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

[Harish Jenny Kandiga Nagaraj <harish_kandiga@mentor.com>]

On Thursday 19 February 2015 07:32 PM, Harish Jenny Kandiga Nagaraj wrote:
> On Thursday 19 February 2015 06:13 PM, Lucas De Marchi wrote:
>> On Thu, Feb 19, 2015 at 10:32 AM, Harish Jenny Kandiga Nagaraj
>> <harish_kandiga@mentor.com> wrote:
>>> 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@mentor.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;
>> no. I guess this doesn't pass the proposed test:
>>
>> 1)
>> kmod_module_new_from_name(ctx, "vt", &mod);
>> kmod_module_get_initstate(mod, &state);
>>
>> this must return builtin
>>
>> 2)
>> kmod_module_new_from_lookup(ctx, "vt", &list);
>> ... (get mod from list)
>> kmod_module_get_initstate(mod, &state);
>>
>> this must return builtin as well.
>>
>> I suggest you add a kmod_module_is_builtin() which does the lookup
>> (but doesn't increase the module refcount, i.e. doesn't call
>> new_module_xxxx()) iff it's not already done. For this you will need
>> to change mod->builtin to an enum: enum { XXXX_UNKNOWN, XXXX_NO,
>> XXXX_YES } then you do:
>>
>> bool kmod_module_is_builtin(mod)  (don't export this function)
>> {
>>         if (mod->XXXX_UNKNOWN) {
>>               ... lookup in builtin index
>>         }
>>         return mod->builtin == XXXX_YES;
>> }
>>
>> then you change the users of mod->builtin.
>>
>
> something like this ?
>
>
> diff --git a/libkmod/libkmod-internal.h b/libkmod/libkmod-internal.h
> index 417f232..f6ffd3e 100644
> --- a/libkmod/libkmod-internal.h
> +++ b/libkmod/libkmod-internal.h
> @@ -46,6 +46,13 @@ static _always_inline_ _printf_format_(2, 3) void
>  #  endif
>  #endif
>  
> +/* Flags to kmod_builtin_status() */
> +enum kmod_builtin_status {
> +    KMOD_BUILTIN_UNKNOWN = 0,
> +    KMOD_BUILTIN_NO = 1,
> +    KMOD_BUILTIN_YES = 2
> +};
> +
>  void kmod_log(const struct kmod_ctx *ctx,
>          int priority, const char *file, int line, const char *fn,
>          const char *format, ...) __attribute__((format(printf, 6, 7))) __attribute__((nonnull(1, 3, 5)));
> @@ -92,6 +99,7 @@ int kmod_lookup_alias_from_symbols_file(struct kmod_ctx *ctx, const char *name,
>  int kmod_lookup_alias_from_aliases_file(struct kmod_ctx *ctx, const char *name, struct kmod_list **list) __attribute__((nonnull(1, 2, 3)));
>  int kmod_lookup_alias_from_moddep_file(struct kmod_ctx *ctx, const char *name, struct kmod_list **list) __attribute__((nonnull(1, 2, 3)));
>  int kmod_lookup_alias_from_builtin_file(struct kmod_ctx *ctx, const char *name, struct kmod_list **list) __attribute__((nonnull(1, 2, 3)));
> +int kmod_just_lookup_alias_from_builtin_file(struct kmod_ctx *ctx, const char *name)__attribute__((nonnull(1, 2)));
>  int kmod_lookup_alias_from_commands(struct kmod_ctx *ctx, const char *name, struct kmod_list **list) __attribute__((nonnull(1, 2, 3)));
>  void kmod_set_modules_visited(struct kmod_ctx *ctx, bool visited) __attribute__((nonnull((1))));
>  void kmod_set_modules_required(struct kmod_ctx *ctx, bool required) __attribute__((nonnull((1))));
> @@ -143,9 +151,9 @@ int kmod_module_parse_depline(struct kmod_module *mod, char *line) __attribute__
>  void kmod_module_set_install_commands(struct kmod_module *mod, const char *cmd) __attribute__((nonnull(1)));
>  void kmod_module_set_remove_commands(struct kmod_module *mod, const char *cmd) __attribute__((nonnull(1)));
>  void kmod_module_set_visited(struct kmod_module *mod, bool visited) __attribute__((nonnull(1)));
> -void kmod_module_set_builtin(struct kmod_module *mod, bool builtin) __attribute__((nonnull((1))));
> +void kmod_module_set_builtin(struct kmod_module *mod, enum kmod_builtin_status builtin) __attribute__((nonnull((1))));
>  void kmod_module_set_required(struct kmod_module *mod, bool required) __attribute__((nonnull(1)));
> -
> +bool kmod_module_is_builtin(const struct kmod_module *mod);
>  
>  /* libkmod-file.c */
>  struct kmod_file *kmod_file_open(const struct kmod_ctx *ctx, const char *filename) _must_check_ __attribute__((nonnull(1,2)));
> diff --git a/libkmod/libkmod-module.c b/libkmod/libkmod-module.c
> index 19bb2ed..6b2f2f1 100644
> --- a/libkmod/libkmod-module.c
> +++ b/libkmod/libkmod-module.c
> @@ -98,7 +98,7 @@ struct kmod_module {
>       * is set. There's nothing much useful one can do with such a
>       * "module", except knowing it's builtin.
>       */
> -    bool builtin : 1;
> +    enum kmod_builtin_status builtin;
>  };
>  
>  static inline const char *path_join(const char *path, size_t prefixlen,
> @@ -210,7 +210,7 @@ void kmod_module_set_visited(struct kmod_module *mod, bool visited)
>      mod->visited = visited;
>  }
>  
> -void kmod_module_set_builtin(struct kmod_module *mod, bool builtin)
> +void kmod_module_set_builtin(struct kmod_module *mod, enum kmod_builtin_status builtin)
>  {
>      mod->builtin = builtin;
>  }
> @@ -220,6 +220,15 @@ void kmod_module_set_required(struct kmod_module *mod, bool required)
>      mod->required = required;
>  }
>  
> +bool kmod_module_is_builtin(const struct kmod_module *mod)
> +{
> +    int builtin = mod->builtin;
> +
> +    if (builtin == KMOD_BUILTIN_UNKNOWN)
> +        builtin = kmod_just_lookup_alias_from_builtin_file(mod->ctx, mod->name);
> +
> +    return mod->builtin == KMOD_BUILTIN_YES;
> +}
>  /*
>   * Memory layout with alias:
>   *
> @@ -924,7 +933,7 @@ KMOD_EXPORT int kmod_module_apply_filter(const struct kmod_ctx *ctx,
>                  module_is_blacklisted(mod))
>              continue;
>  
> -        if ((filter_type & KMOD_FILTER_BUILTIN) && mod->builtin)
> +        if ((filter_type & KMOD_FILTER_BUILTIN) && kmod_module_is_builtin(mod))
>              continue;
>  
>          node = kmod_list_append(*output, mod);
> @@ -1713,7 +1722,7 @@ KMOD_EXPORT int kmod_module_get_initstate(const struct kmod_module *mod)
>      if (mod == NULL)
>          return -ENOENT;
>  
> -    if (mod->builtin)
> +    if (kmod_module_is_builtin(mod))
>          return KMOD_MODULE_BUILTIN;
>  
>      pathlen = snprintf(path, sizeof(path),
> diff --git a/libkmod/libkmod.c b/libkmod/libkmod.c
> index 1a5a66b..d79bb12 100644
> --- a/libkmod/libkmod.c
> +++ b/libkmod/libkmod.c
> @@ -525,7 +525,7 @@ int kmod_lookup_alias_from_builtin_file(struct kmod_ctx *ctx, const char *name,
>              goto finish;
>          }
>  
> -        kmod_module_set_builtin(mod, true);
> +        kmod_module_set_builtin(mod, KMOD_BUILTIN_YES);
>          *list = kmod_list_append(*list, mod);
>          if (*list == NULL)
>              err = -ENOMEM;
> @@ -536,6 +536,39 @@ finish:
>      return err;
>  }
>  
> +int kmod_just_lookup_alias_from_builtin_file(struct kmod_ctx *ctx,
> +        const char *name) {
> +    char *line = NULL;
> +
> +    if (ctx->indexes[KMOD_INDEX_MODULES_BUILTIN]) {
> +        DBG(ctx, "use mmaped index '%s' modname=%s\n",
> +                index_files[KMOD_INDEX_MODULES_BUILTIN].fn, name);
> +        line = index_mm_search(ctx->indexes[KMOD_INDEX_MODULES_BUILTIN], name);
> +    } else {
> +        struct index_file *idx;
> +        char fn[PATH_MAX];
> +
> +        snprintf(fn, sizeof(fn), "%s/%s.bin", ctx->dirname,
> +                index_files[KMOD_INDEX_MODULES_BUILTIN].fn);
> +        DBG(ctx, "file=%s modname=%s\n", fn, name);
> +
> +        idx = index_file_open(fn);
> +        if (idx == NULL) {
> +            DBG(ctx, "could not open builtin file '%s'\n", fn);
> +            goto finish;
> +        }
> +
> +        line = index_search(idx, name);
> +        index_file_close(idx);
> +    }
> +
> +    if (line != NULL)
> +        return KMOD_BUILTIN_YES;
> +
> +finish:
> +        return KMOD_BUILTIN_NO;
> +}
> +
>  char *kmod_search_moddep(struct kmod_ctx *ctx, const char *name)
>  {
>      struct index_file *idx;
>
>
>


I guess there are some mistakes

1) return mod->builtin == KMOD_BUILTIN_YES;  should be made to
return builtin == KMOD_BUILTIN_YES;
2) S_ISDIR check needs to be removed.

Lucas,
In any case , Can this patch can be taken in sequence?
My first original patch of removing directory check can be taken first. Then the necessary changes required. (you might add as well in your free time as suggested by you)