linux-kernel - Re: [GIT PULL] io_uring updates for 5.10-rc1

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Message-ID: <a81737e4-44da-cffc-cba0-8aec984df240@kernel.dk>
Date:   Tue, 13 Oct 2020 13:49:01 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     io-uring <io-uring@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] io_uring updates for 5.10-rc1

On 10/13/20 1:46 PM, Linus Torvalds wrote:
> On Mon, Oct 12, 2020 at 6:46 AM Jens Axboe <axboe@...nel.dk> wrote:
>>
>> Here are the io_uring updates for 5.10.
> 
> Very strange. My clang build gives a warning I've never seen before:
> 
>    /tmp/io_uring-dd40c4.s:26476: Warning: ignoring changed section
> attributes for .data..read_mostly
> 
> and looking at what clang generates for the *.s file, it seems to be
> the "section" line in:
> 
>         .type   io_op_defs,@object      # @io_op_defs
>         .section        .data..read_mostly,"a",@progbits
>         .p2align        4
> 
> I think it's the combination of "const" and "__read_mostly".
> 
> I think the warning is sensible: how can a piece of data be both
> "const" and "__read_mostly"? If it's "const", then it's not "mostly"
> read - it had better be _always_ read.
> 
> I'm letting it go, and I've pulled this (gcc doesn't complain), but
> please have a look.

Huh weird, I'll take a look. FWIW, the construct isn't unique across
the kernel.

What clang are you using?

-- 
Jens Axboe