Re: [PATCH v3] lib/siphash.c: annotate implicit fall throughs

[Jason A. Donenfeld]

Hi Mathieu,

Thanks for getting this v3 into shape.

On Wed, Mar 13, 2019 at 3:12 PM Mathieu Malaterre <malat@xxxxxxxxxx> wrote:
> There is a plan to build the kernel with -Wimplicit-fallthrough and
> these places in the code produced warnings (W=1). Fix them up.
>
> This commit remove the following warnings:
>
>   lib/siphash.c:71:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>   lib/siphash.c:72:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>   lib/siphash.c:73:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>   lib/siphash.c:75:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>   lib/siphash.c:108:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>   lib/siphash.c:109:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>   lib/siphash.c:110:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>   lib/siphash.c:112:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>   lib/siphash.c:434:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>   lib/siphash.c:462:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>
> Move the break statement onto the next line to match the fall-through
> comment pattern. Also move the trailing statement onto the next line to
> pass checkpatch verification.
>
> Acked-by: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx>
> Signed-off-by: Mathieu Malaterre <malat@xxxxxxxxxx>
> ---
> v3: move break statements onto next line and please checkpatch
> v2: some cases were missed in v1, update missing ones
>
>  lib/siphash.c | 76 +++++++++++++++++++++++++++++++++++++--------------
>  1 file changed, 56 insertions(+), 20 deletions(-)
>
> diff --git a/lib/siphash.c b/lib/siphash.c
> index 3ae58b4edad6..f459e0f4a14e 100644
> --- a/lib/siphash.c
> +++ b/lib/siphash.c
> @@ -68,13 +68,26 @@ u64 __siphash_aligned(const void *data, size_t len, const siphash_key_t *key)
>                                                   bytemask_from_count(left)));
>  #else
>         switch (left) {
> -       case 7: b |= ((u64)end[6]) << 48;
> -       case 6: b |= ((u64)end[5]) << 40;
> -       case 5: b |= ((u64)end[4]) << 32;
> -       case 4: b |= le32_to_cpup(data); break;
> -       case 3: b |= ((u64)end[2]) << 16;
> -       case 2: b |= le16_to_cpup(data); break;
> -       case 1: b |= end[0];
> +       case 7:
> +               b |= ((u64)end[6]) << 48;
> +               /* fall through */
> +       case 6:
> +               b |= ((u64)end[5]) << 40;
> +               /* fall through */
> +       case 5:
> +               b |= ((u64)end[4]) << 32;
> +               /* fall through */
> +       case 4:
> +               b |= le32_to_cpup(data);
> +               break;
> +       case 3:
> +               b |= ((u64)end[2]) << 16;
> +               /* fall through */
> +       case 2:
> +               b |= le16_to_cpup(data);
> +               break;
> +       case 1:
> +               b |= end[0];
>         }
>  #endif
>         POSTAMBLE
> @@ -101,13 +114,26 @@ u64 __siphash_unaligned(const void *data, size_t len, const siphash_key_t *key)
>                                                   bytemask_from_count(left)));
>  #else
>         switch (left) {
> -       case 7: b |= ((u64)end[6]) << 48;
> -       case 6: b |= ((u64)end[5]) << 40;
> -       case 5: b |= ((u64)end[4]) << 32;
> -       case 4: b |= get_unaligned_le32(end); break;
> -       case 3: b |= ((u64)end[2]) << 16;
> -       case 2: b |= get_unaligned_le16(end); break;
> -       case 1: b |= end[0];
> +       case 7:
> +               b |= ((u64)end[6]) << 48;
> +               /* fall through */
> +       case 6:
> +               b |= ((u64)end[5]) << 40;
> +               /* fall through */
> +       case 5:
> +               b |= ((u64)end[4]) << 32;
> +               /* fall through */
> +       case 4:
> +               b |= get_unaligned_le32(end);
> +               break;
> +       case 3:
> +               b |= ((u64)end[2]) << 16;
> +               /* fall through */
> +       case 2:
> +               b |= get_unaligned_le16(end);
> +               break;
> +       case 1:
> +               b |= end[0];
>         }
>  #endif
>         POSTAMBLE
> @@ -431,9 +457,14 @@ u32 __hsiphash_aligned(const void *data, size_t len, const hsiphash_key_t *key)
>                 v0 ^= m;
>         }
>         switch (left) {
> -       case 3: b |= ((u32)end[2]) << 16;
> -       case 2: b |= le16_to_cpup(data); break;
> -       case 1: b |= end[0];
> +       case 3:
> +               b |= ((u32)end[2]) << 16;
> +               /* fall through */
> +       case 2:
> +               b |= le16_to_cpup(data);
> +               break;
> +       case 1:
> +               b |= end[0];
>         }
>         HPOSTAMBLE
>  }
> @@ -454,9 +485,14 @@ u32 __hsiphash_unaligned(const void *data, size_t len,
>                 v0 ^= m;
>         }
>         switch (left) {
> -       case 3: b |= ((u32)end[2]) << 16;
> -       case 2: b |= get_unaligned_le16(end); break;
> -       case 1: b |= end[0];
> +       case 3:
> +               b |= ((u32)end[2]) << 16;
> +               /* fall through */
> +       case 2:
> +               b |= get_unaligned_le16(end);
> +               break;
> +       case 1:
> +               b |= end[0];
>         }
>         HPOSTAMBLE
>  }
> --
> 2.20.1

Reviewed-by: Jason A. Donenfeld <Jason@xxxxxxxxx>

Greg - would you take this through your tree?

Jason