A Kconfig property can have an optional if-expression, which describes
its visibility. The property is visible when the if-expression part is
evaluated to 'y' or 'm'.
The 'select' and 'imply' properties are internally converted to reverse
dependencies, but they are wrongly converted if they have a tristate
if-expression.
Example:
config A
tristate "a"
config B
tristate "b"
select A if C
config C
tristate "c"
Currently, the reverse dependency of 'A' results in 'B && C'.
It is incorrect because the combination of B=y and C=m allows
'A' to become 'm', while its lower limit must be 'y'.
The reverse dependency should be 'B && C != n'.
Randy Dunlap reported that people are trying to fix an individual
Kconfig file [1], and I also found another example in the past,
commit 9d9c98e89ee2 ("pcmcia: fix yenta dependency on PCCARD_NONSTATIC")
but I suspect this is a bug of Kconfig itself.
[1] https://www.spinics.net/lists/netfilter-devel/msg56985.html
Reported-by: Taehee Yoo <ap420073@xxxxxxxxx>
Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
---
scripts/kconfig/menu.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index 4cf15d4..2b18833 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -401,11 +401,13 @@ void menu_finalize(struct menu *parent)
if (prop->type == P_SELECT) {
struct symbol *es = prop_get_symbol(prop);
es->rev_dep.expr = expr_alloc_or(es->rev_dep.expr,
- expr_alloc_and(expr_alloc_symbol(menu->sym), expr_copy(dep)));
+ expr_alloc_and(expr_alloc_symbol(menu->sym),
+ expr_trans_compare(dep, E_UNEQUAL, &symbol_no)));
} else if (prop->type == P_IMPLY) {
struct symbol *es = prop_get_symbol(prop);
es->implied.expr = expr_alloc_or(es->implied.expr,
- expr_alloc_and(expr_alloc_symbol(menu->sym), expr_copy(dep)));
+ expr_alloc_and(expr_alloc_symbol(menu->sym),
+ expr_trans_compare(dep, E_UNEQUAL, &symbol_no)));
}
}
}
--
2.7.4
