From: josh@joshtriplett.org
To: Jonathan Corbet <corbet@lwn.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Kees Cook <keescook@chromium.org>,
Oleg Nesterov <oleg@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
"H. Peter Anvin" <hpa@zytor.com>, Rik van Riel <riel@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Thiago Macieira <thiago.macieira@intel.com>,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
linux-fsdevel@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH v2 0/7] CLONE_FD: Task exit notification via file descriptor
Date: Tue, 31 Mar 2015 15:02:24 -0700 [thread overview]
Message-ID: <20150331220224.GA22707@cloud> (raw)
In-Reply-To: <20150331220807.6927e780@lwn.net>
On Tue, Mar 31, 2015 at 10:08:07PM +0200, Jonathan Corbet wrote:
> So I finally got around to having a look at this, and one thing caught my
> eye:
>
> > read(2) (and similar)
> > When the new process exits, reading from the file
> > descriptor produces a single clonefd_info structure:
> >
> > struct clonefd_info {
> > uint32_t code; /* Signal code */
> > uint32_t status; /* Exit status or signal */
> > uint64_t utime; /* User CPU time */
> > uint64_t stime; /* System CPU time */
> > };
>
> This would appear to assume that a clonefd_info structure is the only
> thing that will ever be read from this descriptor. It seems to me that
> there is the potential for, someday, wanting to be able to read and write
> other things as well. Should this structure be marked with type and
> length fields so that other structures could be added in the future?
I don't think it makes sense for a caller to get an arbitrary structure
on read(), and have to figure out what they got and ignore something
they don't understand. Instead, I think it makes more sense for the
caller to say "Hey, here's a flag saying I understand the new thing, go
ahead and give me the new thing". So, for instance, if you want to
receive SIGSTOP/SIGCONT messages for child processes through this
descriptor, we could add a flag for that.
- Josh Triplett
next prev parent reply other threads:[~2015-03-31 22:02 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-15 7:59 [PATCH v2 0/7] CLONE_FD: Task exit notification via file descriptor Josh Triplett
2015-03-15 7:59 ` [PATCH v2 1/7] clone: Support passing tls argument via C rather than pt_regs magic Josh Triplett
2015-03-15 7:59 ` [PATCH v2 2/7] x86: Opt into HAVE_COPY_THREAD_TLS, for both 32-bit and 64-bit Josh Triplett
2015-03-15 7:59 ` [PATCH v2 3/7] Introduce a new clone4 syscall with more flag bits and extensible arguments Josh Triplett
2015-03-23 14:11 ` David Drysdale
2015-03-23 15:05 ` josh
2015-03-31 14:41 ` David Drysdale
2015-03-15 7:59 ` [PATCH v2 4/7] kernel/fork.c: Pass arguments to _do_fork and copy_process using clone4_args Josh Triplett
2015-03-15 8:00 ` [PATCH v2 5/7] clone4: Add a CLONE_AUTOREAP flag to automatically reap the child process Josh Triplett
2015-03-15 14:52 ` Oleg Nesterov
2015-03-15 17:18 ` Josh Triplett
2015-03-15 19:55 ` Oleg Nesterov
2015-03-15 23:34 ` Josh Triplett
2015-03-20 18:14 ` Oleg Nesterov
2015-03-20 18:46 ` Thiago Macieira
2015-03-20 19:09 ` Oleg Nesterov
2015-03-20 21:10 ` josh
2015-03-15 8:00 ` [PATCH v2 6/7] signal: Factor out a helper function to process task_struct exit_code Josh Triplett
2015-03-15 8:00 ` [PATCH v2 7/7] clone4: Add a CLONE_FD flag to get task exit notification via fd Josh Triplett
2015-03-23 17:38 ` David Drysdale
2015-03-25 14:53 ` Josh Triplett
2015-04-06 8:30 ` Sergey Senozhatsky
2015-04-06 9:31 ` Josh Triplett
2015-03-15 8:00 ` [PATCH v2 man-pages] clone4.2: New manpage documenting clone4(2) Josh Triplett
2015-03-15 8:04 ` [PATCH v2 0/7] CLONE_FD: Task exit notification via file descriptor Josh Triplett
2015-03-16 21:44 ` Kees Cook
2015-03-16 22:14 ` Thiago Macieira
2015-03-16 22:36 ` Kees Cook
2015-03-16 22:50 ` Thiago Macieira
2015-03-16 23:26 ` Kees Cook
2015-03-16 23:35 ` josh
2015-03-16 23:29 ` josh
2015-03-17 0:49 ` Thiago Macieira
2015-03-23 14:12 ` David Drysdale
2015-03-23 15:03 ` josh
2015-03-16 23:25 ` josh
2015-03-31 20:08 ` Jonathan Corbet
2015-03-31 22:02 ` josh [this message]
2015-04-01 7:24 ` Jonathan Corbet
2015-04-09 2:19 ` Josh Triplett
2015-05-29 7:43 ` Florian Weimer
2015-05-29 20:27 ` Thiago Macieira
2015-06-15 10:06 ` Florian Weimer
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