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pidfd: change do_notify_pidfd() to use __wake_up(poll_to_key(EPOLLIN))

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rather than wake_up_all(). This way do_notify_pidfd() won't wakeup the
POLLHUP-only waiters which wait for pid_task() == NULL.

TODO:
    - as Christian pointed out, this asks for the new wake_up_all_poll()
      helper, it can already have other users.

    - we can probably discriminate the PIDFD_THREAD and non-PIDFD_THREAD
      waiters, but this needs more work. See
      https://lore.kernel.org/all/20240205140848.GA15853@redhat.com/

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20240205141348.GA16539@redhat.com
Reviewed-by: Tycho Andersen <tandersen@netflix.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Oleg Nesterov 2024-02-05 15:13:48 +01:00 committed by Christian Brauner
parent a1c6d5439f
commit 9ed52108f6
1 changed files with 4 additions and 3 deletions
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7
kernel/signal.c
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@ -2021,11 +2021,12 @@ ret:
void do_notify_pidfd(struct task_struct *task)
{
struct pid *pid;
struct pid *pid = task_pid(task);
WARN_ON(task->exit_state == 0);
pid = task_pid(task);
wake_up_all(&pid->wait_pidfd);
__wake_up(&pid->wait_pidfd, TASK_NORMAL, 0,
poll_to_key(EPOLLIN | EPOLLRDNORM));
}
/*