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From: Matthew Wilcox <willy@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Stefano Garzarella <sgarzare@redhat.com>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Kees Cook <keescook@chromium.org>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	strace-devel@lists.strace.io, io-uring@vger.kernel.org,
	Pavel Begunkov <asml.silence@gmail.com>,
	Linux API <linux-api@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: strace of io_uring events?
Date: Wed, 15 Jul 2020 18:11:30 +0100	[thread overview]
Message-ID: <20200715171130.GG12769@casper.infradead.org> (raw)
In-Reply-To: <D9FAB37B-D059-4137-A115-616237D78640@amacapital.net>

On Wed, Jul 15, 2020 at 07:35:50AM -0700, Andy Lutomirski wrote:
> > On Jul 15, 2020, at 4:12 AM, Miklos Szeredi <miklos@szeredi.hu> wrote:
> > 
> > <feff>Hi,

feff?  Are we doing WTF-16 in email now?  ;-)

> > 
> > This thread is to discuss the possibility of stracing requests
> > submitted through io_uring.   I'm not directly involved in io_uring
> > development, so I'm posting this out of  interest in using strace on
> > processes utilizing io_uring.
> > 
> > io_uring gives the developer a way to bypass the syscall interface,
> > which results in loss of information when tracing.  This is a strace
> > fragment on  "io_uring-cp" from liburing:
> > 
> > io_uring_enter(5, 40, 0, 0, NULL, 8)    = 40
> > io_uring_enter(5, 1, 0, 0, NULL, 8)     = 1
> > io_uring_enter(5, 1, 0, 0, NULL, 8)     = 1
> > ...
> > 
> > What really happens are read + write requests.  Without that
> > information the strace output is mostly useless.
> > 
> > This loss of information is not new, e.g. calls through the vdso or
> > futext fast paths are also invisible to strace.  But losing filesystem
> > I/O calls are a major blow, imo.
> > 
> > What do people think?
> > 
> > From what I can tell, listing the submitted requests on
> > io_uring_enter() would not be hard.  Request completion is
> > asynchronous, however, and may not require  io_uring_enter() syscall.
> > Am I correct?
> > 
> > Is there some existing tracing infrastructure that strace could use to
> > get async completion events?  Should we be introducing one?
> > 
> > 
> 
> Let’s add some seccomp folks. We probably also want to be able to run seccomp-like filters on io_uring requests. So maybe io_uring should call into seccomp-and-tracing code for each action.

Adding Stefano since he had a complementary proposal for iouring
restrictions that weren't exactly seccomp.

  reply	other threads:[~2020-07-15 17:11 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-15 11:12 Miklos Szeredi
2020-07-15 14:35 ` Andy Lutomirski
2020-07-15 17:11   ` Matthew Wilcox [this message]
2020-07-15 19:42     ` Pavel Begunkov
2020-07-15 20:09       ` Miklos Szeredi
2020-07-15 20:20         ` Pavel Begunkov
2020-07-15 23:07           ` Kees Cook
2020-07-16 13:14             ` Stefano Garzarella
2020-07-16 15:12               ` Kees Cook
2020-07-17  8:01                 ` Stefano Garzarella
2020-07-21 15:27                   ` Andy Lutomirski
2020-07-21 15:31                     ` Jens Axboe
2020-07-21 17:23                       ` Andy Lutomirski
2020-07-21 17:30                         ` Jens Axboe
2020-07-21 17:44                           ` Andy Lutomirski
2020-07-21 18:39                             ` Jens Axboe
2020-07-21 19:44                               ` Andy Lutomirski
2020-07-21 19:48                                 ` Jens Axboe
2020-07-21 19:56                                 ` Andres Freund
2020-07-21 19:37                         ` Andres Freund
2020-07-21 15:58                     ` Stefano Garzarella
2020-07-23 10:39                       ` Stefan Hajnoczi
2020-07-23 13:37                       ` Colin Walters
2020-07-24  7:25                         ` Stefano Garzarella
2020-07-16 13:17             ` Aleksa Sarai
2020-07-16 15:19               ` Kees Cook
2020-07-17  8:17               ` Cyril Hrubis
2020-07-16 16:24             ` Andy Lutomirski
2020-07-16  0:12     ` tytso

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