Friendly ping ...
On 2019/7/3 10:09, Zhiqiang Liu wrote:
> From: Zhiqiang Liu <liuzhiqian...@huawei.com>
>
> Users can call ref_module func in their modules to construct
> relationships with other modules. However, the holders
> '/sys/module/<mod-name>/holders' of the target module donot include
> the users` module. So lsmod command misses detailed info of 'Used by'.
>
> When load module, the process is given as follows,
> load_module()
> -> mod_sysfs_setup()
> -> add_usage_links
> -> do_init_module
> -> mod->init()
>
> add_usage_links func creates holders of target modules linking to
> this module. If ref_module is called in mod->init() func, the usage
> links cannot be added.
>
> Here, we will add usage link of a to b's holder_dir.
>
> V1->V2:
> - remove incorrect Fixes tag
> - fix error handling of sysfs_create_link as suggested by Jessica Yu
>
> Signed-off-by: Zhiqiang Liu <liuzhiqian...@huawei.com>
> Suggested-by: Jessica Yu <j...@kernel.org>
> Reviewed-by: Kang Zhou <zhouka...@huawei.com>
> ---
> kernel/module.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 80c7c09584cf..672abce2222c 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -837,25 +837,26 @@ static int already_uses(struct module *a, struct module
> *b)
> * 'b' can walk the list to see who sourced them), and of 'a'
> * targets (so 'a' can see what modules it targets).
> */
> -static int add_module_usage(struct module *a, struct module *b)
> +static struct module_use *add_module_usage(struct module *a, struct module
> *b)
> {
> struct module_use *use;
>
> pr_debug("Allocating new usage for %s.\n", a->name);
> use = kmalloc(sizeof(*use), GFP_ATOMIC);
> if (!use)
> - return -ENOMEM;
> + return NULL;
>
> use->source = a;
> use->target = b;
> list_add(&use->source_list, &b->source_list);
> list_add(&use->target_list, &a->target_list);
> - return 0;
> + return use;
> }
>
> /* Module a uses b: caller needs module_mutex() */
> int ref_module(struct module *a, struct module *b)
> {
> + struct module_use *use;
> int err;
>
> if (b == NULL || already_uses(a, b))
> @@ -866,9 +867,18 @@ int ref_module(struct module *a, struct module *b)
> if (err)
> return err;
>
> - err = add_module_usage(a, b);
> + use = add_module_usage(a, b);
> + if (!use) {
> + module_put(b);
> + return -ENOMEM;
> + }
> +
> + err = sysfs_create_link(b->holders_dir, &a->mkobj.kobj, a->name);
> if (err) {
> module_put(b);
> + list_del(&use->source_list);
> + list_del(&use->target_list);
> + kfree(use);
> return err;
> }
> return 0;
>
