[PATCH 07/16] signal: Wake up the designated parent

Eric W. Biederman
2022-05-18T22:53:46Z

Today if a process is ptraced only the ptracer will ever be woken up in
wait, if the parent is waiting with __WNOTHREAD. Update the code
so that the real_parent can also be woken up with __WNOTHREAD even
when the code is ptraced.

Fixes: 75b95953a569 ("job control: Add @for_ptrace to do_notify_parent_cldstop()")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
kernel/exit.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index f072959fcab7..0e26f73c49ac 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1421,26 +1421,35 @@ static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
return 0;
}

+struct child_wait_info {
+ struct task_struct *p;
+ struct task_struct *parent;
+};
+
static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
int sync, void *key)
{
struct wait_opts *wo = container_of(wait, struct wait_opts,
child_wait);
- struct task_struct *p = key;
+ struct child_wait_info *info = key;

- if (!eligible_pid(wo, p))
+ if (!eligible_pid(wo, info->p))
return 0;

- if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
- return 0;
+ if ((wo->wo_flags & __WNOTHREAD) && (wait->private != info->parent))
+ return 0;

return default_wake_function(wait, mode, sync, key);
}

void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
{
+ struct child_wait_info info = {
+ .p = p,
+ .parent = parent,
+ };
__wake_up_sync_key(&parent->signal->wait_chldexit,
- TASK_INTERRUPTIBLE, p);
+ TASK_INTERRUPTIBLE, &info);
}

static bool is_effectively_child(struct wait_opts *wo, bool ptrace,
--
2.35.3