On Wed, Aug 25, 2021 at 8:59 PM Péter Ujfalusi [off-list ref] wrote:

Hi,

On 25/08/2021 07:16, Masahiro Yamada wrote:

quoted

Kconfig (syncconfig) generates include/generated/autoconf.h to make
CONFIG options available to the pre-processor.

The macros are suffixed with '_MODULE' for symbols with the value 'm'.

Here is a conflict; CONFIG_FOO=m results in '#define CONFIG_FOO_MODULE 1',
but CONFIG_FOO_MODULE=y also results in the same define.

fixdep always assumes CONFIG_FOO_MODULE comes from CONFIG_FOO=m, so the
dependency is not properly tracked for symbols that end with '_MODULE'.

This commit makes Kconfig error out if it finds a symbol suffixed with
'_MODULE'. This restriction does not exist if the module feature is not
supported (at least from the Kconfig perspective).

It detected one error:
  error: SND_SOC_DM365_VOICE_CODEC_MODULE: symbol name must not end with '_MODULE'

Rename it to SND_SOC_DM365_VOICE_CODEC_MODULAR. Commit 147162f57515
("ASoC: ti: fix SND_SOC_DM365_VOICE_CODEC dependencies") added it for
internal use. So, this renaming has no impact on users.

Remove a comment from drivers/net/wireless/intel/iwlwifi/Kconfig since
this is a hard error now.

Add a comment to include/linux/kconfig.h in order not to worry observant
developers.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 drivers/net/wireless/intel/iwlwifi/Kconfig |  1 -
 include/linux/kconfig.h                    |  3 ++
 scripts/kconfig/parser.y                   | 40 +++++++++++++++++++++-
 sound/soc/ti/Kconfig                       |  2 +-
 4 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/Kconfig b/drivers/net/wireless/intel/iwlwifi/Kconfig
index 1085afbefba8..5b238243617c 100644
--- a/drivers/net/wireless/intel/iwlwifi/Kconfig
+++ b/drivers/net/wireless/intel/iwlwifi/Kconfig

@@ -70,7 +70,6 @@ config IWLMVM
        of the devices that use this firmware is available here:
        https://wireless.wiki.kernel.org/en/users/drivers/iwlwifi#firmware

-# don't call it _MODULE -- will confuse Kconfig/fixdep/...
 config IWLWIFI_OPMODE_MODULAR
      bool
      default y if IWLDVM=m

diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h
index 20d1079e92b4..54f677e742fe 100644
--- a/include/linux/kconfig.h
+++ b/include/linux/kconfig.h

@@ -53,6 +53,9 @@
  * IS_MODULE(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'm', 0
  * otherwise.  CONFIG_FOO=m results in "#define CONFIG_FOO_MODULE 1" in
  * autoconf.h.
+ * CONFIG_FOO_MODULE=y would also result in "#define CONFIG_FOO_MODULE 1",
+ * but Kconfig forbids symbol names that end with '_MODULE', so that would
+ * not happen.
  */
 #define IS_MODULE(option) __is_defined(option##_MODULE)

diff --git a/scripts/kconfig/parser.y b/scripts/kconfig/parser.y
index 2af7ce4e1531..b0f73f74ccd3 100644
--- a/scripts/kconfig/parser.y
+++ b/scripts/kconfig/parser.y

@@ -475,6 +475,37 @@ assign_val:

 %%

+/*
+ * Symbols suffixed with '_MODULE' would cause a macro conflict in autoconf.h,
+ * and also confuse the interaction between syncconfig and fixdep.
+ * Error out if a symbol with the '_MODULE' suffix is found.
+ */
+static int sym_check_name(struct symbol *sym)
+{
+     static const char *suffix = "_MODULE";
+     static const size_t suffix_len = strlen("_MODULE");
+     char *name;
+     size_t len;
+
+     name = sym->name;
+
+     if (!name)
+             return 0;
+
+     len = strlen(name);
+
+     if (len < suffix_len)
+             return 0;
+
+     if (strcmp(name + len - suffix_len, suffix))
+             return 0;
+
+     fprintf(stderr, "error: %s: symbol name must not end with '%s'\n",
+             name, suffix);
+
+     return -1;
+}
+
 void conf_parse(const char *name)
 {
      struct symbol *sym;

@@ -493,8 +524,15 @@ void conf_parse(const char *name)

      if (yynerrs)
              exit(1);
-     if (!modules_sym)
+
+     if (modules_sym) {
+             for_all_symbols(i, sym) {
+                     if (sym_check_name(sym))
+                             yynerrs++;
+             }
+     } else {
              modules_sym = sym_find( "n" );
+     }

      if (!menu_has_prompt(&rootmenu)) {
              current_entry = &rootmenu;

diff --git a/sound/soc/ti/Kconfig b/sound/soc/ti/Kconfig
index 698d7bc84dcf..c56a5789056f 100644
--- a/sound/soc/ti/Kconfig
+++ b/sound/soc/ti/Kconfig

@@ -211,7 +211,7 @@ config SND_SOC_DM365_VOICE_CODEC
        Say Y if you want to add support for SoC On-chip voice codec
 endchoice

-config SND_SOC_DM365_VOICE_CODEC_MODULE
+config SND_SOC_DM365_VOICE_CODEC_MODULAR

This Kconfig option is only used to select the codecs needed for the
voice mode, I think it would be better to use something like

SND_SOC_DM365_SELECT_VOICE_CODECS ?

I do not have a strong opinion.
I am fine with any name unless it ends with _MODULE.


The sound subsystem maintainers and Arnd,
author of 147162f575152db800 are CC'ed.

If they suggest a better name, I'd be happy to adopt it.



-- 
Best Regards
Masahiro Yamada