linux-kernel - -Wsometimes-uninitialized Clang warning in drivers/tty/serial/qcom_geni

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Date:   Thu, 7 Mar 2019 17:45:26 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Karthikeyan Ramasubramanian <kramasub@...eaurora.org>,
        Douglas Anderson <dianders@...omium.org>,
        Ryan Case <ryandcase@...omium.org>
Cc:     linux-arm-msm@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux@...glegroups.com
Subject: -Wsometimes-uninitialized Clang warning in
 drivers/tty/serial/qcom_geni_serial.c

Hi all,

We are trying to get Clang's -Wsometimes-uninitialized turned on for the
kernel as it can catch some bugs that GCC can't. This warning came up:

drivers/tty/serial/qcom_geni_serial.c:1079:6: warning: variable 'baud' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
        if (options)
            ^~~~~~~
drivers/tty/serial/qcom_geni_serial.c:1082:37: note: uninitialized use occurs here
        return uart_set_options(uport, co, baud, parity, bits, flow);
                                           ^~~~
drivers/tty/serial/qcom_geni_serial.c:1079:2: note: remove the 'if' if its condition is always true
        if (options)
        ^~~~~~~~~~~~
drivers/tty/serial/qcom_geni_serial.c:1053:10: note: initialize the variable 'baud' to silence this warning
        int baud;
                ^
                 = 0
1 warning generated.

While this is probably not an issue in practice (I assume baud is always
supplied as an option), we should clean up this warning. I would fix it
myself but I have no idea what baud's initial value should be as it
seems it is dependent on the driver. Your input would be much
appreciated.

Cheers,
Nathan