Messages in this thread | | | Date | Thu, 17 Nov 2011 16:32:00 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 3/3] pids: Make it possible to clone tasks with given pids |
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On 11/17, Pavel Emelyanov wrote: > > +static int set_pidmap(struct pid_namespace *pid_ns, int pid) > +{ > + int offset; > + struct pidmap *map; > + > + /* > + * When creating a new pid namespace we must make its init > + * have pid == 1 in it. > + */ > + if (pid_ns->child_reaper == NULL) > + return 0;
Do we really need this check? please see below...
> + /* > + * Don't allow to create a task with a pid which has recently > + * belonged to some other (dead already) task. Only init (of > + * a freshly created namespace) and his clones can do this. > + */ > + if (pid_ns->last_pid != 1) > + return -EPERM;
->last_pid == 1. This means that pid_nr == 1 was already created in this namespace via CLONE_NEWPID, and the child with this pid must be ->child_reaper, no?
IOW. if copy_process() allocs the first pid in the new pid_ns, it always sets ->child_reaper.
Cough. I really think 45a68628 should be reverted ;) IMHO it complicates the understanding of CLONE_NEWPID logic.
Oleg.
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