linux-block.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Arnd Bergmann <arnd@arndb.de>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>,
	Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
	linux-aio <linux-aio@kvack.org>,
	linux-block <linux-block@vger.kernel.org>,
	Jeff Moyer <jmoyer@redhat.com>, Avi Kivity <avi@scylladb.com>,
	Linux API <linux-api@vger.kernel.org>,
	linux-man@vger.kernel.org,
	Deepa Dinamani <deepa.kernel@gmail.com>
Subject: Re: [PATCH 05/18] Add io_uring IO interface
Date: Tue, 29 Jan 2019 12:58:37 +0100	[thread overview]
Message-ID: <CAK8P3a1x4BsFfacxOmaDXKOKmmQ2j0ypX2+mCNCbjH3E7nC4DQ@mail.gmail.com> (raw)
In-Reply-To: <20190129063043.GC2996@lst.de>

On Tue, Jan 29, 2019 at 7:30 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Mon, Jan 28, 2019 at 11:25:12AM -0700, Jens Axboe wrote:
> > > Especially with poll support now in the series, don't we need a ѕigmask
> > > argument similar to pselect/ppoll/io_pgetevents now to deal with signal
> > > blocking during waiting for events?
> >
> > Is there any way to avoid passing in the sigset_t size? If it's just a
> > 32-bit/64-bit thing, surely the in_compat_syscall() could cover it? Or
> > are there other cases that need to be catered to?
>
> As far as I can tell we never look at it, never looked at it and don't
> have any plans to look at it anytime soon.  But when I tried to omit
> it for io_pgetevents I got stong pushback and thus had to add the
> crazy double indirection calling convention.

Deepa has recently reworked the handling for the sigset_t handling
to be more consistent. As I understand it, we only ever check the
size argument to ensure that user and kernel space agree on
the size, as it there had been some historic differences.

If you pass a signal mask to a syscall, you should now just use the
set_user_sigmask()/set_compat_user_sigmask()/restore_user_sigmask()
helpers. The compat version is required for the incompatible bit order
between 32-bit and 64-bit big-endian architectures (on little-endian, compat
and native signal masks are compatible), and to deal with the one
architecture that has an _NSIG defined to something other than 64:
MIPS uses 128 because of a historic accident.

I think Deepa originally suggested combining set_user_sigmask()
and set_compat_user_sigmask(), using an in_compat_syscall()
check. This would let us simplify a number of compat syscalls
(ppoll, ppoll_time32, pselect6, pselect6_time32, epoll_pwait()
io_pgetevents_time64, io_pgetevents_time32). I advised against
changing it at the time for consistency with other compat syscalls,
but it's something we can still do now.

There was a recent discussion about the size of sigset_t in glibc,
which is 1024 bits there instead of 64 bits in the kernel, the idea
being that the kernel might eventually grow more signals at
some point in the future, as we did when we extended from 32
to 64 a long time ago with the addition of the rt_sig* signals;
see the thread around
https://www.spinics.net/lists/linux-snps-arc/msg04860.html

    Arnd

  reply	other threads:[~2019-01-29 11:59 UTC|newest]

Thread overview: 109+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-23 15:35 [PATCHSET v7] io_uring IO interface Jens Axboe
2019-01-23 15:35 ` [PATCH 01/18] fs: add an iopoll method to struct file_operations Jens Axboe
2019-01-28 14:25   ` Christoph Hellwig
2019-01-28 16:13     ` Jens Axboe
2019-01-23 15:35 ` [PATCH 02/18] block: wire up block device iopoll method Jens Axboe
2019-01-23 15:35 ` [PATCH 03/18] block: add bio_set_polled() helper Jens Axboe
2019-01-28 14:26   ` Christoph Hellwig
2019-01-23 15:35 ` [PATCH 04/18] iomap: wire up the iopoll method Jens Axboe
2019-01-23 15:35 ` [PATCH 05/18] Add io_uring IO interface Jens Axboe
2019-01-28 14:57   ` Christoph Hellwig
2019-01-28 16:26     ` Jens Axboe
2019-01-28 16:34       ` Christoph Hellwig
2019-01-28 19:32         ` Jens Axboe
2019-01-28 18:25     ` Jens Axboe
2019-01-29  6:30       ` Christoph Hellwig
2019-01-29 11:58         ` Arnd Bergmann [this message]
2019-01-29 15:20           ` Jens Axboe
2019-01-29 16:18             ` Arnd Bergmann
2019-01-29 16:19               ` Jens Axboe
2019-01-29 16:26                 ` Arnd Bergmann
2019-01-29 16:28                   ` Jens Axboe
2019-01-29 16:46                     ` Arnd Bergmann
2019-01-29  0:47     ` Andy Lutomirski
2019-01-29  1:20       ` Jens Axboe
2019-01-29  6:45         ` Christoph Hellwig
2019-01-29 12:05           ` Arnd Bergmann
2019-01-31  5:11         ` Andy Lutomirski
2019-01-31 16:37           ` Jens Axboe
2019-01-23 15:35 ` [PATCH 06/18] io_uring: add fsync support Jens Axboe
2019-01-23 15:35 ` [PATCH 07/13] io_uring: add support for pre-mapped user IO buffers Jens Axboe
2019-01-23 15:35 ` [PATCH 07/18] io_uring: support for IO polling Jens Axboe
2019-01-28 15:02   ` Christoph Hellwig
2019-01-28 16:46     ` Jens Axboe
2019-01-29  6:27       ` Christoph Hellwig
2019-01-29 13:20         ` Jens Axboe
2019-01-23 15:35 ` [PATCH 08/18] fs: add fget_many() and fput_many() Jens Axboe
2019-01-28 14:29   ` Christoph Hellwig
2019-01-28 16:48     ` Jens Axboe
2019-01-23 15:35 ` [PATCH 08/13] io_uring: add file set registration Jens Axboe
2019-01-23 15:35 ` [PATCH 09/13] io_uring: add submission polling Jens Axboe
2019-01-28 15:09   ` Christoph Hellwig
2019-01-28 17:05     ` Jens Axboe
2019-01-29  6:29       ` Christoph Hellwig
2019-01-29 13:21         ` Jens Axboe
2019-01-28 21:13   ` Jeff Moyer
2019-01-28 21:28     ` Jens Axboe
2019-01-23 15:35 ` [PATCH 09/18] io_uring: use fget/fput_many() for file references Jens Axboe
2019-01-23 15:35 ` [PATCH 10/13] io_uring: add io_kiocb ref count Jens Axboe
2019-01-23 15:35 ` [PATCH 10/18] io_uring: batch io_kiocb allocation Jens Axboe
2019-01-23 15:35 ` [PATCH 11/18] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2019-01-28 14:31   ` Christoph Hellwig
2019-01-28 16:54     ` Jens Axboe
2019-01-23 15:35 ` [PATCH 11/13] io_uring: add support for IORING_OP_POLL Jens Axboe
2019-01-23 15:35 ` [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers Jens Axboe
2019-01-23 15:35 ` [PATCH 12/13] io_uring: allow workqueue item to handle multiple buffered requests Jens Axboe
2019-01-23 15:35 ` [PATCH 13/18] io_uring: add file set registration Jens Axboe
2019-01-23 15:35 ` [PATCH 13/13] io_uring: add io_uring_event cache hit information Jens Axboe
2019-01-23 15:35 ` [PATCH 14/18] io_uring: add submission polling Jens Axboe
2019-01-23 15:35 ` [PATCH 15/18] io_uring: add io_kiocb ref count Jens Axboe
2019-01-23 15:35 ` [PATCH 16/18] io_uring: add support for IORING_OP_POLL Jens Axboe
2019-01-23 15:35 ` [PATCH 17/18] io_uring: allow workqueue item to handle multiple buffered requests Jens Axboe
2019-01-23 15:35 ` [PATCH 18/18] io_uring: add io_uring_event cache hit information Jens Axboe
2019-01-28 21:35 [PATCHSET v8] io_uring IO interface Jens Axboe
2019-01-28 21:35 ` [PATCH 05/18] Add " Jens Axboe
2019-01-28 21:53   ` Jeff Moyer
2019-01-28 21:56     ` Jens Axboe
2019-01-28 22:32   ` Jann Horn
2019-01-28 23:46     ` Jens Axboe
2019-01-28 23:59       ` Jann Horn
2019-01-29  0:03         ` Jens Axboe
2019-01-29  0:31           ` Jens Axboe
2019-01-29  0:34             ` Jann Horn
2019-01-29  0:55               ` Jens Axboe
2019-01-29  0:58                 ` Jann Horn
2019-01-29  1:01                   ` Jens Axboe
2019-02-01 16:57         ` Matt Mullins
2019-02-01 17:04           ` Jann Horn
2019-02-01 17:23             ` Jann Horn
2019-02-01 18:05               ` Al Viro
2019-01-29  1:07   ` Jann Horn
2019-01-29  2:21     ` Jann Horn
2019-01-29  2:54       ` Jens Axboe
2019-01-29  3:46       ` Jens Axboe
2019-01-29 15:56         ` Jann Horn
2019-01-29 16:06           ` Jens Axboe
2019-01-29  2:21     ` Jens Axboe
2019-01-29  1:29   ` Jann Horn
2019-01-29  1:31     ` Jens Axboe
2019-01-29  1:32       ` Jann Horn
2019-01-29  2:23         ` Jens Axboe
2019-01-29  7:12   ` Bert Wesarg
2019-01-29 12:12   ` Florian Weimer
2019-01-29 13:35     ` Jens Axboe
2019-01-29 15:38       ` Jann Horn
2019-01-29 15:54         ` Jens Axboe
2019-01-29 16:55         ` Christoph Hellwig
2019-01-29 15:35   ` Jann Horn
2019-01-29 15:39     ` Jens Axboe
2019-01-29 19:26 [PATCHSET v9] " Jens Axboe
2019-01-29 19:26 ` [PATCH 05/18] Add " Jens Axboe
2019-01-30 21:55 [PATCHSET v10] " Jens Axboe
2019-01-30 21:55 ` [PATCH 05/18] Add " Jens Axboe
2019-02-01 15:23 [PATCHSET v11] " Jens Axboe
2019-02-01 15:24 ` [PATCH 05/18] Add " Jens Axboe
2019-02-01 18:20   ` Florian Weimer
2019-02-05 16:58     ` Jens Axboe
2019-02-04 23:22   ` Jeff Moyer
2019-02-04 23:52     ` Jeff Moyer
2019-02-05 16:59       ` Jens Axboe
2019-02-05 16:58     ` Jens Axboe
2019-02-07 19:55 [PATCHSET v12] " Jens Axboe
2019-02-07 19:55 ` [PATCH 05/18] Add " Jens Axboe
2019-02-07 20:15   ` Keith Busch
2019-02-07 20:16     ` Jens Axboe

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CAK8P3a1x4BsFfacxOmaDXKOKmmQ2j0ypX2+mCNCbjH3E7nC4DQ@mail.gmail.com \
    --to=arnd@arndb.de \
    --cc=avi@scylladb.com \
    --cc=axboe@kernel.dk \
    --cc=deepa.kernel@gmail.com \
    --cc=hch@lst.de \
    --cc=jmoyer@redhat.com \
    --cc=linux-aio@kvack.org \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-man@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).