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docs: deprecated.rst: Add uninitialized_var()
Nothing should be using this macro, and the entire idea of tricking the compiler into silencing such warnings is a mistake. Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Cc: Joe Perches <joe@perches.com> Cc: linux-doc@vger.kernel.org Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Kees Cook <keescook@chromium.org>
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@ -51,6 +51,24 @@ to make sure their systems do not continue running in the face of
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"unreachable" conditions. (For example, see commits like `this one
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<https://git.kernel.org/linus/d4689846881d160a4d12a514e991a740bcb5d65a>`_.)
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uninitialized_var()
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-------------------
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For any compiler warnings about uninitialized variables, just add
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an initializer. Using the uninitialized_var() macro (or similar
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warning-silencing tricks) is dangerous as it papers over `real bugs
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<https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/>`_
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(or can in the future), and suppresses unrelated compiler warnings
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(e.g. "unused variable"). If the compiler thinks it is uninitialized,
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either simply initialize the variable or make compiler changes. Keep in
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mind that in most cases, if an initialization is obviously redundant,
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the compiler's dead-store elimination pass will make sure there are no
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needless variable writes.
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As Linus has said, this macro
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`must <https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/>`_
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`be <https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/>`_
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`removed <https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/>`_.
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open-coded arithmetic in allocator arguments
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--------------------------------------------
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Dynamic size calculations (especially multiplication) should not be
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