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Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR API

From Oleg Nesterov <oleg@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR API
Date 2017-09-27 16:10 +0200
Message-ID <uulcf-44V-41@gated-at.bofh.it> (permalink)
References <uucLD-6o3-3@gated-at.bofh.it> <uucLD-6o3-1@gated-at.bofh.it> <uukpQ-3b4-27@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 09/27, Rik van Riel wrote:
>
> > @@ -240,17 +230,18 @@ void zap_pid_ns_processes(struct pid_namespace
> > *pid_ns)
> >  	 *
> >  	 */
> >  	read_lock(&tasklist_lock);
> > -	nr = next_pidmap(pid_ns, 1);
> > -	while (nr > 0) {
> > -		rcu_read_lock();
> > +	pid = idr_get_next(&pid_ns->idr, &nr);
> > +	while (pid) {
> >  
> > -		task = pid_task(find_vpid(nr), PIDTYPE_PID);
> > -		if (task && !__fatal_signal_pending(task))
> > -			send_sig_info(SIGKILL, SEND_SIG_FORCED,
> > task);
> > +		rcu_read_lock();
> >  
> > +		idr_for_each_entry_continue(&pid_ns->idr, pid, nr) {
> > +			task = pid_task(pid, PIDTYPE_PID);
> > +			if (task && !__fatal_signal_pending(task))
> > +				send_sig_info(SIGKILL,
> > SEND_SIG_FORCED, task);
> > +		}
> >  		rcu_read_unlock();
> >  
> > -		nr = next_pidmap(pid_ns, nr);
> >  	}
> >  	read_unlock(&tasklist_lock);
> >  
> 
> I believe we should be fine with just the idr_for_each_entry_continue()
> surrounding the loop,

Yes, and please move "nr = 2" close to idr_for_each_entry_continue() to
make it clear why do we use _continue (to skip nr == 1).

> and not need the while (pid) around that.
>
> That should still iterate over all the pids in the namespace, and
> simplify the code even more.

And make this patch correct ;)

because currently it is wrong, zap_pid_ns_processes() won't kill the pid
returned by the first idr_get_next().

Oleg.

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Thread

[PATCH v2 0/2] Replace PID bitmap allocation with IDR API Gargi Sharma <gs051095@gmail.com> - 2017-09-27 07:10 +0200
  [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR API Gargi Sharma <gs051095@gmail.com> - 2017-09-27 07:10 +0200
    Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR  API Rik van Riel <riel@surriel.com> - 2017-09-27 15:20 +0200
      Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR  API Oleg Nesterov <oleg@redhat.com> - 2017-09-27 16:10 +0200
        Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR API Gargi Sharma <gs051095@gmail.com> - 2017-09-27 17:10 +0200
          Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR  API Oleg Nesterov <oleg@redhat.com> - 2017-09-27 17:20 +0200
      Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR API Gargi Sharma <gs051095@gmail.com> - 2017-09-27 17:10 +0200
    Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR  API Oleg Nesterov <oleg@redhat.com> - 2017-09-27 17:10 +0200
    Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR  API Christoph Hellwig <hch@infradead.org> - 2017-10-01 11:20 +0200
      Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR API Gargi Sharma <gs051095@gmail.com> - 2017-10-01 12:40 +0200
        Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR  API Rik van Riel <riel@surriel.com> - 2017-10-02 15:20 +0200
      Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR  API Rik van Riel <riel@surriel.com> - 2017-10-02 15:10 +0200
  [PATCH v2 2/2] pid: Remove pidhash Gargi Sharma <gs051095@gmail.com> - 2017-09-27 07:10 +0200
    Re: [PATCH v2 2/2] pid: Remove pidhash Oleg Nesterov <oleg@redhat.com> - 2017-09-27 17:50 +0200
      Re: [PATCH v2 2/2] pid: Remove pidhash Oleg Nesterov <oleg@redhat.com> - 2017-09-27 18:30 +0200
        Re: [PATCH v2 2/2] pid: Remove pidhash Gargi Sharma <gs051095@gmail.com> - 2017-09-30 17:50 +0200
      Re: [PATCH v2 2/2] pid: Remove pidhash Rik van Riel <riel@surriel.com> - 2017-10-02 22:50 +0200
        Re: [PATCH v2 2/2] pid: Remove pidhash Gargi Sharma <gs051095@gmail.com> - 2017-10-02 22:50 +0200
      Re: [PATCH v2 2/2] pid: Remove pidhash Oleg Nesterov <oleg@redhat.com> - 2017-10-02 22:50 +0200
      Re: [PATCH v2 2/2] pid: Remove pidhash Rik van Riel <riel@surriel.com> - 2017-10-02 22:50 +0200
  Re: [PATCH v2 0/2] Replace PID bitmap allocation with IDR API ebiederm@xmission.com (Eric W. Biederman) - 2017-09-27 19:20 +0200
    Re: [PATCH v2 0/2] Replace PID bitmap allocation with IDR API Rik van Riel <riel@surriel.com> - 2017-09-28 21:50 +0200
      Re: [PATCH v2 0/2] Replace PID bitmap allocation with IDR API Gargi Sharma <gs051095@gmail.com> - 2017-09-28 22:10 +0200
        Re: [PATCH v2 0/2] Replace PID bitmap allocation with IDR API Rik van Riel <riel@surriel.com> - 2017-09-29 02:40 +0200

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