[PATCH 0/2][next] m68k: amiga: config: Use flexible-array member and mark expected switch fall-through

[PATCH 0/2][next] m68k: amiga: config: Use flexible-array member and mark expected switch fall-through

[Gustavo A. R. Silva]

mark expected switch fall-through
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Cc: linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org

Hi,

This series aims to replace a zero-length array with a flexible-array
member and mark a switch case where we are expecting to fall through.

This also coverts some /* fall through */ comments to the new
pseudo-keyword fallthrough;

Building: allmodconfig m68k

Thanks

Gustavo A. R. Silva (2):
  [next] m68k: amiga: config: Replace zero-length array with
    flexible-array member
  [next] m68k: amiga: config: Mark expected switch fall-through

 arch/m68k/amiga/config.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

-- 
2.26.0

[PATCH 2/2][next] m68k: amiga: config: Mark expected switch fall-through

[Gustavo A. R. Silva]

Mark switch cases where we are expecting to fall through.

This patch fixes the following warning (Building: allmodconfig m68k):

arch/m68k/amiga/config.c: In function ‘amiga_identify’:
./arch/m68k/include/asm/amigahw.h:42:50: warning: this statement may fall through [-Wimplicit-fallthrough=]
 #define AMIGAHW_SET(name) (amiga_hw_present.name = 1)
                           ~~~~~~~~~~~~~~~~~~~~~~~^~~~
arch/m68k/amiga/config.c:223:3: note: in expansion of macro ‘AMIGAHW_SET’
   AMIGAHW_SET(PCMCIA);
   ^~~~~~~~~~~
arch/m68k/amiga/config.c:224:2: note: here
  case AMI_500:
  ^~~~

Replace the existing /* fall through */ comments and fix the issue above
by using the new pseudo-keyword fallthrough;

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 arch/m68k/amiga/config.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/m68k/amiga/config.c b/arch/m68k/amiga/config.c
index 06c15374200e..4eb911d64e8d 100644
--- a/arch/m68k/amiga/config.c
+++ b/arch/m68k/amiga/config.c
@@ -221,6 +221,7 @@ static void __init amiga_identify(void)
 	case AMI_1200:
 		AMIGAHW_SET(A1200_IDE);
 		AMIGAHW_SET(PCMCIA);
+		fallthrough;
 	case AMI_500:
 	case AMI_500PLUS:
 	case AMI_1000:
@@ -233,7 +234,7 @@ static void __init amiga_identify(void)
 	case AMI_3000T:
 		AMIGAHW_SET(AMBER_FF);
 		AMIGAHW_SET(MAGIC_REKICK);
-		/* fall through */
+		fallthrough;
 	case AMI_3000PLUS:
 		AMIGAHW_SET(A3000_SCSI);
 		AMIGAHW_SET(A3000_CLK);
@@ -242,7 +243,7 @@ static void __init amiga_identify(void)
 
 	case AMI_4000T:
 		AMIGAHW_SET(A4000_SCSI);
-		/* fall through */
+		fallthrough;
 	case AMI_4000:
 		AMIGAHW_SET(A4000_IDE);
 		AMIGAHW_SET(A3000_CLK);
-- 
2.26.0

Re: [PATCH 2/2][next] m68k: amiga: config: Mark expected switch fall-through

[Geert Uytterhoeven]

On Fri, Mar 27, 2020 at 12:25 AM Gustavo A. R. Silva
<gustavo@embeddedor.com> wrote:
> Mark switch cases where we are expecting to fall through.
>
> This patch fixes the following warning (Building: allmodconfig m68k):
>
> arch/m68k/amiga/config.c: In function ‘amiga_identify’:
> ./arch/m68k/include/asm/amigahw.h:42:50: warning: this statement may fall through [-Wimplicit-fallthrough=]
>  #define AMIGAHW_SET(name) (amiga_hw_present.name = 1)
>                            ~~~~~~~~~~~~~~~~~~~~~~~^~~~
> arch/m68k/amiga/config.c:223:3: note: in expansion of macro ‘AMIGAHW_SET’
>    AMIGAHW_SET(PCMCIA);
>    ^~~~~~~~~~~
> arch/m68k/amiga/config.c:224:2: note: here
>   case AMI_500:
>   ^~~~
>
> Replace the existing /* fall through */ comments and fix the issue above
> by using the new pseudo-keyword fallthrough;
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
i.e. will queue in the m68k for-v5.8 branch.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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

Re: [PATCH 2/2][next] m68k: amiga: config: Mark expected switch fall-through

[Gustavo A. R. Silva]

On 4/20/20 02:17, Geert Uytterhoeven wrote:
> On Fri, Mar 27, 2020 at 12:25 AM Gustavo A. R. Silva
> <gustavo@embeddedor.com> wrote:
>> Mark switch cases where we are expecting to fall through.
>>
>> This patch fixes the following warning (Building: allmodconfig m68k):
>>
>> arch/m68k/amiga/config.c: In function ‘amiga_identify’:
>> ./arch/m68k/include/asm/amigahw.h:42:50: warning: this statement may fall through [-Wimplicit-fallthrough=]
>>  #define AMIGAHW_SET(name) (amiga_hw_present.name = 1)
>>                            ~~~~~~~~~~~~~~~~~~~~~~~^~~~
>> arch/m68k/amiga/config.c:223:3: note: in expansion of macro ‘AMIGAHW_SET’
>>    AMIGAHW_SET(PCMCIA);
>>    ^~~~~~~~~~~
>> arch/m68k/amiga/config.c:224:2: note: here
>>   case AMI_500:
>>   ^~~~
>>
>> Replace the existing /* fall through */ comments and fix the issue above
>> by using the new pseudo-keyword fallthrough;
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> 
> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
> i.e. will queue in the m68k for-v5.8 branch.
> 

Geert,

I wonder if you received the first patch of the series.

It seems lkml has been eating some messages, recently.

Thanks
--
Gustavo

Re: [PATCH 2/2][next] m68k: amiga: config: Mark expected switch fall-through

[Geert Uytterhoeven]

Hi Gustavo,

On Mon, Apr 20, 2020 at 6:03 PM Gustavo A. R. Silva
<gustavo@embeddedor.com> wrote:
> On 4/20/20 02:17, Geert Uytterhoeven wrote:
> > On Fri, Mar 27, 2020 at 12:25 AM Gustavo A. R. Silva
> > <gustavo@embeddedor.com> wrote:
> >> Mark switch cases where we are expecting to fall through.
> >>
> >> This patch fixes the following warning (Building: allmodconfig m68k):
> >>
> >> arch/m68k/amiga/config.c: In function ‘amiga_identify’:
> >> ./arch/m68k/include/asm/amigahw.h:42:50: warning: this statement may fall through [-Wimplicit-fallthrough=]
> >>  #define AMIGAHW_SET(name) (amiga_hw_present.name = 1)
> >>                            ~~~~~~~~~~~~~~~~~~~~~~~^~~~
> >> arch/m68k/amiga/config.c:223:3: note: in expansion of macro ‘AMIGAHW_SET’
> >>    AMIGAHW_SET(PCMCIA);
> >>    ^~~~~~~~~~~
> >> arch/m68k/amiga/config.c:224:2: note: here
> >>   case AMI_500:
> >>   ^~~~
> >>
> >> Replace the existing /* fall through */ comments and fix the issue above
> >> by using the new pseudo-keyword fallthrough;
> >>
> >> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> >
> > Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
> > i.e. will queue in the m68k for-v5.8 branch.
> >
>
> Geert,
>
> I wonder if you received the first patch of the series.

No I haven't, and lore also only has the cover latter and patch 2/2:
https://lore.kernel.org/linux-m68k/cover.1585264062.git.gustavo@embeddedor.com/

Can you please resend? Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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

[PATCH RESEND 1/2][next] m68k: amiga: config: Replace zero-length array with flexible-array member

[Gustavo A. R. Silva]

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 arch/m68k/amiga/config.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/m68k/amiga/config.c b/arch/m68k/amiga/config.c
index c32ab8041cf6..06c15374200e 100644
--- a/arch/m68k/amiga/config.c
+++ b/arch/m68k/amiga/config.c
@@ -628,7 +628,7 @@ struct savekmsg {
 	unsigned long magic2;		/* SAVEKMSG_MAGIC2 */
 	unsigned long magicptr;		/* address of magic1 */
 	unsigned long size;
-	char data[0];
+	char data[];
 };
 
 static struct savekmsg *savekmsg;
-- 
2.26.0

Re: [PATCH 2/2][next] m68k: amiga: config: Mark expected switch fall-through

[Gustavo A. R. Silva]

On 4/20/20 12:48, Geert Uytterhoeven wrote:

>>
>> I wonder if you received the first patch of the series.
> 
> No I haven't, and lore also only has the cover latter and patch 2/2:
> https://lore.kernel.org/linux-m68k/cover.1585264062.git.gustavo@embeddedor.com/
> 
> Can you please resend? Thanks!
> 

Done. :)
https://lore.kernel.org/linux-m68k/20200420181401.GA32172@embeddedor/

Thanks!
--
Gustavo

Re: [PATCH RESEND 1/2][next] m68k: amiga: config: Replace zero-length array with flexible-array member

[Geert Uytterhoeven]

On Mon, Apr 20, 2020 at 8:09 PM Gustavo A. R. Silva
<gustavo@embeddedor.com> wrote:
> The current codebase makes use of the zero-length array language
> extension to the C90 standard, but the preferred mechanism to declare
> variable-length types such as these ones is a flexible array member[1][2],
> introduced in C99:
>
> struct foo {
>         int stuff;
>         struct boo array[];
> };
>
> By making use of the mechanism above, we will get a compiler warning
> in case the flexible array does not occur last in the structure, which
> will help us prevent some kind of undefined behavior bugs from being
> inadvertently introduced[3] to the codebase from now on.
>
> Also, notice that, dynamic memory allocations won't be affected by
> this change:
>
> "Flexible array members have incomplete type, and so the sizeof operator
> may not be applied. As a quirk of the original implementation of
> zero-length arrays, sizeof evaluates to zero."[1]
>
> This issue was found with the help of Coccinelle.
>
> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> [2] https://github.com/KSPP/linux/issues/21
> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
i.e. will queue in the m68k for-v5.8 branch.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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