4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Masahiro Yamada masahiroy@kernel.org
[ 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@kernel.org Acked-by: Randy Dunlap rdunlap@infradead.org Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/kconfig/expr.c | 29 ----------------------------- scripts/kconfig/expr.h | 1 - scripts/kconfig/menu.c | 2 -- 3 files changed, 32 deletions(-)
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;
/*