On Sat, Apr 30, 2022 at 11:30:58AM +0100, Mauro Carvalho Chehab wrote:
Sometimes, device drivers are bound into each other via try_module_get(), making such references invisible when looking at /proc/modules or lsmod.
Add a function to allow setting up module references for such cases, and call it when try_module_get() is used.
Reviewed-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Mauro Carvalho Chehab mchehab@kernel.org
See [PATCH v2 0/2] at: https://lore.kernel.org/all/cover.1651314499.git.mchehab@kernel.org/
include/linux/module.h | 4 +++- kernel/module/main.c | 35 +++++++++++++++++++++++++++++++++-- 2 files changed, 36 insertions(+), 3 deletions(-)
diff --git a/include/linux/module.h b/include/linux/module.h index 46d4d5f2516e..836851baaad4 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -620,7 +620,9 @@ extern void __module_get(struct module *module);
/* This is the Right Way to get a module: if it fails, it's being removed,
- so pretend it's not there. */
-extern bool try_module_get(struct module *module); +extern bool __try_module_get(struct module *module, struct module *this);
+#define try_module_get(mod) __try_module_get(mod, THIS_MODULE)
extern void module_put(struct module *module);
diff --git a/kernel/module/main.c b/kernel/module/main.c index 05a42d8fcd7a..9f4416381e65 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -631,6 +631,35 @@ static int ref_module(struct module *a, struct module *b) return 0; }
+static int ref_module_dependency(struct module *mod,
struct module *this)
This can be on one line, right?
+{
- int ret;
- if (!this || !this->name) {
return -EINVAL;- }
Did you run checkpatch on this? Please do :)
- if (mod == this)
return 0;
How can this happen?
When people mistakenly call try_module_get(THIS_MODULE)? We should throw up a big warning when that happens anyway as that's always wrong.
But that's a different issue from this change, sorry for the noise.
- mutex_lock(&module_mutex);
- ret = ref_module(this, mod);
+#ifdef CONFIG_MODULE_UNLOAD
- if (ret)
goto ret;- ret = sysfs_create_link(mod->holders_dir,
&this->mkobj.kobj, this->name);
Meta comment, why do we only create links if we can unload things?
thanks,
greg k-h