From: Eric Biggers <ebiggers3@gmail.com>
To: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org, Hans Verkuil <hverkuil@xs4all.nl>,
Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
Shuah Khan <shuahkh@osg.samsung.com>,
linux-kernel@vger.kernel.org,
Gustavo Padovan <gustavo.padovan@collabora.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org,
Riley Andrews <riandrews@android.com>
Subject: Re: [PATCH v3 14/15] fs/files: export close_fd() symbol
Date: Thu, 7 Sep 2017 11:51:47 -0700 [thread overview]
Message-ID: <20170907185147.GB92996@gmail.com> (raw)
In-Reply-To: <20170907184226.27482-15-gustavo@padovan.org>
On Thu, Sep 07, 2017 at 03:42:25PM -0300, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.com>
>
> Rename __close_fd() to close_fd() and export it to be able close files
> in modules using file descriptors.
>
> The usecase that motivates this change happens in V4L2 where we send
> events to userspace with a fd that has file installed in it. But if for
> some reason we have to cancel the video stream we need to close the files
> that haven't been shared with userspace yet. Thus the export of
> close_fd() becomes necessary.
>
> fd_install() happens when we call an ioctl to queue a buffer, but we only
> share the fd with userspace later, and that may happen in a kernel thread
> instead.
What do you mean? A file descriptor is shared with userspace as soon as it's
installed in the fdtable by fd_install(). As soon as it's there, another thread
can use it (or close it, duplicate it, etc.), even before the syscall that
installed it returns...
Eric
next prev parent reply other threads:[~2017-09-07 18:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20170907184226.27482-1-gustavo@padovan.org>
2017-09-07 18:42 ` [PATCH v3 14/15] fs/files: export close_fd() symbol Gustavo Padovan
2017-09-07 18:51 ` Eric Biggers [this message]
2017-09-07 20:36 ` Al Viro
2017-09-07 21:22 ` Gustavo Padovan
2017-09-07 22:03 ` Al Viro
2017-09-07 22:09 ` Hans Verkuil
2017-09-07 22:18 ` Gustavo Padovan
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=20170907185147.GB92996@gmail.com \
--to=ebiggers3@gmail.com \
--cc=gustavo.padovan@collabora.com \
--cc=gustavo@padovan.org \
--cc=hverkuil@xs4all.nl \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=mchehab@osg.samsung.com \
--cc=riandrews@android.com \
--cc=shuahkh@osg.samsung.com \
--cc=viro@zeniv.linux.org.uk \
/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).