Re: [PATCH v2 7/7] clone4: Add a CLONE_FD flag to get task exit notification via fd

From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Josh Triplett <josh@joshtriplett.org>
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 7/7] clone4: Add a CLONE_FD flag to get task exit notification via fd
Date: Mon, 6 Apr 2015 17:30:35 +0900	[thread overview]
Message-ID: <20150406083035.GA16373@swordfish> (raw)
In-Reply-To: <fdec4b70c7cd34e2eacf6a0e41d36f606a696da1.1426376419.git.josh@joshtriplett.org>

On (03/15/15 01:00), Josh Triplett wrote:
[..]
> +
> +/* Handle the CLONE_FD case for copy_process. */
> +int clonefd_do_clone(u64 clone_flags, struct task_struct *p,
> +		     struct clone4_args *args, struct clonefd_setup *setup)
> +{
> +	int flags;
> +	struct file *file;
> +	int fd;
> +
> +	p->clonefd = !!(clone_flags & CLONE_FD);
> +	if (!p->clonefd)
> +		return 0;
> +
> +	if (args->clonefd_flags & ~(O_CLOEXEC | O_NONBLOCK))
> +		return -EINVAL;
> +
> +	init_waitqueue_head(&p->clonefd_wqh);
> +
> +	get_task_struct(p);
> +	flags = O_RDONLY | FMODE_ATOMIC_POS | args->clonefd_flags;
> +	file = anon_inode_getfile("[process]", &clonefd_fops, p, flags);
> +	if (IS_ERR(file)) {
> +		put_task_struct(p);
> +		return PTR_ERR(file);
> +	}
> +
> +	fd = get_unused_fd_flags(flags);
> +	if (fd < 0) {

+		put_task_struct(p); ?

> +		fput(file);
> +		return fd;
> +	}
> +
> +	setup->fd = fd;
> +	setup->file = file;
> +	return 0;
> +}
[..]

	-ss