include/linux/jump_label.h | 2 ++ include/linux/moduleparam.h | 6 ++++++ kernel/params.c | 35 +++++++++++++++++++++++++++++++++++ 3 files changed, 43 insertions(+)
Static keys can now be a module parameter, e.g.
module_param_named(foo, foo.key, static_key_t, 0644)
bcachefs is now using this.
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: linux-modules@vger.kernel.org
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
include/linux/jump_label.h | 2 ++
include/linux/moduleparam.h | 6 ++++++
kernel/params.c | 35 +++++++++++++++++++++++++++++++++++
3 files changed, 43 insertions(+)
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index fdb79dd1ebd8..0fc9b71db56f 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -107,6 +107,8 @@ struct static_key {
#endif /* CONFIG_JUMP_LABEL */
};
+typedef struct static_key static_key_t;
+
#endif /* __ASSEMBLY__ */
#ifdef CONFIG_JUMP_LABEL
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index bfb85fd13e1f..2494e7e67453 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -488,6 +488,12 @@ extern int param_set_bint(const char *val, const struct kernel_param *kp);
#define param_get_bint param_get_int
#define param_check_bint param_check_int
+/* A static key, which can only be set like a bool */
+extern const struct kernel_param_ops param_ops_static_key_t;
+extern int param_set_static_key_t(const char *val, const struct kernel_param *kp);
+extern int param_get_static_key_t(char *buffer, const struct kernel_param *kp);
+#define param_check_static_key_t(name, p) __param_check(name, p, struct static_key)
+
/**
* module_param_array - a parameter which is an array of some type
* @name: the name of the array variable
diff --git a/kernel/params.c b/kernel/params.c
index 2509f216c9f3..991f49e138e7 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -14,6 +14,7 @@
#include <linux/overflow.h>
#include <linux/security.h>
#include <linux/slab.h>
+#include <linux/static_key.h>
#include <linux/string.h>
#ifdef CONFIG_SYSFS
@@ -412,6 +413,40 @@ const struct kernel_param_ops param_ops_bint = {
};
EXPORT_SYMBOL(param_ops_bint);
+int param_set_static_key_t(const char *val, const struct kernel_param *kp)
+{
+ /* Match bool exactly, by re-using it. */
+ struct kernel_param boolkp = *kp;
+ bool v;
+ int ret;
+
+ boolkp.arg = &v;
+
+ ret = param_set_bool(val, &boolkp);
+ if (ret)
+ return ret;
+ if (v)
+ static_key_enable(kp->arg);
+ else
+ static_key_disable(kp->arg);
+ return 0;
+}
+EXPORT_SYMBOL(param_set_static_key_t);
+
+int param_get_static_key_t(char *buffer, const struct kernel_param *kp)
+{
+ struct static_key *key = kp->arg;
+ return sprintf(buffer, "%c\n", static_key_enabled(key) ? 'N' : 'Y');
+}
+EXPORT_SYMBOL(param_get_static_key_t);
+
+const struct kernel_param_ops param_ops_static_key_t = {
+ .flags = KERNEL_PARAM_OPS_FL_NOARG,
+ .set = param_set_static_key_t,
+ .get = param_get_static_key_t,
+};
+EXPORT_SYMBOL(param_ops_static_key_t);
+
/* We break the rule and mangle the string. */
static int param_array(struct module *mod,
const char *name,
--
2.49.0
Le 10/05/2025 à 23:01, Kent Overstreet a écrit :
> Static keys can now be a module parameter, e.g.
>
> module_param_named(foo, foo.key, static_key_t, 0644)
>
> bcachefs is now using this.
>
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Cc: Petr Pavlu <petr.pavlu@suse.com>
> Cc: Sami Tolvanen <samitolvanen@google.com>
> Cc: Daniel Gomez <da.gomez@samsung.com>
> Cc: linux-modules@vger.kernel.org
> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
> ---
> include/linux/jump_label.h | 2 ++
> include/linux/moduleparam.h | 6 ++++++
> kernel/params.c | 35 +++++++++++++++++++++++++++++++++++
> 3 files changed, 43 insertions(+)
>
> diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
> index fdb79dd1ebd8..0fc9b71db56f 100644
> --- a/include/linux/jump_label.h
> +++ b/include/linux/jump_label.h
> @@ -107,6 +107,8 @@ struct static_key {
> #endif /* CONFIG_JUMP_LABEL */
> };
>
> +typedef struct static_key static_key_t;
> +
Please read https://docs.kernel.org/process/coding-style.html#typedefs
I can't see the reason for a new typedef here. If there is a valid
reason please explain in the commit message.
Christophe
On Tue, May 13, 2025 at 07:51:57PM +0200, Christophe Leroy wrote:
>
>
> Le 10/05/2025 à 23:01, Kent Overstreet a écrit :
> > Static keys can now be a module parameter, e.g.
> >
> > module_param_named(foo, foo.key, static_key_t, 0644)
> >
> > bcachefs is now using this.
> >
> > Cc: Luis Chamberlain <mcgrof@kernel.org>
> > Cc: Petr Pavlu <petr.pavlu@suse.com>
> > Cc: Sami Tolvanen <samitolvanen@google.com>
> > Cc: Daniel Gomez <da.gomez@samsung.com>
> > Cc: linux-modules@vger.kernel.org
> > Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
> > ---
> > include/linux/jump_label.h | 2 ++
> > include/linux/moduleparam.h | 6 ++++++
> > kernel/params.c | 35 +++++++++++++++++++++++++++++++++++
> > 3 files changed, 43 insertions(+)
> >
> > diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
> > index fdb79dd1ebd8..0fc9b71db56f 100644
> > --- a/include/linux/jump_label.h
> > +++ b/include/linux/jump_label.h
> > @@ -107,6 +107,8 @@ struct static_key {
> > #endif /* CONFIG_JUMP_LABEL */
> > };
> > +typedef struct static_key static_key_t;
> > +
>
> Please read https://docs.kernel.org/process/coding-style.html#typedefs
>
> I can't see the reason for a new typedef here. If there is a valid reason
> please explain in the commit message.
You can't token paste with a type that's two tokens - that's basic C.
On 5/10/25 23:01, Kent Overstreet wrote:
> Static keys can now be a module parameter, e.g.
>
> module_param_named(foo, foo.key, static_key_t, 0644)
>
> bcachefs is now using this.
>
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Cc: Petr Pavlu <petr.pavlu@suse.com>
> Cc: Sami Tolvanen <samitolvanen@google.com>
> Cc: Daniel Gomez <da.gomez@samsung.com>
> Cc: linux-modules@vger.kernel.org
Please Cc also the "STATIC BRANCH/CALL" folks on the next version.
> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
> ---
> include/linux/jump_label.h | 2 ++
> include/linux/moduleparam.h | 6 ++++++
> kernel/params.c | 35 +++++++++++++++++++++++++++++++++++
> 3 files changed, 43 insertions(+)
>
> diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
> index fdb79dd1ebd8..0fc9b71db56f 100644
> --- a/include/linux/jump_label.h
> +++ b/include/linux/jump_label.h
> @@ -107,6 +107,8 @@ struct static_key {
> #endif /* CONFIG_JUMP_LABEL */
> };
>
> +typedef struct static_key static_key_t;
> +
> #endif /* __ASSEMBLY__ */
>
> #ifdef CONFIG_JUMP_LABEL
> diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
> index bfb85fd13e1f..2494e7e67453 100644
> --- a/include/linux/moduleparam.h
> +++ b/include/linux/moduleparam.h
The module_param() macro in this file has a kernel-doc that describes
all currently supported standard types:
* Standard types are:
* byte, hexint, short, ushort, int, uint, long, ulong
* charp: a character pointer
* bool: a bool, values 0/1, y/n, Y/N.
* invbool: the above, only sense-reversed (N = true).
The static_key_t should be added to this list.
> @@ -488,6 +488,12 @@ extern int param_set_bint(const char *val, const struct kernel_param *kp);
> #define param_get_bint param_get_int
> #define param_check_bint param_check_int
>
> +/* A static key, which can only be set like a bool */
> +extern const struct kernel_param_ops param_ops_static_key_t;
> +extern int param_set_static_key_t(const char *val, const struct kernel_param *kp);
> +extern int param_get_static_key_t(char *buffer, const struct kernel_param *kp);
> +#define param_check_static_key_t(name, p) __param_check(name, p, struct static_key)
> +
> /**
> * module_param_array - a parameter which is an array of some type
> * @name: the name of the array variable
> diff --git a/kernel/params.c b/kernel/params.c
> index 2509f216c9f3..991f49e138e7 100644
> --- a/kernel/params.c
> +++ b/kernel/params.c
> @@ -14,6 +14,7 @@
> #include <linux/overflow.h>
> #include <linux/security.h>
> #include <linux/slab.h>
> +#include <linux/static_key.h>
> #include <linux/string.h>
>
> #ifdef CONFIG_SYSFS
> @@ -412,6 +413,40 @@ const struct kernel_param_ops param_ops_bint = {
> };
> EXPORT_SYMBOL(param_ops_bint);
>
> +int param_set_static_key_t(const char *val, const struct kernel_param *kp)
> +{
> + /* Match bool exactly, by re-using it. */
> + struct kernel_param boolkp = *kp;
> + bool v;
> + int ret;
> +
> + boolkp.arg = &v;
> +
> + ret = param_set_bool(val, &boolkp);
> + if (ret)
> + return ret;
> + if (v)
> + static_key_enable(kp->arg);
> + else
> + static_key_disable(kp->arg);
> + return 0;
> +}
> +EXPORT_SYMBOL(param_set_static_key_t);
> +
> +int param_get_static_key_t(char *buffer, const struct kernel_param *kp)
> +{
> + struct static_key *key = kp->arg;
> + return sprintf(buffer, "%c\n", static_key_enabled(key) ? 'N' : 'Y');
The 'N'/'Y' values are the other way around.
> +}
> +EXPORT_SYMBOL(param_get_static_key_t);
> +
> +const struct kernel_param_ops param_ops_static_key_t = {
> + .flags = KERNEL_PARAM_OPS_FL_NOARG,
> + .set = param_set_static_key_t,
> + .get = param_get_static_key_t,
> +};
> +EXPORT_SYMBOL(param_ops_static_key_t);
> +
> /* We break the rule and mangle the string. */
> static int param_array(struct module *mod,
> const char *name,
--
Thanks
Petr
On Mon, May 12, 2025 at 03:51:00PM +0200, Petr Pavlu wrote:
> On 5/10/25 23:01, Kent Overstreet wrote:
> > Static keys can now be a module parameter, e.g.
> >
> > module_param_named(foo, foo.key, static_key_t, 0644)
> >
> > bcachefs is now using this.
> >
> > Cc: Luis Chamberlain <mcgrof@kernel.org>
> > Cc: Petr Pavlu <petr.pavlu@suse.com>
> > Cc: Sami Tolvanen <samitolvanen@google.com>
> > Cc: Daniel Gomez <da.gomez@samsung.com>
> > Cc: linux-modules@vger.kernel.org
>
> Please Cc also the "STATIC BRANCH/CALL" folks on the next version.
>
> > Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
> > ---
> > include/linux/jump_label.h | 2 ++
> > include/linux/moduleparam.h | 6 ++++++
> > kernel/params.c | 35 +++++++++++++++++++++++++++++++++++
> > 3 files changed, 43 insertions(+)
> >
> > diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
> > index fdb79dd1ebd8..0fc9b71db56f 100644
> > --- a/include/linux/jump_label.h
> > +++ b/include/linux/jump_label.h
> > @@ -107,6 +107,8 @@ struct static_key {
> > #endif /* CONFIG_JUMP_LABEL */
> > };
> >
> > +typedef struct static_key static_key_t;
> > +
> > #endif /* __ASSEMBLY__ */
> >
> > #ifdef CONFIG_JUMP_LABEL
> > diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
> > index bfb85fd13e1f..2494e7e67453 100644
> > --- a/include/linux/moduleparam.h
> > +++ b/include/linux/moduleparam.h
>
> The module_param() macro in this file has a kernel-doc that describes
> all currently supported standard types:
>
> * Standard types are:
> * byte, hexint, short, ushort, int, uint, long, ulong
> * charp: a character pointer
> * bool: a bool, values 0/1, y/n, Y/N.
> * invbool: the above, only sense-reversed (N = true).
>
> The static_key_t should be added to this list.
>
> > @@ -488,6 +488,12 @@ extern int param_set_bint(const char *val, const struct kernel_param *kp);
> > #define param_get_bint param_get_int
> > #define param_check_bint param_check_int
> >
> > +/* A static key, which can only be set like a bool */
> > +extern const struct kernel_param_ops param_ops_static_key_t;
> > +extern int param_set_static_key_t(const char *val, const struct kernel_param *kp);
> > +extern int param_get_static_key_t(char *buffer, const struct kernel_param *kp);
> > +#define param_check_static_key_t(name, p) __param_check(name, p, struct static_key)
> > +
> > /**
> > * module_param_array - a parameter which is an array of some type
> > * @name: the name of the array variable
> > diff --git a/kernel/params.c b/kernel/params.c
> > index 2509f216c9f3..991f49e138e7 100644
> > --- a/kernel/params.c
> > +++ b/kernel/params.c
> > @@ -14,6 +14,7 @@
> > #include <linux/overflow.h>
> > #include <linux/security.h>
> > #include <linux/slab.h>
> > +#include <linux/static_key.h>
> > #include <linux/string.h>
> >
> > #ifdef CONFIG_SYSFS
> > @@ -412,6 +413,40 @@ const struct kernel_param_ops param_ops_bint = {
> > };
> > EXPORT_SYMBOL(param_ops_bint);
> >
> > +int param_set_static_key_t(const char *val, const struct kernel_param *kp)
> > +{
> > + /* Match bool exactly, by re-using it. */
> > + struct kernel_param boolkp = *kp;
> > + bool v;
> > + int ret;
> > +
> > + boolkp.arg = &v;
> > +
> > + ret = param_set_bool(val, &boolkp);
> > + if (ret)
> > + return ret;
> > + if (v)
> > + static_key_enable(kp->arg);
> > + else
> > + static_key_disable(kp->arg);
> > + return 0;
> > +}
> > +EXPORT_SYMBOL(param_set_static_key_t);
> > +
> > +int param_get_static_key_t(char *buffer, const struct kernel_param *kp)
> > +{
> > + struct static_key *key = kp->arg;
> > + return sprintf(buffer, "%c\n", static_key_enabled(key) ? 'N' : 'Y');
>
> The 'N'/'Y' values are the other way around.
Thanks, fixed these
© 2016 - 2026 Red Hat, Inc.