Nothing should be using this macro, and the entire idea of tricking the compiler into silencing such warnings is a mistake. Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- Documentation/process/deprecated.rst | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst index 652e2aa02a66..943a926ecbbb 100644 --- a/Documentation/process/deprecated.rst +++ b/Documentation/process/deprecated.rst @@ -51,6 +51,24 @@ to make sure their systems do not continue running in the face of "unreachable" conditions. (For example, see commits like `this one <https://git.kernel.org/linus/d4689846881d160a4d12a514e991a740bcb5d65a>`_.) +uninitialized_var() +------------------- +For any compiler warnings about uninitialized variables, just add +an initializer. Using the uninitialized_var() macro (or similar +warning-silencing tricks) is dangerous as it papers over `real bugs +<https://lore.kernel.org/lkml/20200603174714.192027-1-glider@xxxxxxxxxx/>`_ +(or can in the future), and suppresses unrelated compiler warnings +(e.g. "unused variable"). If the compiler thinks it is uninitialized, +either simply initialize the variable or make compiler changes. Keep in +mind that in most cases, if an initialization is obviously redundant, +the compiler's dead-store elimination pass will make sure there are no +needless variable writes. + +As Linus has said, this macro +`must <https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@xxxxxxxxxxxxxx/>`_ +`be <https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@xxxxxxxxxxxxxx/>`_ +`removed <https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@xxxxxxxxxxxxxx/>`_. + open-coded arithmetic in allocator arguments -------------------------------------------- Dynamic size calculations (especially multiplication) should not be -- 2.25.1
