Re: [PATCH 5/9] btrfs-progs: Fix Wimplicit-fallthrough warning

From: Nikolay Borisov <nborisov@suse.com>
To: Qu Wenruo <wqu@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 5/9] btrfs-progs: Fix Wimplicit-fallthrough warning
Date: Fri, 16 Nov 2018 10:04:16 +0200	[thread overview]
Message-ID: <f95d5ad5-9be6-ef37-bbbf-189a7059c86b@suse.com> (raw)
In-Reply-To: <20181116075426.4142-6-wqu@suse.com>

On 16.11.18 г. 9:54 ч., Qu Wenruo wrote:
> Although most fallthrough case is pretty obvious, we still need to teach
> the dumb compiler that it's an explicit fallthrough.
> 
> Also reformat the code to use common indent.
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

Is this attribute dependent on a particular compiler version? Does
gcc4.4 for example support it?

> ---
>  utils.c | 30 ++++++++++++++++++++++--------
>  1 file changed, 22 insertions(+), 8 deletions(-)
> 
> diff --git a/utils.c b/utils.c
> index a310300829eb..b274f46fdd9d 100644
> --- a/utils.c
> +++ b/utils.c
> @@ -1134,15 +1134,25 @@ int pretty_size_snprintf(u64 size, char *str, size_t str_size, unsigned unit_mod
>  	num_divs = 0;
>  	last_size = size;
>  	switch (unit_mode & UNITS_MODE_MASK) {
> -	case UNITS_TBYTES: base *= mult; num_divs++;
> -	case UNITS_GBYTES: base *= mult; num_divs++;
> -	case UNITS_MBYTES: base *= mult; num_divs++;
> -	case UNITS_KBYTES: num_divs++;
> -			   break;
> +	case UNITS_TBYTES:
> +		base *= mult;
> +		num_divs++;
> +		__attribute__ ((fallthrough));
> +	case UNITS_GBYTES:
> +		base *= mult;
> +		num_divs++;
> +		__attribute__ ((fallthrough));
> +	case UNITS_MBYTES:
> +		base *= mult;
> +		num_divs++;
> +		__attribute__ ((fallthrough));
> +	case UNITS_KBYTES:
> +		num_divs++;
> +		break;
>  	case UNITS_BYTES:
> -			   base = 1;
> -			   num_divs = 0;
> -			   break;
> +		base = 1;
> +		num_divs = 0;
> +		break;
>  	default:
>  		if (negative) {
>  			s64 ssize = (s64)size;
> @@ -1907,13 +1917,17 @@ int test_num_disk_vs_raid(u64 metadata_profile, u64 data_profile,
>  	default:
>  	case 4:
>  		allowed |= BTRFS_BLOCK_GROUP_RAID10;
> +		__attribute__ ((fallthrough));
>  	case 3:
>  		allowed |= BTRFS_BLOCK_GROUP_RAID6;
> +		__attribute__ ((fallthrough));
>  	case 2:
>  		allowed |= BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
>  			BTRFS_BLOCK_GROUP_RAID5;
> +		__attribute__ ((fallthrough));
>  	case 1:
>  		allowed |= BTRFS_BLOCK_GROUP_DUP;
> +		__attribute__ ((fallthrough));
>  	}
>  
>  	if (dev_cnt > 1 && profile & BTRFS_BLOCK_GROUP_DUP) {
> 