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authorRusty Russell <rusty@rustcorp.com.au>2010-08-11 23:04:19 -0600
committerRusty Russell <rusty@rustcorp.com.au>2010-08-11 23:04:20 +0930
commit907b29eb41aa604477a655bff7345731da94514d (patch)
tree12a7142ffa81a65da204384dfa26365d30803735 /include/linux/moduleparam.h
parent914dcaa84c53f2c3efa6016efcae13fd92a8a17c (diff)
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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.h56
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.