netdev - Re: Lots of new warnings with gcc-7.1.1

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Message-ID: <CA+55aFx5mCk+nzDG+gGzDUqE4gzJVERL_oO+PN-PA6oKaUhCpg@mail.gmail.com>
Date:   Tue, 11 Jul 2017 20:41:09 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Tejun Heo <tj@...nel.org>, Jean Delvare <jdelvare@...e.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Sathya Prakash <sathya.prakash@...adcom.com>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        xen-devel <xen-devel@...ts.xenproject.org>,
        linux-block <linux-block@...r.kernel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        IDE-ML <linux-ide@...r.kernel.org>,
        "linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>
Subject: Re: Lots of new warnings with gcc-7.1.1

On Tue, Jul 11, 2017 at 8:17 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> If that's the case, I'd prefer just turning off the format-truncation
> (but not overflow) warning with '-Wno-format-trunction".

Doing

 KBUILD_CFLAGS  += $(call cc-disable-warning, format-truncation)

in the main Makefile certainly cuts down on the warnings.

We still have some overflow warnings, including the crazy one where
gcc doesn't see that the number of max7315 boards is very limited.

But those could easily be converted to just snprintf() instead, and
then the truncation warning disabling takes care of it. Maybe that's
the right answer.

We also have about a bazillion

    warning: ‘*’ in boolean context, suggest ‘&&’ instead

warnings in drivers/ata/libata-core.c, all due to a single macro that
uses a pattern that gcc-7.1.1 doesn't like. The warning looks a bit
debatable, but I suspect the macro could easily be changed too.

Tejun, would you hate just moving the "multiply by 1000" part _into_
that EZ() macro? Something like the attached (UNTESTED!) patch?

              Linus

View attachment "patch.diff" of type "text/plain" (1404 bytes)