dependency loop by checking if module is loaded

modprobe doesn't have support for handling dependency loop. That happens
with poorly written softdeps that can introduce a loop. We must deal
with them like it's being done in libkmod.

However, we can break a dependency loop when the dependency was already
inserted. This commit fixes this issue, that happens in the following
scenario:

dependencies:
-------------

modA:
modB: modA
modC: modA

config:

softdep modA post: modB modC

This creates the following loop:

modA
    inserted ok
    handle post-soft-deps of modA -> modB modC
        modB
            handle dependencies of modB -> modA
                modA is already inserted
                    handle post-soft-deps of modA -> modB modC

And so on and so forth.

Now we break the loop by checking if module is already inserted, before
handling it. Thus this gives us:

modA
    inserted ok
    handle post-soft-deps of modA -> modB modC
        modB
            handle dependencies of modB -> modA
                modA is already inserted
            inserted ok
        modC
            handle dependencies of modC -> modA
                modA is already inserted
            inserted ok
---

diff --git a/tools/kmod-modprobe.c b/tools/kmod-modprobe.c
index 35224bbf..6ed605c8 100644
--- a/tools/kmod-modprobe.c
+++ b/tools/kmod-modprobe.c
@@ -620,6 +620,14 @@ static int insmod_do_deps_list(struct kmod_module *parent,
 		const char *cmd, *opts, *dmname = kmod_module_get_name(dm);
 		int r;
 
+		if (!ignore_loaded) {
+			int state = kmod_module_get_initstate(dm);
+			if (state == KMOD_MODULE_LIVE ||
+					state == KMOD_MODULE_COMING ||
+					state == KMOD_MODULE_BUILTIN)
+				continue;
+		}
+
 		r = insmod_do_dependencies(dm);
 		if (r < 0) {
 			WRN("could not insert dependencies of '%s': %s\n",
@@ -641,14 +649,6 @@ static int insmod_do_deps_list(struct kmod_module *parent,
 			goto dep_error;
 		}
 
-		if (!ignore_loaded) {
-			int state = kmod_module_get_initstate(dm);
-			if (state == KMOD_MODULE_LIVE ||
-					state == KMOD_MODULE_COMING ||
-					state == KMOD_MODULE_BUILTIN)
-				goto dep_done;
-		}
-
 		cmd = kmod_module_get_install_commands(dm);
 		if (cmd) {
 			r = command_do(dm, "install", cmd, NULL);