Lots of new warnings with gcc-7.1.1

Commit Message

Linus Torvalds July 12, 2017, 3:41 a.m. UTC

On Tue, Jul 11, 2017 at 8:17 PM, Linus Torvalds
<[e-mail]> 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
drivers/ata/libata-core.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

Comments

Arnd Bergmann July 12, 2017, 1:31 p.m. UTC | #1

On Wed, Jul 12, 2017 at 5:41 AM, Linus Torvalds
<[e-mail]> wrote:

>
> 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?

Tejun applied an almost identical patch of mine a while ago, but it seems to
have gotten lost in the meantime in some rebase:

https://patchwork.kernel.org/patch/9721397/
https://patchwork.kernel.org/patch/9721399/

I guess I should have resubmitted the second patch with the suggested
improvement.

     Arnd

Tejun Heo July 15, 2017, 11:03 a.m. UTC | #2

Hello,

On Wed, Jul 12, 2017 at 03:31:02PM +0200, Arnd Bergmann wrote:
> > 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?
> 
> Tejun applied an almost identical patch of mine a while ago, but it seems to
> have gotten lost in the meantime in some rebase:

Yeah, I was scratching my head remembering your patch.  Sorry about
that.  It should have been routed through for-4.12-fixes.

> https://patchwork.kernel.org/patch/9721397/
> https://patchwork.kernel.org/patch/9721399/
> 
> I guess I should have resubmitted the second patch with the suggested
> improvement.

The new one looks good to me.

Thanks.

Patch

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 8453f9a4682f..4c7d5a138495 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -3231,19 +3231,19 @@  static const struct ata_timing ata_timing[] = {
 };
 
 #define ENOUGH(v, unit)		(((v)-1)/(unit)+1)
-#define EZ(v, unit)		((v)?ENOUGH(v, unit):0)
+#define EZ(v, unit)		((v)?ENOUGH((v)*1000, unit):0)
 
 static void ata_timing_quantize(const struct ata_timing *t, struct ata_timing *q, int T, int UT)
 {
-	q->setup	= EZ(t->setup      * 1000,  T);
-	q->act8b	= EZ(t->act8b      * 1000,  T);
-	q->rec8b	= EZ(t->rec8b      * 1000,  T);
-	q->cyc8b	= EZ(t->cyc8b      * 1000,  T);
-	q->active	= EZ(t->active     * 1000,  T);
-	q->recover	= EZ(t->recover    * 1000,  T);
-	q->dmack_hold	= EZ(t->dmack_hold * 1000,  T);
-	q->cycle	= EZ(t->cycle      * 1000,  T);
-	q->udma		= EZ(t->udma       * 1000, UT);
+	q->setup	= EZ(t->setup,      T);
+	q->act8b	= EZ(t->act8b,      T);
+	q->rec8b	= EZ(t->rec8b,      T);
+	q->cyc8b	= EZ(t->cyc8b,      T);
+	q->active	= EZ(t->active,     T);
+	q->recover	= EZ(t->recover,    T);
+	q->dmack_hold	= EZ(t->dmack_hold, T);
+	q->cycle	= EZ(t->cycle,      T);
+	q->udma		= EZ(t->udma,       UT);
 }
 
 void ata_timing_merge(const struct ata_timing *a, const struct ata_timing *b,