From: Sven Eckelmann <sven@narfation.org>
To: b.a.t.m.a.n@lists.open-mesh.org
Cc: Marek Lindner <mareklindner@neomailbox.ch>,
Antonio Quartulli <a@unstable.cc>
Subject: Re: [B.A.T.M.A.N.] [PATCH v2 1/7] batman-adv: tp_meter - prevent concurrent tp_meter sessions by using workqueue
Date: Wed, 29 Aug 2018 08:56:47 +0200 [thread overview]
Message-ID: <2069569.jAo6mdz6e2@bentobox> (raw)
In-Reply-To: <20180518014754.23644-2-mareklindner@neomailbox.ch>
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Hi,
looks like you have reference counting issues here:
On Freitag, 18. Mai 2018 09:47:48 CEST Marek Lindner wrote:
> -static void batadv_tp_start_kthread(struct batadv_tp_vars *tp_vars)
> +static void batadv_tp_start_work(struct batadv_tp_vars *tp_vars)
> {
> - struct task_struct *kthread;
> - struct batadv_priv *bat_priv = tp_vars->bat_priv;
> - u32 session_cookie;
> -
> - kref_get(&tp_vars->refcount);
> - kthread = kthread_create(batadv_tp_send, tp_vars, "kbatadv_tp_meter");
> - if (IS_ERR(kthread)) {
> - session_cookie = batadv_tp_session_cookie(tp_vars->session,
> - tp_vars->icmp_uid);
> - pr_err("batadv: cannot create tp meter kthread\n");
> - batadv_tp_batctl_error_notify(BATADV_TP_REASON_MEMORY_ERROR,
> - tp_vars->other_end,
> - bat_priv, session_cookie);
> -
> - /* drop reserved reference for kthread */
> - batadv_tp_vars_put(tp_vars);
> -
> - /* cleanup of failed tp meter variables */
> - batadv_tp_sender_cleanup(bat_priv, tp_vars);
> - return;
> - }
> -
> - wake_up_process(kthread);
> + /* init work item that will actually execute the test and schedule it */
> + INIT_WORK(&tp_vars->test_work, batadv_tp_send);
> + queue_work(batadv_tp_meter_queue, &tp_vars->test_work);
> }
You completely ignore here that queue_work can fail. And then you have an item
with a reference counter > 0 in memory and no one cares about it.
>
> /**
> @@ -1053,13 +1035,10 @@ void batadv_tp_start(struct batadv_priv *bat_priv, const u8 *dst,
> /* init work item for finished tp tests */
> INIT_DELAYED_WORK(&tp_vars->finish_work, batadv_tp_sender_finish);
>
> - /* start tp kthread. This way the write() call issued from userspace can
> - * happily return and avoid to block
> + /* schedule the tp worker. This way the write() call issued from
> + * userspace can happily return and avoid to block
> */
> - batadv_tp_start_kthread(tp_vars);
> -
> - /* don't return reference to new tp_vars */
> - batadv_tp_vars_put(tp_vars);
> + batadv_tp_start_work(tp_vars);
> }
Just from the context of this function, it isn't clear what happened with the
reference.
Kind regards,
Sven
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next prev parent reply other threads:[~2018-08-29 6:56 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-18 1:47 [B.A.T.M.A.N.] [PATCH v2 0/7] B.A.T.M.A.N. V - fallback to tp meter estimation if throughput otherwise not available Marek Lindner
2018-05-18 1:47 ` [B.A.T.M.A.N.] [PATCH v2 1/7] batman-adv: tp_meter - prevent concurrent tp_meter sessions by using workqueue Marek Lindner
2018-08-29 6:56 ` Sven Eckelmann [this message]
2018-05-18 1:47 ` [B.A.T.M.A.N.] [PATCH v2 2/7] batman-adv: tp_meter - don't check for existing session Marek Lindner
2018-05-18 1:47 ` [B.A.T.M.A.N.] [PATCH v2 3/7] batman-adv: tp_meter - allow up to 10 queued sessions Marek Lindner
2018-05-18 1:47 ` [B.A.T.M.A.N.] [PATCH v2 4/7] batman-adv: tp_meter - add caller distinction Marek Lindner
2018-05-18 1:47 ` [B.A.T.M.A.N.] [PATCH v2 5/7] batman-adv: tp_meter - add option to perform one-hop test Marek Lindner
2018-05-18 1:47 ` [B.A.T.M.A.N.] [PATCH v2 6/7] batman-adv: ELP - use tp meter to estimate the throughput if otherwise not available Marek Lindner
2018-05-21 13:17 ` Linus Lüssing
2018-05-21 17:51 ` Sven Eckelmann
2018-05-21 19:06 ` Sven Eckelmann
2018-08-04 9:31 ` Antonio Quartulli
2018-05-21 14:43 ` Linus Lüssing
2018-08-04 9:35 ` Marek Lindner
2018-05-21 14:48 ` Linus Lüssing
2018-08-04 9:39 ` Antonio Quartulli
2018-05-21 15:01 ` Linus Lüssing
2018-08-04 8:59 ` Antonio Quartulli
2018-05-21 16:36 ` Sven Eckelmann
2018-05-18 1:47 ` [B.A.T.M.A.N.] [PATCH v2 7/7] batman-adv: ELP - add throughput meter test duration attribute Marek Lindner
2018-05-21 13:46 ` Linus Lüssing
2018-05-21 13:57 ` Linus Lüssing
2018-08-04 9:05 ` Marek Lindner
2018-05-21 14:34 ` Sven Eckelmann
2018-08-04 8:41 ` Antonio Quartulli
2018-08-04 9:02 ` Sven Eckelmann
2018-08-04 9:08 ` Antonio Quartulli
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