Re: [PATCH] kconfig: Avoid prompting for transitional symbols

[Vegard Nossum]

On 30/09/2025 06:53, Kees Cook wrote:

The "transitional" symbol keyword, while working with the "olddefconfig"
target, was prompting during "oldconfig". This occurred because these
symbols were not being marked as user-defined when they received values
from transitional symbols that had user values. The "olddefconfig" target
explicitly doesn't prompt for anything, so this deficiency wasn't noticed.

The issue manifested when a symbol's value came from a transitional
symbol's user value but the receiving symbol wasn't marked with
SYMBOL_DEF_USER. Thus the "oldconfig" logic would then prompt for these
symbols unnecessarily.

Check after value calculation whether a symbol without a user value
gets its value from a single transitional symbol that does have a user
value. In such cases, mark the receiving symbol as user-defined to
prevent prompting.

Sorry for not catching this issue.

diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
index 760cac998381..9cc2fd5bc016 100644
--- a/scripts/kconfig/symbol.c
+++ b/scripts/kconfig/symbol.c
@@ -411,7 +411,7 @@ bool sym_dep_errors(void)
  void sym_calc_value(struct symbol *sym)
  {
        struct symbol_value newval, oldval;
-       struct property *prop;
+       struct property *prop = NULL;
        struct menu *choice_menu;

if (!sym)

@@ -520,6 +520,22 @@ void sym_calc_value(struct symbol *sym)
                ;
        }

+ /*

+        * If the symbol lacks a user value but its value comes from a
+        * single transitional symbol with an existing user value, mark
+        * this symbol as having a user value to avoid prompting.
+        */
+       if (prop && !sym_has_value(sym)) {
+               struct symbol *ds = prop_get_symbol(prop);
+               if (ds && (ds->flags & SYMBOL_TRANS) && sym_has_value(ds)) {
+                       if (sym->type == S_BOOLEAN || sym->type == S_TRISTATE)
+                               sym->def[S_DEF_USER].tri = newval.tri;
+                       else
+                               sym->def[S_DEF_USER].val = newval.val;

sym->def[S_DEF_USER] and newval are both 'struct symbol_value', can we
just unconditionally do this instead?

    sym->def[S_DEF_USER] = newval;

+                       sym->flags |= SYMBOL_DEF_USER;
+               }
+       }
+
        sym->curr = newval;
        sym_validate_range(sym);

I have to run, will take a closer look later. Thanks,


Vegard