Messages in this thread Patch in this message | | | Date | Mon, 21 Nov 2016 02:37:47 -0500 | From | Jessica Yu <> | Subject | Re: moduleparam: introduce core_param_named macro for non-modular code |
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+++ Paul Gortmaker [14/11/16 21:00 -0500]: >We have the case where module_param_named() in file "foo.c" for >parameter myparam translates that into the bootarg for the >non-modular use case as "foo.myparam=..." > >The problem exists where the use case with the filename and the >dot prefix is established, but the code is then realized to be 100% >non-modular, or is converted to non-modular. Both of the existing >macros like core_param() or setup_param() do not append such a >prefix, so a straight conversion to either will break the existing >use cases. > >Similarly, trying to embed a hard coded "foo." prefix on the name >fails cpp syntax due to the special nature of "." in code. So we add >this parallel variant for the modular --> non-modular transition to >preserve existing and documented use cases with such a prefix.
Hm, I'm not convinced we need a core_ counterpart to module_param_named (that's nearly identical), when module_param_named already implements all of the above. Plenty of non-modular code already use it (e.g. workqueue, printk), and a prefix is automatically supplied (which can be overridden) in the non-modular case. That should already meet your requirements, no?
>Cc: Jessica Yu <jeyu@redhat.com> >Cc: Rusty Russell <rusty@rustcorp.com.au> >Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> >--- > >[Marking this RFC since I don't like the fact that it still requires > non-modular code to use moduleparam.h -- one possible fix for that is > to consider moving non-modular macros to a new param.h or similar. ] > > include/linux/moduleparam.h | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > >diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h >index 52666d90ca94..4f2b92345eb5 100644 >--- a/include/linux/moduleparam.h >+++ b/include/linux/moduleparam.h >@@ -269,6 +269,23 @@ static inline void kernel_param_unlock(struct module *mod) > __module_param_call("", name, ¶m_ops_##type, &var, perm, -1, 0) > > /** >+ * core_param_named - define a module compat core kernel parameter. >+ * @name: the name of the cmdline and sysfs parameter (often the same as var) >+ * @var: the variable >+ * @type: the type of the parameter >+ * @perm: visibility in sysfs >+ * >+ * core_param_named is just like module_param_named(), but cannot be modular >+ * and it _does_ add a prefix (such as "printk."). This is for compatibility >+ * with module_param_named(), and it exists to provide boot arg compatibility >+ * with code that was previously using the modular version with the prefix. >+ */ >+#define core_param_named(name, var, type, perm) \ >+ param_check_##type(name, &(var)); \ >+ __module_param_call(KBUILD_MODNAME ".", name, ¶m_ops_##type,\ >+ &var, perm, -1, 0) >+ >+/** > * core_param_unsafe - same as core_param but taints kernel > */ > #define core_param_unsafe(name, var, type, perm) \ >-- >2.10.1 >
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