Commit cdefbf23 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Christian Brauner
Browse files

pidfd: cleanup the usage of __pidfd_prepare's flags 



- make pidfd_create() static.

- Don't pass O_RDWR | O_CLOEXEC to __pidfd_prepare() in copy_process(),
  __pidfd_prepare() adds these flags unconditionally.

- Kill the flags check in __pidfd_prepare(). sys_pidfd_open() checks the
  flags itself, all other users of pidfd_prepare() pass flags = 0.

  If we need a sanity check for those other in kernel users then
  WARN_ON_ONCE(flags & ~PIDFD_NONBLOCK) makes more sense.

- Don't pass O_RDWR to get_unused_fd_flags(), it ignores everything except
  O_CLOEXEC.

- Don't pass O_CLOEXEC to anon_inode_getfile(), it ignores everything except
  O_ACCMODE | O_NONBLOCK.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20240125161734.GA778@redhat.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent b639585e

include/linux/pid.h

+0 −1
Original line number Diff line number Diff line
@@ -73,7 +73,6 @@ struct file; 
extern struct pid *pidfd_pid(const struct file *file);

struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags);

struct task_struct *pidfd_get_task(int pidfd, unsigned int *flags);

int pidfd_create(struct pid *pid, unsigned int flags);

int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret);



static inline struct pid *get_pid(struct pid *pid)

kernel/fork.c

+3 −6
Original line number Diff line number Diff line
@@ -2130,15 +2130,12 @@ static int __pidfd_prepare(struct pid *pid, unsigned int flags, struct file **re 
	int pidfd;

	struct file *pidfd_file;



	if (flags & ~(O_NONBLOCK | O_RDWR | O_CLOEXEC))

		return -EINVAL;



	pidfd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);

	pidfd = get_unused_fd_flags(O_CLOEXEC);

	if (pidfd < 0)

		return pidfd;



	pidfd_file = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,

					flags | O_RDWR | O_CLOEXEC);

					flags | O_RDWR);

	if (IS_ERR(pidfd_file)) {

		put_unused_fd(pidfd);

		return PTR_ERR(pidfd_file);
@@ -2524,7 +2521,7 @@ __latent_entropy struct task_struct *copy_process( 
	 */

	if (clone_flags & CLONE_PIDFD) {

		/* Note that no task has been attached to @pid yet. */

		retval = __pidfd_prepare(pid, O_RDWR | O_CLOEXEC, &pidfile);

		retval = __pidfd_prepare(pid, 0, &pidfile);

		if (retval < 0)

			goto bad_fork_free_pid;

		pidfd = retval;

kernel/pid.c

+1 −1
Original line number Diff line number Diff line
@@ -595,7 +595,7 @@ struct task_struct *pidfd_get_task(int pidfd, unsigned int *flags) 
 * Return: On success, a cloexec pidfd is returned.

 *         On error, a negative errno number will be returned.

 */

int pidfd_create(struct pid *pid, unsigned int flags)

static int pidfd_create(struct pid *pid, unsigned int flags)

{

	int pidfd;

	struct file *pidfd_file;