Oleg Nesterov [oleg@xxxxxxxxxx] wrote:
| On 09/01, Oleg Nesterov wrote:
| >
| > On 08/31, sukadev@xxxxxxxxxx wrote:
| > >
| > > +static struct pid_namespace *get_task_pid_ns(struct task_struct *tsk)
| > > +{
| > > + struct pid *pid;
| > > + struct pid_namespace *ns;
| > > +
| > > + pid = get_task_pid(tsk, PIDTYPE_PID);
| > > + ns = get_pid_ns(pid_active_ns(pid));
| > > + put_pid(pid);
| > > +
| > > + return ns;
| > > +}
| >
| > Hmm. Firstly, we don't need this for the "current", but all users of this func
| > also do get_task_pid_ns(current).
| >
| > Also, we don't need get/put_pid. rcu locks are enough,
| >
| > rcu_read_lock();
| > ns = get_pid_ns(pid_active_ns(task_pid(tks)));
| > rcu_read_unlock();
| >
| > However, do we really need this complications right now? Currently, we use
| > this "compare namespaces" helpers only when we know that "struct pid" is
| > stable. We are sending the signal to that task, it must be pid_alive(), and
| > we either locked the task itself, or we hold tasklist.
|
| (forgot to mention)
|
| Otherwise, it is not safe to use "tsk" in get_task_pid_ns(), so I don't think
| these get/put pid/pid_ns games make too much sense.
get_pid(), put_pid(), get_pid_ns(), put_pid_ns() all allow pid to be NULL.
You mean tsk itself can be NULL bc task is exiting ?
|
| Oleg.
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