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From: Jens Axboe <[email protected]>
To: Rasmus Villemoes <[email protected]>,
	Linus Torvalds <[email protected]>
Cc: io-uring <[email protected]>,
	"[email protected]" <[email protected]>
Subject: Re: [GIT PULL] io_uring updates for 5.10-rc1
Date: Tue, 13 Oct 2020 15:00:56 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 10/13/20 2:49 PM, Rasmus Villemoes wrote:
> On 13/10/2020 21.49, Jens Axboe wrote:
>> On 10/13/20 1:46 PM, Linus Torvalds wrote:
>>> On Mon, Oct 12, 2020 at 6:46 AM Jens Axboe <[email protected]> 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.
> 
> Citation needed. There's lots of "pointer to const foo" stuff declared
> as __read_mostly, but I can't find any objects that are themselves both
> const and __read_mostly. Other than that io_op_defs and io_uring_fops now.

You are right, they are all pointers, so not the same. I'll just revert
the patch.

-- 
Jens Axboe


  reply	other threads:[~2020-10-13 21:00 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-12 13:46 [GIT PULL] io_uring updates for 5.10-rc1 Jens Axboe
2020-10-13 19:46 ` Linus Torvalds
2020-10-13 19:49   ` Jens Axboe
2020-10-13 19:50     ` Linus Torvalds
2020-10-13 20:49     ` Rasmus Villemoes
2020-10-13 21:00       ` Jens Axboe [this message]
2020-10-13 21:06     ` Arvind Sankar
2020-10-14 17:43   ` Nick Desaulniers
2020-10-13 19:47 ` pr-tracker-bot

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