This is a note to let you know that I've just added the patch titled
kconfig: remove wrong expr_trans_bool()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kconfig-remove-wrong-expr_trans_bool.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cff920ddbe5e90b35ba144e3eacbbd24cd29d2f9
Author: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Date: Tue Jun 4 01:19:04 2024 +0900
kconfig: remove wrong expr_trans_bool()
[ Upstream commit 77a92660d8fe8d29503fae768d9f5eb529c88b36 ]
expr_trans_bool() performs an incorrect transformation.
[Test Code]
config MODULES
def_bool y
modules
config A
def_bool y
select C if B != n
config B
def_tristate m
config C
tristate
[Result]
CONFIG_MODULES=y
CONFIG_A=y
CONFIG_B=m
CONFIG_C=m
This output is incorrect because CONFIG_C=y is expected.
Documentation/kbuild/kconfig-language.rst clearly explains the function
of the '!=' operator:
If the values of both symbols are equal, it returns 'n',
otherwise 'y'.
Therefore, the statement:
select C if B != n
should be equivalent to:
select C if y
Or, more simply:
select C
Hence, the symbol C should be selected by the value of A, which is 'y'.
However, expr_trans_bool() wrongly transforms it to:
select C if B
Therefore, the symbol C is selected by (A && B), which is 'm'.
The comment block of expr_trans_bool() correctly explains its intention:
* bool FOO!=n => FOO
^^^^
If FOO is bool, FOO!=n can be simplified into FOO. This is correct.
However, the actual code performs this transformation when FOO is
tristate:
if (e->left.sym->type == S_TRISTATE) {
^^^^^^^^^^
While it can be fixed to S_BOOLEAN, there is no point in doing so
because expr_tranform() already transforms FOO!=n to FOO when FOO is
bool. (see the "case E_UNEQUAL" part)
expr_trans_bool() is wrong and unnecessary.
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index 7e38070ee523b..1c69de8cacf6d 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/expr.c
@@ -395,35 +395,6 @@ static struct expr *expr_eliminate_yn(struct expr *e)
return e;
}
-/*
- * bool FOO!=n => FOO
- */
-struct expr *expr_trans_bool(struct expr *e)
-{
- if (!e)
- return NULL;
- switch (e->type) {
- case E_AND:
- case E_OR:
- case E_NOT:
- e->left.expr = expr_trans_bool(e->left.expr);
- e->right.expr = expr_trans_bool(e->right.expr);
- break;
- case E_UNEQUAL:
- // FOO!=n -> FOO
- if (e->left.sym->type == S_TRISTATE) {
- if (e->right.sym == &symbol_no) {
- e->type = E_SYMBOL;
- e->right.sym = NULL;
- }
- }
- break;
- default:
- ;
- }
- return e;
-}
-
/*
* e1 || e2 -> ?
*/
diff --git a/scripts/kconfig/expr.h b/scripts/kconfig/expr.h
index 43a87f8ea738c..968219750244a 100644
--- a/scripts/kconfig/expr.h
+++ b/scripts/kconfig/expr.h
@@ -302,7 +302,6 @@ struct expr *expr_copy(const struct expr *org);
void expr_free(struct expr *e);
void expr_eliminate_eq(struct expr **ep1, struct expr **ep2);
tristate expr_calc_value(struct expr *e);
-struct expr *expr_trans_bool(struct expr *e);
struct expr *expr_eliminate_dups(struct expr *e);
struct expr *expr_transform(struct expr *e);
int expr_contains_symbol(struct expr *dep, struct symbol *sym);
diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index 4cf15d449c05d..4d48ff3083bd8 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -390,8 +390,6 @@ void menu_finalize(struct menu *parent)
dep = expr_transform(dep);
dep = expr_alloc_and(expr_copy(basedep), dep);
dep = expr_eliminate_dups(dep);
- if (menu->sym && menu->sym->type != S_TRISTATE)
- dep = expr_trans_bool(dep);
prop->visible.expr = dep;
/*
