linux-kernel - Re: [PATCH] libkmod-module: Remove directory existence check for KMOD_MODULE

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Date:	Thu, 19 Feb 2015 18:02:49 +0530
From:	Harish Jenny Kandiga Nagaraj <harish_kandiga@...tor.com>
To:	Lucas De Marchi <lucas.de.marchi@...il.com>
CC:	Rusty Russell <rusty@...tcorp.com.au>,
	linux-modules <linux-modules@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] libkmod-module: Remove directory existence check for
 KMOD_MODULE_BUILTIN


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@...tor.com> 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))
-                               return KMOD_MODULE_COMING;
+                               return mod->lookup ? KMOD_MODULE_COMING : KMOD_MODULE_BUILTIN;
                }
 
                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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