diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2024-01-31 14:26:02 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-02-02 13:12:28 +0100 |
| commit | 64bef697d33b75fc06c5789b3f8108680271529f (patch) | |
| tree | dacc56670ce9a76cb7252e69dd88fcdeb7d72f2f /include/linux/pid.h | |
| parent | 21e25205d7f9b6d7d3807546dd12ea93844b7c8e (diff) | |
pidfd: implement PIDFD_THREAD flag for pidfd_open()
With this flag:
- pidfd_open() doesn't require that the target task must be
a thread-group leader
- pidfd_poll() succeeds when the task exits and becomes a
zombie (iow, passes exit_notify()), even if it is a leader
and thread-group is not empty.
This means that the behaviour of pidfd_poll(PIDFD_THREAD,
pid-of-group-leader) is not well defined if it races with
exec() from its sub-thread; pidfd_poll() can succeed or not
depending on whether pidfd_task_exited() is called before
or after exchange_tids().
Perhaps we can improve this behaviour later, pidfd_poll()
can probably take sig->group_exec_task into account. But
this doesn't really differ from the case when the leader
exits before other threads (so pidfd_poll() succeeds) and
then another thread execs and pidfd_poll() will block again.
thread_group_exited() is no longer used, perhaps it can die.
Co-developed-by: Tycho Andersen <tycho@tycho.pizza>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20240131132602.GA23641@redhat.com
Tested-by: Tycho Andersen <tandersen@netflix.com>
Reviewed-by: Tycho Andersen <tandersen@netflix.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'include/linux/pid.h')
| -rw-r--r-- | include/linux/pid.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h index e6a041cb8bac..8124d57752b9 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -70,10 +70,11 @@ extern const struct file_operations pidfd_fops; struct file; -extern struct pid *pidfd_pid(const struct file *file); +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_prepare(struct pid *pid, unsigned int flags, struct file **ret); +void do_notify_pidfd(struct task_struct *task); static inline struct pid *get_pid(struct pid *pid) { |