Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH 14/29] params: Add static key module param | Date | Fri, 22 Mar 2013 18:25:08 -0700 |
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From: Andi Kleen <ak@linux.intel.com>
Add a module param type for uint static keys. Useful for time critical flags.
Cc: rusty@rustcorp.co.au Signed-off-by: Andi Kleen <ak@linux.intel.com> --- include/linux/moduleparam.h | 6 ++++++ kernel/params.c | 35 +++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+), 0 deletions(-)
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index e3c41af..ac815d2 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -398,6 +398,12 @@ extern int param_set_bint(const char *val, const struct kernel_param *kp); extern struct kernel_param_ops param_ops_percpu_uint; #define param_check_percpu_uint(name, p) param_check_uint +/* Static key module params. Useful for time critical flags. */ +struct static_key; +extern struct kernel_param_ops param_ops_static_key; +#define param_check_static_key(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 1a8a1ca..68f9482 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -23,6 +23,7 @@ #include <linux/err.h> #include <linux/slab.h> #include <linux/ctype.h> +#include <linux/jump_label.h> /* Protects all parameters, and incidentally kmalloced_param list. */ static DEFINE_MUTEX(param_lock); @@ -527,6 +528,40 @@ struct kernel_param_ops param_ops_percpu_uint = { }; EXPORT_SYMBOL(param_ops_percpu_uint); +/* Static key module params. Like a bool, but allows patching the jumps. */ + +/* Noone else should change */ +static int param_static_key_set(const char *val, const struct kernel_param *kp) +{ + static DEFINE_SPINLOCK(lock); + bool l; + struct static_key *key = (struct static_key *)(kp->arg); + int ret = strtobool(val, &l); + + if (ret < 0) + return ret; + /* Work around racy static key interface */ + spin_lock(&lock); + if (l && !atomic_read(&key->enabled)) + static_key_slow_inc(key); + if (!l && atomic_read(&key->enabled)) + static_key_slow_dec(key); + spin_unlock(&lock); + return ret; +} + +static int param_static_key_get(char *buffer, const struct kernel_param *kp) +{ + struct static_key *key = kp->arg; + return sprintf(buffer, "%u", atomic_read(&key->enabled) > 0); +} + +struct kernel_param_ops param_ops_static_key = { + .set = param_static_key_set, + .get = param_static_key_get, +}; +EXPORT_SYMBOL(param_ops_static_key); + /* sysfs output in /sys/modules/XYZ/parameters/ */ #define to_module_attr(n) container_of(n, struct module_attribute, attr) #define to_module_kobject(n) container_of(n, struct module_kobject, kobj) -- 1.7.7.6
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