From: Jeff Moyer <jmoyer@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: "linux-fsdevel\@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-block\@vger.kernel.org" <linux-block@vger.kernel.org>,
linux-aio@kvack.org
Subject: Re: [PATCH] fs: kill unused ret2 argument from iocb->ki_complete()
Date: Wed, 20 Oct 2021 14:37:03 -0400 [thread overview]
Message-ID: <x494k9bo84w.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <16a7a029-0d23-6a14-9ae9-79ab8a9adb34@kernel.dk> (Jens Axboe's message of "Wed, 20 Oct 2021 12:21:55 -0600")
Jens Axboe <axboe@kernel.dk> writes:
> On 10/20/21 12:16 PM, Jeff Moyer wrote:
>> Hi, Jens,
>>
>> Jens Axboe <axboe@kernel.dk> writes:
>>
>>> It's not used for anything, and we're wasting time passing in zeroes
>>> where we could just ignore it instead. Update all ki_complete users in
>>> the kernel to drop that last argument.
>>
>> What does "wasting time passing in zeroes" mean?
>
> That everybody but the funky usb gadget code passes in zero, hence it's
> a waste of time to pass it in as an argument.
OK. Just making sure you hadn't found some performance gain from this.
:)
>> We can't know whether some userspace implementation relies on this
>> behavior, so I don't think you can change it.
>
> Well, I think we should find out, particularly as it's the sole user of
> that extra argument.
How can we find out? Anyone can write userspace usb gadget code. Some
of those users may be proprietary. Is that likely? I don't know. I'd
rather err on the side of not (potentially) breaking existing
applications, though.
> No generic aio code would look at res2, exactly because it is always
> zero for anything but some weird usb gadget code.
I think that no generic code looks at it because it isn't meant to be
interpreted by generic code. :)
-Jeff
next prev parent reply other threads:[~2021-10-20 18:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-20 16:49 [PATCH] fs: kill unused ret2 argument from iocb->ki_complete() Jens Axboe
2021-10-20 17:30 ` Christoph Hellwig
2021-10-20 17:35 ` Jens Axboe
2021-10-20 17:49 ` Greg Kroah-Hartman
2021-10-21 16:40 ` John Keeping
2021-10-21 16:56 ` Jens Axboe
2021-10-22 15:44 ` Jens Axboe
2021-10-23 9:09 ` Greg Kroah-Hartman
2021-10-23 14:01 ` Jens Axboe
2021-10-20 18:16 ` Jeff Moyer
2021-10-20 18:21 ` Jens Axboe
2021-10-20 18:37 ` Jeff Moyer [this message]
2021-10-20 18:41 ` Jens Axboe
2021-10-20 18:56 ` Jens Axboe
2021-10-20 19:11 ` Jeff Moyer
2021-10-20 19:12 ` Jens Axboe
2021-10-20 19:47 ` Jeff Moyer
2021-10-20 19:54 ` Jens Axboe
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