| Message ID | 20230913235407.gonna.817-kees@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] module: Clarify documentation of module_param_call() | expand |
On Wed, Sep 13, 2023 at 04:54:14PM -0700, Kees Cook wrote: > Commit 9bbb9e5a3310 ("param: use ops in struct kernel_param, rather than > get and set fns directly") added the comment that module_param_call() > was deprecated, during a large scale refactoring to bring sanity to type > casting back then. In 2017 following more cleanups, it became useful > again as it wraps a common pattern of creating an ops struct for a > given get/set pair: > > b2f270e87473 ("module: Prepare to convert all module_param_call() prototypes") > ece1996a21ee ("module: Do not paper over type mismatches in module_param_call()") > > static const struct kernel_param_ops __param_ops_##name = \ > { .flags = 0, .set = _set, .get = _get }; \ > __module_param_call(MODULE_PARAM_PREFIX, \ > name, &__param_ops_##name, arg, perm, -1, 0) > > __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1, 0) > > Many users of module_param_cb() appear to be almost universally > open-coding the same thing that module_param_call() does now. Don't > discourage[1] people from using module_param_call(): clarify the comment > to show that module_param_cb() is useful if you repeatedly use the same > pair of get/set functions. > > [1] https://lore.kernel.org/lkml/202308301546.5C789E5EC@keescook/ > > Cc: Luis Chamberlain <mcgrof@kernel.org> > Cc: Johan Hovold <johan@kernel.org> > Cc: Jessica Yu <jeyu@kernel.org> > Cc: Sagi Grimberg <sagi@grimberg.me> > Cc: Nick Desaulniers <ndesaulniers@gooogle.com> > Cc: Miguel Ojeda <ojeda@kernel.org> > Cc: Joe Perches <joe@perches.com> > Cc: linux-modules@vger.kernel.org > Reviewed-by: Miguel Ojeda <ojeda@kernel.org> > Signed-off-by: Kees Cook <keescook@chromium.org> Applied and pushed to modules-next, thanks > --- > Luis, I note that include/linux/moduleparam.h isn't in the MAINTAINERS > file pattern. Perhaps you want to use include/linux/module*.h? Sent patch! Thanks! Luis
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index 962cd41a2cb5..d4452f93d060 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -293,7 +293,11 @@ struct kparam_array = { __param_str_##name, THIS_MODULE, ops, \ VERIFY_OCTAL_PERMISSIONS(perm), level, flags, { arg } } -/* Obsolete - use module_param_cb() */ +/* + * Useful for describing a set/get pair used only once (i.e. for this + * parameter). For repeated set/get pairs (i.e. the same struct + * kernel_param_ops), use module_param_cb() instead. + */ #define module_param_call(name, _set, _get, arg, perm) \ static const struct kernel_param_ops __param_ops_##name = \ { .flags = 0, .set = _set, .get = _get }; \
Commit 9bbb9e5a3310 ("param: use ops in struct kernel_param, rather than get and set fns directly") added the comment that module_param_call() was deprecated, during a large scale refactoring to bring sanity to type casting back then. In 2017 following more cleanups, it became useful again as it wraps a common pattern of creating an ops struct for a given get/set pair: b2f270e87473 ("module: Prepare to convert all module_param_call() prototypes") ece1996a21ee ("module: Do not paper over type mismatches in module_param_call()") static const struct kernel_param_ops __param_ops_##name = \ { .flags = 0, .set = _set, .get = _get }; \ __module_param_call(MODULE_PARAM_PREFIX, \ name, &__param_ops_##name, arg, perm, -1, 0) __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1, 0) Many users of module_param_cb() appear to be almost universally open-coding the same thing that module_param_call() does now. Don't discourage[1] people from using module_param_call(): clarify the comment to show that module_param_cb() is useful if you repeatedly use the same pair of get/set functions. [1] https://lore.kernel.org/lkml/202308301546.5C789E5EC@keescook/ Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Johan Hovold <johan@kernel.org> Cc: Jessica Yu <jeyu@kernel.org> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Nick Desaulniers <ndesaulniers@gooogle.com> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Joe Perches <joe@perches.com> Cc: linux-modules@vger.kernel.org Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> --- Luis, I note that include/linux/moduleparam.h isn't in the MAINTAINERS file pattern. Perhaps you want to use include/linux/module*.h? --- include/linux/moduleparam.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)