Date: Tue, 12 Apr 2016 17:39:14 -0700
From: Andrew Vagin <avagin@gmail.com>
To: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Andrey Vagin <avagin@openvz.org>, linux-kernel@vger.kernel.org,
        Oleg Nesterov <oleg@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Pavel Emelyanov <xemul@parallels.com>, Roger Luethi <rl@hellgate.ch>,
        Arnd Bergmann <arnd@arndb.de>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        David Ahern <dsahern@gmail.com>, Andy Lutomirski <luto@amacapital.net>,
        Pavel Odintsov <pavel.odintsov@gmail.com>
Subject: Re: [PATCH 04/15] task_diag: add a new interface to get information
 about tasks (v4)
Message-ID: <20160413003913.GB18121@gmail.com>
References: <1460417755-18201-1-git-send-email-avagin@openvz.org>
 <1460417755-18201-5-git-send-email-avagin@openvz.org>
 <20160412070857.GU2000@uranus.lan>
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On Tue, Apr 12, 2016 at 10:08:57AM +0300, Cyrill Gorcunov wrote:
> On Mon, Apr 11, 2016 at 04:35:44PM -0700, Andrey Vagin wrote:
> ...
> > +static int __taskdiag_dumpit(struct task_iter *iter,
> > +			     struct task_diag_cb *cb, struct task_struct **start)
> > +{
> > +	struct user_namespace *userns = current_user_ns();
> > +	struct task_struct *task = *start;
> > +	int rc;
> > +
> > +	for (; task; task = iter_next(iter)) {
> > +		if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
> > +			continue;
> > +
> > +		rc = task_diag_fill(task, cb->resp, &iter->req,
> > +				cb, iter->ns, userns);
> > +		if (rc < 0) {
> > +			if (rc != -EMSGSIZE)
> > +				return rc;
> > +			break;

task isn't NULL here

> > +		}
> > +	}
> > +	*start = task;
> 
> task = NULL always here?

No, it isn't if the loop is interrupted by break.

Thanks,
Andrew