Two threads T1 and T2, and some process X (not the child of T1/T2).
T1 ptraces X.
X exits and becomes zombie.
T2 calls do_wait(WEXITED) and then wait_task_zombie(), it sets EXIT_DEAD
and drops tasklist.
T1 exits, calls exit_ptrace(). __ptrace_detach() does __ptrace_unlink()
and
Then the short-circuit test is simply if (!tsk-ptrace_info).
But, from the correctness pov, this doesn't differ from checking
!list_empty(-ptraced) ? I mean, the condition can be changed under us
in both cases, and we seem to have the same corner cases.
I guess it just seems simpler to me.
On 04/19, Roland McGrath wrote:
X-real_parent calls do_wait() and gets -ECHLD, because X is EXIT_DEAD
and not traced.
I see. I don't think we should worry especially about fixing this existing
bug (ancient, as you call it) on its own. So let's only consider this in
the context of the
On 04/16, Roland McGrath wrote:
But even that is a lot of hair for the incremental patches in the first
several stages, I think. So just never deallocate it, and:
static inline int task_ptrace(struct task_struct *task)
{
return unlikely(task-ptrace_child) ?
But, I still think we should do this fix before introducing -ptrace_mutex.
Ok by me if it's in fact (incrementally) simpler that way.
OK, we should avoid taking tasklist for writing. Then we should check
ptrace_reparented() first. If it is true get_task_struct, drop taslist,
take it for
