From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Triplett Subject: Re: [PATCH v2 7/7] clone4: Add a CLONE_FD flag to get task exit notification via fd Date: Mon, 6 Apr 2015 02:31:56 -0700 Message-ID: <20150406093154.GA22180@x> References: <20150406083035.GA16373@swordfish> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20150406083035.GA16373@swordfish> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sergey Senozhatsky Cc: Al Viro , Andrew Morton , Andy Lutomirski , Ingo Molnar , Kees Cook , Oleg Nesterov , "Paul E. McKenney" , "H. Peter Anvin" , Rik van Riel , Thomas Gleixner , Michael Kerrisk , Thiago Macieira , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org List-Id: linux-api@vger.kernel.org On Mon, Apr 06, 2015 at 05:30:35PM +0900, Sergey Senozhatsky wrote: > 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); ? No, once anon_inode_getfile has succeeded, the file owns the reference to the task_struct, so fput(file) will call the release function which calls put_task_struct. Only the failure case for anon_inode_getfile needs to call put_task_struct directly. > > + fput(file); > > + return fd; > > + } - Josh Triplett