[PATCH 03/11] moduleparam: Add DEFINE_KERNEL_PARAM_OPS macro family
From: Kees Cook <kees@kernel.org>
Date: 2026-05-21 13:33:26
Also in:
dmaengine, dri-devel, intel-gfx, kvm, linux-acpi, linux-arch, linux-fsdevel, linux-hardening, linux-media, linux-mm, linux-modules, linux-pci, linux-pm, linux-rdma, linux-scsi, linux-security-module, linux-serial, linux-um, linux-usb, lkml, netdev, qemu-devel, virtualization
Subsystem:
module support, the rest · Maintainers:
Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen, Linus Torvalds
Add macros that define a struct kernel_param_ops initializer through a macro so the underlying field layout can evolve without touching every call site. Three variants cover the three cases: DEFINE_KERNEL_PARAM_OPS(name, set, get) // basic DEFINE_KERNEL_PARAM_OPS_NOARG(name, set, get) // set KERNEL_PARAM_OPS_FL_NOARG DEFINE_KERNEL_PARAM_OPS_FREE(name, set, get, free) // also set .free Callers prefix their own visibility qualifiers, e.g.: static DEFINE_KERNEL_PARAM_OPS(my_ops, my_set, my_get); Also update module_param_call() and STANDARD_PARAM_DEF() to use DEFINE_KERNEL_PARAM_OPS internally so the generated ops table will go through the same macro as everything else. Subsequent commits convert all open-coded struct kernel_param_ops definitions to use these macros, in preparation for migrating to a seq_buf .get API. Signed-off-by: Kees Cook <kees@kernel.org> --- include/linux/moduleparam.h | 36 ++++++++++++++++++++++++++++++++++-- kernel/params.c | 6 ++---- 2 files changed, 36 insertions(+), 6 deletions(-)
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 075f28585074..26bf45b36d02 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h@@ -68,6 +68,39 @@ struct kernel_param_ops { void (*free)(void *arg); }; +/* + * Define a const struct kernel_param_ops initializer. Callers prefix with + * any required visibility qualifiers (typically "static"): + * + * static DEFINE_KERNEL_PARAM_OPS(my_ops, my_set, my_get); + * + * Routing the @_set and @_get function pointers through the macro + * (rather than naming the struct fields at every call site) lets the + * field layout change in one place when callbacks are migrated to a + * new signature. + */ +#define DEFINE_KERNEL_PARAM_OPS(_name, _set, _get) \ + const struct kernel_param_ops _name = { \ + .set = (_set), \ + .get = (_get), \ + } + +/* As DEFINE_KERNEL_PARAM_OPS, with KERNEL_PARAM_OPS_FL_NOARG set. */ +#define DEFINE_KERNEL_PARAM_OPS_NOARG(_name, _set, _get) \ + const struct kernel_param_ops _name = { \ + .flags = KERNEL_PARAM_OPS_FL_NOARG, \ + .set = (_set), \ + .get = (_get), \ + } + +/* As DEFINE_KERNEL_PARAM_OPS, with an additional .free callback. */ +#define DEFINE_KERNEL_PARAM_OPS_FREE(_name, _set, _get, _free) \ + const struct kernel_param_ops _name = { \ + .set = (_set), \ + .get = (_get), \ + .free = (_free), \ + } + /* * Flags available for kernel_param *
@@ -311,8 +344,7 @@ struct kparam_array * 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 }; \ + static DEFINE_KERNEL_PARAM_OPS(__param_ops_##name, _set, _get); \ __module_param_call(MODULE_PARAM_PREFIX, \ name, &__param_ops_##name, arg, perm, -1, 0)
diff --git a/kernel/params.c b/kernel/params.c
index 752721922a15..2cbad1f4dd06 100644
--- a/kernel/params.c
+++ b/kernel/params.c@@ -222,10 +222,8 @@ char *parse_args(const char *doing, return scnprintf(buffer, PAGE_SIZE, format "\n", \ *((type *)kp->arg)); \ } \ - const struct kernel_param_ops param_ops_##name = { \ - .set = param_set_##name, \ - .get = param_get_##name, \ - }; \ + DEFINE_KERNEL_PARAM_OPS(param_ops_##name, \ + param_set_##name, param_get_##name); \ EXPORT_SYMBOL(param_set_##name); \ EXPORT_SYMBOL(param_get_##name); \ EXPORT_SYMBOL(param_ops_##name)
--
2.34.1