From: Jason Gunthorpe <jgg@ziepe.ca>
To: Brian Geffon <bgeffon@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Hillf Danton <hdanton@sina.com>, Peter Xu <peterx@redhat.com>,
linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Sonny Rao <sonnyrao@google.com>
Subject: Re: Userfaultfd doesn't seem to break out of poll on fd close
Date: Thu, 16 Apr 2020 11:49:42 -0300 [thread overview]
Message-ID: <20200416144942.GQ5100@ziepe.ca> (raw)
In-Reply-To: <CADyq12xg8vxetG8y=M6i2m4qYrtjsRhmpds-3yKTY2icrHG2GA@mail.gmail.com>
On Wed, Apr 15, 2020 at 06:15:26PM -0700, Brian Geffon wrote:
> And all of that I guess makes sense in the case of a non-blocking fd,
> but what about the case of a blocking file descriptor? Both
> userfaultfd and eventfd can seemingly be stuck in a read syscall with
> no way to break them out when the userfaultfd/eventfd has no further
> utility. Here is an example:
> https://gist.github.com/bgaff/607302d86d99ac539efca307ce2dd679
If an application wants to terminate blocking calls it has to rely on
signal delivery or pthread_cancel to end it.
This is very complicated so it is generally better to use poll and non
blocking.
Jason
prev parent reply other threads:[~2020-04-16 14:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-12 20:10 Userfaultfd doesn't seem to break out of poll on fd close Brian Geffon
2020-04-14 21:45 ` Peter Xu
2020-04-14 22:34 ` Jason Gunthorpe
2020-04-15 3:16 ` Hillf Danton
2020-04-15 14:25 ` Jason Gunthorpe
2020-04-15 15:16 ` Brian Geffon
2020-04-16 0:02 ` Andrea Arcangeli
2020-04-16 1:15 ` Brian Geffon
2020-04-16 1:37 ` Peter Xu
2020-04-16 4:39 ` Brian Geffon
2020-04-16 14:49 ` Jason Gunthorpe [this message]
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=20200416144942.GQ5100@ziepe.ca \
--to=jgg@ziepe.ca \
--cc=aarcange@redhat.com \
--cc=bgeffon@google.com \
--cc=hdanton@sina.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=peterx@redhat.com \
--cc=sonnyrao@google.com \
/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).