diff options
| -rw-r--r-- | include/linux/pid.h | 3 | ||||
| -rw-r--r-- | kernel/fork.c | 26 | ||||
| -rw-r--r-- | kernel/pid.c | 2 | ||||
| -rw-r--r-- | kernel/signal.c | 11 |
4 files changed, 42 insertions, 0 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h index 3c8ef5a199ca..1484db6ca8d1 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -3,6 +3,7 @@ #define _LINUX_PID_H #include <linux/rculist.h> +#include <linux/wait.h> enum pid_type { @@ -60,6 +61,8 @@ struct pid unsigned int level; /* lists of tasks that use this pid */ struct hlist_head tasks[PIDTYPE_MAX]; + /* wait queue for pidfd notifications */ + wait_queue_head_t wait_pidfd; struct rcu_head rcu; struct upid numbers[1]; }; diff --git a/kernel/fork.c b/kernel/fork.c index b4cba953040a..2cdf295b72c7 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1704,8 +1704,34 @@ static void pidfd_show_fdinfo(struct seq_file *m, struct file *f) } #endif +/* + * Poll support for process exit notification. + */ +static unsigned int pidfd_poll(struct file *file, struct poll_table_struct *pts) +{ + struct task_struct *task; + struct pid *pid = file->private_data; + int poll_flags = 0; + + poll_wait(file, &pid->wait_pidfd, pts); + + rcu_read_lock(); + task = pid_task(pid, PIDTYPE_PID); + /* + * Inform pollers only when the whole thread group exits. + * If the thread group leader exits before all other threads in the + * group, then poll(2) should block, similar to the wait(2) family. + */ + if (!task || (task->exit_state && thread_group_empty(task))) + poll_flags = POLLIN | POLLRDNORM; + rcu_read_unlock(); + + return poll_flags; +} + const struct file_operations pidfd_fops = { .release = pidfd_release, + .poll = pidfd_poll, #ifdef CONFIG_PROC_FS .show_fdinfo = pidfd_show_fdinfo, #endif diff --git a/kernel/pid.c b/kernel/pid.c index 89548d35eefb..6ce3a95968f7 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -213,6 +213,8 @@ struct pid *alloc_pid(struct pid_namespace *ns) for (type = 0; type < PIDTYPE_MAX; ++type) INIT_HLIST_HEAD(&pid->tasks[type]); + init_waitqueue_head(&pid->wait_pidfd); + upid = pid->numbers + ns->level; spin_lock_irq(&pidmap_lock); if (!(ns->pid_allocated & PIDNS_ADDING)) diff --git a/kernel/signal.c b/kernel/signal.c index a1eb44dc9ff5..1c86b78a7597 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1803,6 +1803,14 @@ ret: return ret; } +static void do_notify_pidfd(struct task_struct *task) +{ + struct pid *pid; + + pid = task_pid(task); + wake_up_all(&pid->wait_pidfd); +} + /* * Let a parent know about the death of a child. * For a stopped/continued status change, use do_notify_parent_cldstop instead. @@ -1826,6 +1834,9 @@ bool do_notify_parent(struct task_struct *tsk, int sig) BUG_ON(!tsk->ptrace && (tsk->group_leader != tsk || !thread_group_empty(tsk))); + /* Wake up all pidfd waiters */ + do_notify_pidfd(tsk); + if (sig != SIGCHLD) { /* * This is only possible if parent == real_parent. |