modprobe: abort on dependency loop that cannot be broken

diff --git a/TODO b/TODO
index 096202b..027bb4b 100644 (file)
--- a/TODO
+++ b/TODO
@@ -18,7 +18,6 @@ Features:
 
 * provide 1:1 compatibility with module-init-tools's modprobe
    - dump configuration
-   - deal with dependency loop
 
 * Add manpages: copy them from module-init-tools and make the necessary changes
 

diff --git a/tools/kmod-modprobe.c b/tools/kmod-modprobe.c
index 33510f0..29b7088 100644 (file)
--- a/tools/kmod-modprobe.c
+++ b/tools/kmod-modprobe.c
@@ -1,5 +1,5 @@
 /*
- * kmod-modprob - manage linux kernel modules using libkmod.
+ * kmod-modprobe - manage linux kernel modules using libkmod.
  *
  * Copyright (C) 2011-2012  ProFUSION embedded systems
  *
@@ -31,6 +31,7 @@
 #include <limits.h>
 
 #include "libkmod.h"
+#include "libkmod-array.h"
 
 static int log_priority = LOG_CRIT;
 static int use_syslog = 0;
@@ -487,6 +488,8 @@ static int rmmod_all(struct kmod_ctx *ctx, char **args, int nargs)
        return err;
 }
 
+#define INSMOD_RECURSION_STEP 15
+
 static int concat_options(const char *conf_opts, const char *extra_opts,
                                                                char **opts)
 {
@@ -541,18 +544,64 @@ static int insmod_do_insert_module(struct kmod_module *mod, const char *opts)
 
 }
 
+static bool insmod_recursion_has_loop(struct kmod_module *mod,
+                                               struct array *recursion)
+{
+       unsigned int i;
+
+       /*
+        * Don't check every time to not impact normal use cases. If the
+        * recursion hits INSMOD_RECURSION_STEP, then search loop in
+        * @recursion.
+        */
+       if ((recursion->count + 1) % INSMOD_RECURSION_STEP != 0)
+               return false;
+
+       for (i = 0; i < recursion->count; i++) {
+               if (recursion->array[i] != mod)
+                       continue;
+
+               ERR("Dependency loop detected while inserting '%s'. Operation aborted.\n",
+                                               kmod_module_get_name(mod));
+
+               for (; i < recursion->count; i++)
+                       ERR("\t%s\n", kmod_module_get_name(recursion->array[i]));
+
+               return true;
+       }
+
+       return false;
+}
+
 static int insmod_do_module(struct kmod_module *mod, const char *extra_opts,
-                                                       bool do_dependencies);
+                               bool do_dependencies, struct array *recursion);
 
 static int insmod_do_deps_list(struct kmod_list *list,
-                                               bool stop_on_errors)
+                               bool stop_on_errors, struct array *recursion)
 {
        struct kmod_list *l;
+       struct kmod_module *m;
+       int r;
+
+       if (list == NULL)
+               return 0;
+
+       m = kmod_module_get_module(list);
+       r = insmod_recursion_has_loop(m, recursion);
+       kmod_module_unref(m);
+
+       if (r)
+               return -ELOOP;
 
        kmod_list_foreach(l, list) {
-               struct kmod_module *m = kmod_module_get_module(l);
-               int r = insmod_do_module(m, NULL, false);
+               m = kmod_module_get_module(l);
+               array_append(recursion, m);
+               r = insmod_do_module(m, NULL, false, recursion);
                kmod_module_unref(m);
+               array_pop(recursion);
+
+               if (r == -ELOOP)
+                       return r;
 
                if (r < 0 && stop_on_errors)
                        return r;
@@ -562,7 +611,7 @@ static int insmod_do_deps_list(struct kmod_list *list,
 }
 
 static int insmod_do_module(struct kmod_module *mod, const char *extra_opts,
-                                                       bool do_dependencies)
+                               bool do_dependencies, struct array *recursion)
 {
        const char *modname = kmod_module_get_name(mod);
        const char *conf_opts = kmod_module_get_options(mod);
@@ -612,12 +661,14 @@ static int insmod_do_module(struct kmod_module *mod, const char *extra_opts,
                goto error;
        }
 
-       insmod_do_deps_list(pre, false);
+       err = insmod_do_deps_list(pre, false, recursion);
+       if (err == -ELOOP)
+               goto error;
 
        if (do_dependencies) {
                struct kmod_list *deps = kmod_module_get_dependencies(mod);
 
-               err = insmod_do_deps_list(deps, true);
+               err = insmod_do_deps_list(deps, true, recursion);
                if (err < 0)
                        goto error;
        }
@@ -633,7 +684,7 @@ static int insmod_do_module(struct kmod_module *mod, const char *extra_opts,
        if (err < 0)
                goto error;
 
-       insmod_do_deps_list(post, false);
+       err = insmod_do_deps_list(post, false, recursion);
 
 error:
        kmod_module_unref_list(pre);
@@ -647,6 +698,7 @@ static int insmod_path(struct kmod_ctx *ctx, const char *path,
                                                const char *extra_options)
 {
        struct kmod_module *mod;
+       struct array recursion;
        int err;
 
        err = kmod_module_new_from_path(ctx, path, &mod);
@@ -654,8 +706,12 @@ static int insmod_path(struct kmod_ctx *ctx, const char *path,
                LOG("Module %s not found.\n", path);
                return err;
        }
-       err = insmod_do_module(mod, extra_options, true);
+
+       array_init(&recursion, INSMOD_RECURSION_STEP);
+       err = insmod_do_module(mod, extra_options, true, &recursion);
        kmod_module_unref(mod);
+       array_free_array(&recursion);
+
        return err;
 }
 
@@ -714,10 +770,17 @@ static int insmod_alias(struct kmod_ctx *ctx, const char *alias,
 
        kmod_list_foreach(l, list) {
                struct kmod_module *mod = kmod_module_get_module(l);
+
                if (lookup_only)
                        printf("%s\n", kmod_module_get_name(mod));
-               else
-                       err = insmod_do_module(mod, extra_options, true);
+               else {
+                       struct array recursion;
+
+                       array_init(&recursion, INSMOD_RECURSION_STEP);
+                       err = insmod_do_module(mod, extra_options, true,
+                                                               &recursion);
+                       array_free_array(&recursion);
+               }
                kmod_module_unref(mod);
                if (err < 0)
                        break;