module: Add flag to allow mod params to have no arguments

Currently the params.c code allows only two "set" functions to have
no arguments. If a parameter does not have an argument, then it
looks at the set function and tests if it is either param_set_bool()
or param_set_bint(). If it is not one of these functions, then it
fails the loading of the module.

But there may be module parameters that have different set functions
and still allow no arguments. But unless each of these cases adds
their function to the if statement, it wont be allowed to have no
arguments. This method gets rather messing and does not scale.

Instead, introduce a flags field to the kernel_param_ops, where if
the flag KERNEL_PARAM_FL_NOARG is set, the parameter will not fail
if it does not contain an argument. It will be expected that the
corresponding set function can handle a NULL pointer as "val".

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 4 insertions, 2 deletions

diff --git a/kernel/params.c b/kernel/params.c
index 59f7ac7bec04..ec4299cfade8 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -103,8 +103,8 @@ static int parse_one(char *param,
                             || params[i].level > max_level)
                                 return 0;
                         /* No one handled NULL, so do it here. */
-                        if (!val && params[i].ops->set != param_set_bool
-                            && params[i].ops->set != param_set_bint)
+                        if (!val &&
+                            !(params[i].ops->flags & KERNEL_PARAM_FL_NOARG))
                                 return -EINVAL;
                         pr_debug("handling %s with %p\n", param,
                                 params[i].ops->set);
@@ -320,6 +320,7 @@ int param_get_bool(char *buffer, const struct kernel_param *kp)
 EXPORT_SYMBOL(param_get_bool);
 
 struct kernel_param_ops param_ops_bool = {
+        .flags = KERNEL_PARAM_FL_NOARG,
         .set = param_set_bool,
         .get = param_get_bool,
 };
@@ -370,6 +371,7 @@ int param_set_bint(const char *val, const struct kernel_param *kp)
 EXPORT_SYMBOL(param_set_bint);
 
 struct kernel_param_ops param_ops_bint = {
+        .flags = KERNEL_PARAM_FL_NOARG,
         .set = param_set_bint,
         .get = param_get_int,
 };