[ Upstream commit aabdc960a283ba78086b0bf66ee74326f49e218e ] Currently, comparisons to 'm' or 'n' result in incorrect output. [Test Code] config MODULES def_bool y modules config A def_tristate m config B def_bool A > n CONFIG_B is unset, while CONFIG_B=y is expected. The reason for the issue is because Kconfig compares the tristate values as strings. Currently, the .type fields in the constant symbol definitions, symbol_{yes,mod,no} are unspecified, i.e., S_UNKNOWN. When expr_calc_value() evaluates 'A > n', it checks the types of 'A' and 'n' to determine how to compare them. The left-hand side, 'A', is a tristate symbol with a value of 'm', which corresponds to a numeric value of 1. (Internally, 'y', 'm', and 'n' are represented as 2, 1, and 0, respectively.) The right-hand side, 'n', has an unknown type, so it is treated as the string "n" during the comparison. expr_calc_value() compares two values numerically only when both can have numeric values. Otherwise, they are compared as strings. symbol numeric value ASCII code ------------------------------------- y 2 0x79 m 1 0x6d n 0 0x6e 'm' is greater than 'n' if compared numerically (since 1 is greater than 0), but smaller than 'n' if compared as strings (since the ASCII code 0x6d is smaller than 0x6e). Specifying .type=S_TRISTATE for symbol_{yes,mod,no} fixes the above test code. Doing so, however, would cause a regression to the following test code. [Test Code 2] config MODULES def_bool n modules config A def_tristate n config B def_bool A = m You would get CONFIG_B=y, while CONFIG_B should not be set. The reason is because sym_get_string_value() turns 'm' into 'n' when the module feature is disabled. Consequently, expr_calc_value() evaluates 'A = n' instead of 'A = m'. This oddity has been hidden because the type of 'm' was previously S_UNKNOWN instead of S_TRISTATE. sym_get_string_value() should not tweak the string because the tristate value has already been correctly calculated. There is no reason to return the string "n" where its tristate value is mod. Fixes: 31847b67bec0 ("kconfig: allow use of relations other than (in)equality") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>