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From:   Arnd Bergmann <arnd@kernel.org>
Date:   Mon, 26 Oct 2020 20:07:39 +0100
Message-ID: <CAK8P3a1ASxy3w62A16Ne9AkM2kfF5ZokYOfos53FSTQdkXha4Q@mail.gmail.com>
Subject: Re: [PATCH] seq_buf: avoid type mismatch for seq_buf_init
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Ingo Molnar <mingo@redhat.com>, Jiri Kosina <jkosina@suse.cz>,
        Petr Mladek <pmladek@suse.cz>,
        Piotr Maziarz <piotrx.maziarz@linux.intel.com>,
        Cezary Rojewski <cezary.rojewski@intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Mon, Oct 26, 2020 at 6:23 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Mon, 26 Oct 2020 17:10:58 +0100
> Arnd Bergmann <arnd@kernel.org> wrote:
>
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > Building with W=2 prints a number of warnings for one function that
> > has a pointer type mismatch:
> >
> > linux/seq_buf.h: In function 'seq_buf_init':
> > linux/seq_buf.h:35:12: warning: pointer targets in assignment from 'unsigned char *' to 'char *' differ in signedness [-Wpointer-sign]
>
> I've always hated the warning about char * and unsigned char *, as they are
> mostly meaningless. Yes, bugs happen with int to unsigned int conversions,
> but this is dealing with strings, where unsigned char * and char * are
> basically equivalent, except when it comes to one thing, which is why I
> prefer unsigned char * over char *, and that is printing out the numerical
> values of a buffer, if they go above 177, the char * prints the negative
> value, but unsigned char * keeps printing what you would expect.

I agree it's a super annoying warning, which is exactly why I sent the
fixes to shut it up in common headers. At least that way, building a specific
driver with W=2 will only show the warnings in that driver, rather than
those in header files as well.

> As this is just an annoyance (extra warnings), and not really a "fix", I'll
> queue it up for the next merge window.

Yes, that was the idea, thanks!

        Arnd