From: Oleg Nesterov <oleg@redhat.com>
To: Adrian Reber <areber@redhat.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>,
Eric Biederman <ebiederm@xmission.com>,
Pavel Emelyanov <ovzxemul@gmail.com>,
Jann Horn <jannh@google.com>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
linux-kernel@vger.kernel.org, Andrei Vagin <avagin@gmail.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Radostin Stoyanov <rstoyanov1@gmail.com>
Subject: Re: [PATCH v8 1/2] fork: extend clone3() to support setting a PID
Date: Wed, 13 Nov 2019 14:42:06 +0100 [thread overview]
Message-ID: <20191113134206.GA4320@redhat.com> (raw)
In-Reply-To: <20191113080301.1197762-1-areber@redhat.com>
On 11/13, Adrian Reber wrote:
>
> @@ -175,23 +187,47 @@ struct pid *alloc_pid(struct pid_namespace *ns)
>
> for (i = ns->level; i >= 0; i--) {
> int pid_min = 1;
Well, this is really minor but again, pid_min is only used in the "else"
branch below, you can move this declaration there.
> +
> + if (set_tid_size) {
> + tid = set_tid[ns->level - i];
> + if (tid < 1 || tid >= pid_max)
> + return ERR_PTR(-EINVAL);
> + /* Also fail if a PID != 1 is requested and no PID 1 exists */
> + if (tid != 1 && !tmp->child_reaper)
> + return ERR_PTR(-EINVAL);
> + if (!ns_capable(tmp->user_ns, CAP_SYS_ADMIN))
> + return ERR_PTR(-EPERM);
> + }
>
> idr_preload(GFP_KERNEL);
> spin_lock_irq(&pidmap_lock);
>
> - /*
> - * init really needs pid 1, but after reaching the maximum
> - * wrap back to RESERVED_PIDS
> - */
> - if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS)
> - pid_min = RESERVED_PIDS;
> -
> - /*
> - * Store a null pointer so find_pid_ns does not find
> - * a partially initialized PID (see below).
> - */
> - nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min,
> - pid_max, GFP_ATOMIC);
> + if (tid) {
> + nr = idr_alloc(&tmp->idr, NULL, tid,
> + tid + 1, GFP_ATOMIC);
> + /*
> + * If ENOSPC is returned it means that the PID is
> + * alreay in use. Return EEXIST in that case.
> + */
> + if (nr == -ENOSPC)
> + nr = -EEXIST;
> + set_tid_size--;
^^^^^^^^^^^^^^^
May I ask you to move this decrement into the "if (set_tid_size)" block above?
Oleg.
prev parent reply other threads:[~2019-11-13 13:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-13 8:03 [PATCH v8 1/2] fork: extend clone3() to support setting a PID Adrian Reber
2019-11-13 8:03 ` [PATCH v8 2/2] selftests: add tests for clone3() Adrian Reber
2019-11-13 12:35 ` Christian Brauner
2019-11-13 11:50 ` [PATCH v8 1/2] fork: extend clone3() to support setting a PID Christian Brauner
2019-11-13 13:42 ` Oleg Nesterov [this message]
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