Re: [PATCH] libkmod-module: Remove directory existence check for KMOD_MODULE_BUILTIN

From: Harish Jenny Kandiga Nagaraj
Date: Thu Feb 19 2015 - 07:33:00 EST

On Thursday 19 February 2015 04:00 PM, Lucas De Marchi wrote:
> On Thu, Feb 19, 2015 at 3:49 AM, Harish Jenny Kandiga Nagaraj
> <harish_kandiga@xxxxxxxxxx> wrote:
>>> Harrish, in your patch if you just change the "return
>>> KMOD_MODULE_BUILTIN;" to "return KMOD_MODULE_COMING;" does it work?
>> Yes. Returning KMOD_MODULE_COMING instead of KMOD_MODULE_BUILTIN works. The built-in modules are handled by looking at the modules.builtin index file. Is there any chance of returning KMOD_MODULE_COMING for builti-in modules? If it does not have any impact, then the fix should be fine.
> well... you're not returning KMOD_MODULE_COMING for a builtin module.
> Having the directory /sys/module/<name> and not the initstate could be
> either that the module is builtin or that there's a race while loading
> the module and it's in the coming state. However since we use the
> index to decide if this module is builtin in the beginning of this
> function, here it can only be the second case.
> However... mod->builtin in the beginning of this function is only set
> if the module is created by a lookup rather than from name or from
> path.... maybe here we need to actually fallback to the index rather
> than the cached value, otherwise this test would fail (considering
> "vt" is builtin):
> kmod_module_new_from_name(ctx, "vt", &mod);
> kmod_module_get_initstate(mod, &state);

something like this ?

diff --git a/libkmod/libkmod-module.c b/libkmod/libkmod-module.c
index 19bb2ed..d424f3e 100644
--- a/libkmod/libkmod-module.c
+++ b/libkmod/libkmod-module.c
@@ -99,6 +99,8 @@ struct kmod_module {
* "module", except knowing it's builtin.
bool builtin : 1;
+ bool lookup : 1;

static inline const char *path_join(const char *path, size_t prefixlen,
@@ -215,6 +217,11 @@ void kmod_module_set_builtin(struct kmod_module *mod, bool builtin)
mod->builtin = builtin;

+void kmod_module_set_lookup(struct kmod_module *mod, bool lookup)
+ mod->lookup = lookup;
void kmod_module_set_required(struct kmod_module *mod, bool required)
mod->required = required;
@@ -1729,7 +1736,7 @@ KMOD_EXPORT int kmod_module_get_initstate(const struct kmod_module *mod)
struct stat st;
path[pathlen - (sizeof("/initstate") - 1)] = '\0';
if (stat(path, &st) == 0 && S_ISDIR(st.st_mode))

DBG(mod->ctx, "could not open '%s': %s\n",
diff --git a/tools/modprobe.c b/tools/modprobe.c
index 3af16c7..43288b6 100644
--- a/tools/modprobe.c
+++ b/tools/modprobe.c
@@ -549,6 +549,7 @@ static int insmod(struct kmod_ctx *ctx, const char *alias,
if (lookup_only)
printf("%s\n", kmod_module_get_name(mod));
else {
+ kmod_module_set_lookup(mod,true);
err = kmod_module_probe_insert_module(mod, flags,
extra_options, NULL, NULL, show);

>> Do I need to send a separate patch ?
> I was hoping it would be a oneliner, but it isn't. If you are going to
> send a patch, please add the necessary checks for the builtin index.
> Otherwise I can take a look on this until the end of this week.
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