linux-kernel - Re: [PATCH] serial: sh-sci: fix uninitialized variable warning

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Date:   Thu, 13 Jun 2019 22:13:07 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Charles <18oliveira.charles@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        rodrigosiqueiramelo@...il.com
Subject: Re: [PATCH] serial: sh-sci: fix uninitialized variable warning

Hi Charles,

On Thu, Jun 13, 2019 at 8:09 PM Charles <18oliveira.charles@...il.com> wrote:
> Avoid following compiler warning on uninitialized variable
>
> In file included from ./include/linux/rwsem.h:16:0,
>                  from ./include/linux/notifier.h:15,
>                  from ./include/linux/clk.h:17,
>                  from drivers/tty/serial/sh-sci.c:24:
> drivers/tty/serial/sh-sci.c: In function ‘sci_dma_rx_submit’:
> ./include/linux/spinlock.h:288:3: warning: ‘flags’ may be used
> uninitialized in this function [-Wmaybe-uninitialized]
>    _raw_spin_unlock_irqrestore(lock, flags); \
>    ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/tty/serial/sh-sci.c:1353:16: note: ‘flags’ was declared here
>   unsigned long flags;
>                 ^~~~~
>
> Signed-off-by: Charles Oliveira <18oliveira.charles@...il.com>

Thanks for your patch, but this is a false positive: the compiler is not
smart enough to realize that both initialization and use depend on
the same condition.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds