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@xxxxxxxxx> > Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> > --- > > See [PATCH v2 0/2] at: https://lore.kernel.org/all/cover.1651314499.git.mchehab@xxxxxxxxxx/ > > 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
