From: Christoph Hellwig <hch@lst.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, io-uring@vger.kernel.org
Subject: Re: io_uring vs in_compat_syscall()
Date: Tue, 21 Jul 2020 09:07:09 +0200 [thread overview]
Message-ID: <20200721070709.GB11432@lst.de> (raw)
In-Reply-To: <8987E376-6B13-4798-BDBA-616A457447CF@amacapital.net>
On Mon, Jul 20, 2020 at 10:28:55AM -0700, Andy Lutomirski wrote:
> > Sure, I'd consider that implementation detail for the actual patch(es)
> > for this issue.
>
> There’s a corner case, though: doesn’t io_uring submission frequently do the work synchronously in the context of the calling thread?
Yes.
> If so, can a thread do a 64-bit submit with 32-bit work or vice versa?
In theory you could share an fd created in a 32-bit thread to a 64-bit
thread or vice versa, but I think at that point you absolutely are in
"you get to keep the pieces" land.
> Sometimes I think that in_compat_syscall() should have a mode in which calling it warns (e.g. not actually in a syscall when doing things in io_uring). And the relevant operations should be properly wired up to avoid global state like this.
What do you mean with "properly wired up". Do you really want to spread
->compat_foo methods everywhere, including read and write? I found
in_compat_syscall() a lot small and easier to maintain than all the
separate compat cruft.
next prev parent reply other threads:[~2020-07-21 7:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-20 6:10 io_uring vs in_compat_syscall() Christoph Hellwig
2020-07-20 16:36 ` Jens Axboe
2020-07-20 16:58 ` Andy Lutomirski
2020-07-20 17:02 ` Jens Axboe
2020-07-20 17:28 ` Andy Lutomirski
2020-07-21 7:07 ` Christoph Hellwig [this message]
2020-07-21 14:31 ` Andy Lutomirski
2020-07-21 14:34 ` Christoph Hellwig
2020-07-21 17:25 ` Andy Lutomirski
2020-07-22 6:30 ` Christoph Hellwig
2020-07-22 8:39 ` David Laight
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