linux-kernel - Re: [PATCH] io_uring: fix 1-bit bitfields to be unsigned

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Date:   Thu, 6 Feb 2020 13:42:17 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Randy Dunlap <rdunlap@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>, io-uring@...r.kernel.org
Subject: Re: [PATCH] io_uring: fix 1-bit bitfields to be unsigned

On 2/5/20 9:57 PM, Randy Dunlap wrote:
> From: Randy Dunlap <rdunlap@...radead.org>
> 
> Make bitfields of size 1 bit be unsigned (since there is no room
> for the sign bit).
> This clears up the sparse warnings:
> 
>   CHECK   ../fs/io_uring.c
> ../fs/io_uring.c:207:50: error: dubious one-bit signed bitfield
> ../fs/io_uring.c:208:55: error: dubious one-bit signed bitfield
> ../fs/io_uring.c:209:63: error: dubious one-bit signed bitfield
> ../fs/io_uring.c:210:54: error: dubious one-bit signed bitfield
> ../fs/io_uring.c:211:57: error: dubious one-bit signed bitfield
> 
> Found by sight and then verified with sparse.

Always thought those were pretty silly, it's not like this change is
suddenly going to make:

if (ctx->compat < 0)

be anymore valid (or invalid) than they already are. We also have
cases of:

bool foo:1;

does sparse warn about those?

-- 
Jens Axboe