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author | Rusty Russell <rusty@rustcorp.com.au> | 2010-08-11 23:04:19 -0600 |
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committer | Rusty Russell <rusty@rustcorp.com.au> | 2010-08-11 23:04:20 +0930 |
commit | 907b29eb41aa604477a655bff7345731da94514d (patch) | |
tree | 12a7142ffa81a65da204384dfa26365d30803735 /include/linux/moduleparam.h | |
parent | 914dcaa84c53f2c3efa6016efcae13fd92a8a17c (diff) | |
download | linux-907b29eb41aa604477a655bff7345731da94514d.tar.gz linux-907b29eb41aa604477a655bff7345731da94514d.tar.bz2 linux-907b29eb41aa604477a655bff7345731da94514d.zip |
param: locking for kernel parameters
There may be cases (most obviously, sysfs-writable charp parameters) where
a module needs to prevent sysfs access to parameters.
Rather than express this in terms of a big lock, the functions are
expressed in terms of what they protect against. This is clearer, esp.
if the implementation changes to a module-level or even param-level lock.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Tested-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Diffstat (limited to 'include/linux/moduleparam.h')
-rw-r--r-- | include/linux/moduleparam.h | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index 6d48831fe7d2..ca74a3402d63 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -130,6 +130,62 @@ __check_old_set_param(int (*oldset)(const char *, struct kernel_param *)) #define module_param(name, type, perm) \ module_param_named(name, name, type, perm) +/** + * kparam_block_sysfs_write - make sure a parameter isn't written via sysfs. + * @name: the name of the parameter + * + * There's no point blocking write on a paramter that isn't writable via sysfs! + */ +#define kparam_block_sysfs_write(name) \ + do { \ + BUG_ON(!(__param_##name.perm & 0222)); \ + __kernel_param_lock(); \ + } while (0) + +/** + * kparam_unblock_sysfs_write - allows sysfs to write to a parameter again. + * @name: the name of the parameter + */ +#define kparam_unblock_sysfs_write(name) \ + do { \ + BUG_ON(!(__param_##name.perm & 0222)); \ + __kernel_param_unlock(); \ + } while (0) + +/** + * kparam_block_sysfs_read - make sure a parameter isn't read via sysfs. + * @name: the name of the parameter + * + * This also blocks sysfs writes. + */ +#define kparam_block_sysfs_read(name) \ + do { \ + BUG_ON(!(__param_##name.perm & 0444)); \ + __kernel_param_lock(); \ + } while (0) + +/** + * kparam_unblock_sysfs_read - allows sysfs to read a parameter again. + * @name: the name of the parameter + */ +#define kparam_unblock_sysfs_read(name) \ + do { \ + BUG_ON(!(__param_##name.perm & 0444)); \ + __kernel_param_unlock(); \ + } while (0) + +#ifdef CONFIG_SYSFS +extern void __kernel_param_lock(void); +extern void __kernel_param_unlock(void); +#else +static inline void __kernel_param_lock(void) +{ +} +static inline void __kernel_param_unlock(void) +{ +} +#endif + #ifndef MODULE /** * core_param - define a historical core kernel parameter. |