module_param: allow 'bool' module_params to be bool, not just int.

Impact: API cleanup

For historical reasons, 'bool' parameters must be an int, not a bool.
But there are around 600 users, so a conversion seems like useless churn.

So we use __same_type() to distinguish, and handle both cases.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 49 insertions, 16 deletions

diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 009a5f768768..6547c3cdbc4c 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -38,6 +38,7 @@ typedef int (*param_get_fn)(char *buffer, struct kernel_param *kp);
 
 /* Flag bits for kernel_param.flags */
 #define KPARAM_KMALLOCED        1
+#define KPARAM_ISBOOL           2
 
 struct kernel_param {
         const char *name;
@@ -83,7 +84,7 @@ struct kparam_array
    parameters.  perm sets the visibility in sysfs: 000 means it's
    not there, read bits mean it's readable, write bits mean it's
    writable. */
-#define __module_param_call(prefix, name, set, get, arg, perm)          \
+#define __module_param_call(prefix, name, set, get, arg, isbool, perm)  \
         /* Default value instead of permissions? */                     \
         static int __param_perm_check_##name __attribute__((unused)) =  \
         BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2))  \
@@ -92,10 +93,13 @@ struct kparam_array
         static struct kernel_param __moduleparam_const __param_##name   \
         __used                                                          \
     __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
-        = { __param_str_##name, perm, 0, set, get, { arg } }
+        = { __param_str_##name, perm, isbool ? KPARAM_ISBOOL : 0,       \
+            set, get, { arg } }
 
 #define module_param_call(name, set, get, arg, perm)                          \
-        __module_param_call(MODULE_PARAM_PREFIX, name, set, get, arg, perm)
+        __module_param_call(MODULE_PARAM_PREFIX,                              \
+                            name, set, get, arg,                              \
+                            __same_type(*(arg), bool), perm)
 
 /* Helper functions: type is byte, short, ushort, int, uint, long,
    ulong, charp, bool or invbool, or XXX if you define param_get_XXX,
@@ -124,15 +128,16 @@ struct kparam_array
 #define core_param(name, var, type, perm)                               \
         param_check_##type(name, &(var));                               \
         __module_param_call("", name, param_set_##type, param_get_##type, \
-                            &var, perm)
+                            &var, __same_type(var, bool), perm)
 #endif /* !MODULE */
 
 /* Actually copy string: maxlen param is usually sizeof(string). */
 #define module_param_string(name, string, len, perm)                    \
         static const struct kparam_string __param_string_##name         \
                 = { len, string };                                      \
-        module_param_call(name, param_set_copystring, param_get_string, \
-                          .str = &__param_string_##name, perm);         \
+        __module_param_call(MODULE_PARAM_PREFIX, name,                  \
+                            param_set_copystring, param_get_string,     \
+                            .str = &__param_string_##name, 0, perm);    \
         __MODULE_PARM_TYPE(name, "string")
 
 /* Called on module insert or kernel boot */
@@ -190,9 +195,16 @@ extern int param_set_charp(const char *val, struct kernel_param *kp);
 extern int param_get_charp(char *buffer, struct kernel_param *kp);
 #define param_check_charp(name, p) __param_check(name, p, char *)
 
+/* For historical reasons "bool" parameters can be (unsigned) "int". */
 extern int param_set_bool(const char *val, struct kernel_param *kp);
 extern int param_get_bool(char *buffer, struct kernel_param *kp);
-#define param_check_bool(name, p) __param_check(name, p, int)
+#define param_check_bool(name, p)                                       \
+        static inline void __check_##name(void)                         \
+        {                                                               \
+                BUILD_BUG_ON(!__same_type(*(p), bool) &&                \
+                             !__same_type(*(p), unsigned int) &&        \
+                             !__same_type(*(p), int));                  \
+        }
 
 extern int param_set_invbool(const char *val, struct kernel_param *kp);
 extern int param_get_invbool(char *buffer, struct kernel_param *kp);
@@ -203,8 +215,10 @@ extern int param_get_invbool(char *buffer, struct kernel_param *kp);
         static const struct kparam_array __param_arr_##name             \
         = { ARRAY_SIZE(array), nump, param_set_##type, param_get_##type,\
             sizeof(array[0]), array };                                  \
-        module_param_call(name, param_array_set, param_array_get,       \
-                          .arr = &__param_arr_##name, perm);            \
+        __module_param_call(MODULE_PARAM_PREFIX, name,                  \
+                            param_array_set, param_array_get,           \
+                            .arr = &__param_arr_##name,                 \
+                            __same_type(array[0], bool), perm);         \
         __MODULE_PARM_TYPE(name, "array of " #type)
 
 #define module_param_array(name, type, nump, perm)              \
diff --git a/kernel/params.c b/kernel/params.c
index b4660dc13dbc..7f6912ced2ba 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -238,35 +238,54 @@ int param_get_charp(char *buffer, struct kernel_param *kp)
         return sprintf(buffer, "%s", *((char **)kp->arg));
 }
 
+/* Actually could be a bool or an int, for historical reasons. */
 int param_set_bool(const char *val, struct kernel_param *kp)
 {
+        bool v;
+
         /* No equals means "set"... */
         if (!val) val = "1";
 
         /* One of =[yYnN01] */
         switch (val[0]) {
         case 'y': case 'Y': case '1':
-                *(int *)kp->arg = 1;
-                return 0;
+                v = true;
+                break;
         case 'n': case 'N': case '0':
-                *(int *)kp->arg = 0;
-                return 0;
+                v = false;
+                break;
+        default:
+                return -EINVAL;
         }
-        return -EINVAL;
+
+        if (kp->flags & KPARAM_ISBOOL)
+                *(bool *)kp->arg = v;
+        else
+                *(int *)kp->arg = v;
+        return 0;
 }
 
 int param_get_bool(char *buffer, struct kernel_param *kp)
 {
+        bool val;
+        if (kp->flags & KPARAM_ISBOOL)
+                val = *(bool *)kp->arg;
+        else
+                val = *(int *)kp->arg;
+
         /* Y and N chosen as being relatively non-coder friendly */
-        return sprintf(buffer, "%c", (*(int *)kp->arg) ? 'Y' : 'N');
+        return sprintf(buffer, "%c", val ? 'Y' : 'N');
 }
 
+/* This one must be bool. */
 int param_set_invbool(const char *val, struct kernel_param *kp)
 {
-        int boolval, ret;
+        int ret;
+        bool boolval;
         struct kernel_param dummy;
 
         dummy.arg = &boolval;
+        dummy.flags = KPARAM_ISBOOL;
         ret = param_set_bool(val, &dummy);
         if (ret == 0)
                 *(bool *)kp->arg = !boolval;