From: Christian Brauner <brauner@kernel.org>
Date: Mon, 27 Mar 2023 18:22:52 +0000 (+0200)
Subject: fork: use pidfd_prepare()
X-Git-Tag: v6.6.7~3061^2~1
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ca7707f5430ad6b1c9cb7cee0a7f67d69328bb2d;p=platform%2Fkernel%2Flinux-starfive.git

fork: use pidfd_prepare()

Stop open-coding get_unused_fd_flags() and anon_inode_getfile(). That's
brittle just for keeping the flags between both calls in sync. Use the
dedicated helper.

Message-Id: <20230327-pidfd-file-api-v1-2-5c0e9a3158e4@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
---

diff --git a/kernel/fork.c b/kernel/fork.c
index a34395b..67bec6f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2376,21 +2376,12 @@ static __latent_entropy struct task_struct *copy_process(
 	 * if the fd table isn't shared).
 	 */
 	if (clone_flags & CLONE_PIDFD) {
-		retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
+		/* Note that no task has been attached to @pid yet. */
+		retval = __pidfd_prepare(pid, O_RDWR | O_CLOEXEC, &pidfile);
 		if (retval < 0)
 			goto bad_fork_free_pid;
-
 		pidfd = retval;
 
-		pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,
-					      O_RDWR | O_CLOEXEC);
-		if (IS_ERR(pidfile)) {
-			put_unused_fd(pidfd);
-			retval = PTR_ERR(pidfile);
-			goto bad_fork_free_pid;
-		}
-		get_pid(pid);	/* held by pidfile now */
-
 		retval = put_user(pidfd, args->pidfd);
 		if (retval)
 			goto bad_fork_put_pidfd;