Re: [PATCH 1/7] xz: add fall-through comments to a switch statement

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 19/11/2021 10:21, Jan Beulich wrote:
> From: Lasse Collin <lasse.collin@xxxxxxxxxxx>
>
> It's good style. I was also told that GCC 7 is more strict and might
> give a warning when such comments are missing.
>
> Suggested-by: Andrei Borzenkov <arvidjaar@xxxxxxxxx>
> Signed-off-by: Lasse Collin <lasse.collin@xxxxxxxxxxx>
> [Linux commit: 5a244f48ecbbd03a11eb84819c5c599db81823ee]
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

> ---
> Linux has meanwhile further moved to using the "fallthrough" pseudo-
> keyword, but us doing so requires the tool stack to first make this
> available for use in at least stubdom builds.
>
> --- a/xen/common/xz/dec_stream.c
> +++ b/xen/common/xz/dec_stream.c
> @@ -583,6 +583,8 @@ static enum xz_ret __init dec_main(struc
>                         if (ret != XZ_OK)
>                                 return ret;
>   
> +		/* Fall through */
> +
>                 case SEQ_BLOCK_START:
>                         /* We need one byte of input to continue. */
>                         if (b->in_pos == b->in_size)
> @@ -606,6 +608,8 @@ static enum xz_ret __init dec_main(struc
>                         s->temp.pos = 0;
>                         s->sequence = SEQ_BLOCK_HEADER;
>   
> +		/* Fall through */
> +
>                 case SEQ_BLOCK_HEADER:
>                         if (!fill_temp(s, b))
>                                 return XZ_OK;
> @@ -616,6 +620,8 @@ static enum xz_ret __init dec_main(struc
>   
>   			s->sequence = SEQ_BLOCK_UNCOMPRESS;
>   
> +		/* Fall through */
> +
>                 case SEQ_BLOCK_UNCOMPRESS:
>                         ret = dec_block(s, b);
>                         if (ret != XZ_STREAM_END)
> @@ -623,6 +629,8 @@ static enum xz_ret __init dec_main(struc
>   
>   			s->sequence = SEQ_BLOCK_PADDING;
>   
> +		/* Fall through */
> +
>                 case SEQ_BLOCK_PADDING:
>                         /*
>                          * Size of Compressed Data + Block Padding
> @@ -643,6 +651,8 @@ static enum xz_ret __init dec_main(struc
>   
>   			s->sequence = SEQ_BLOCK_CHECK;
>   
> +		/* Fall through */
> +
>                 case SEQ_BLOCK_CHECK:
>                         if (s->check_type == XZ_CHECK_CRC32) {
>                                 ret = crc32_validate(s, b);
> @@ -665,6 +675,8 @@ static enum xz_ret __init dec_main(struc
>   
>   			s->sequence = SEQ_INDEX_PADDING;
>   
> +		/* Fall through */
> +
>                 case SEQ_INDEX_PADDING:
>                         while ((s->index.size + (b->in_pos - s->in_start))
>                                         & 3) {
> @@ -687,6 +699,8 @@ static enum xz_ret __init dec_main(struc
>   
>   			s->sequence = SEQ_INDEX_CRC32;
>   
> +		/* Fall through */
> +
>                 case SEQ_INDEX_CRC32:
>                         ret = crc32_validate(s, b);
>                         if (ret != XZ_STREAM_END)
> @@ -695,6 +709,8 @@ static enum xz_ret __init dec_main(struc
>                         s->temp.size = STREAM_HEADER_SIZE;
>                         s->sequence = SEQ_STREAM_FOOTER;
>   
> +		/* Fall through */
> +
>                 case SEQ_STREAM_FOOTER:
>                         if (!fill_temp(s, b))
>                                 return XZ_OK;
--
Julien Grall