coredump: replace the startup completion with a thread count

coredump_wait() sets core_state->nr_threads to the number of tasks
killed and waits for the last thread to enter coredump_task_exit() to
signal completion. Let's just wait on the count directly. The exiting
tasks can use atomic_dec_and_wake_up() and the dumping task sleeps in
wait_var_event_state().

The dumping task must remain freezable since commit f5d39b020809
("freezer,sched: Rewrite core freezer logic"). So keep the wait
TASK_UNINTERRUPTIBLE|TASK_FREEZABLE.

Drop the completion and rename nr_threads to threads_remaining.

No functional changes.

Suggested-by: NeilBrown <neilb@ownmail.net>
Link: https://lore.kernel.org/178899497961.207413.10554121774377911612@noble.neil.brown.name
Link: https://patch.msgid.link/20260910-work-coredump-unlock-self-v4-12-a5c1800dc930@kernel.org
Reviewed-by: NeilBrown <neil@brown.name>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

0 files changed, 0 insertions, 0 deletions