From: Fabio Baltieri <fabio.baltieri@gmail.com>
To: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Wolfgang Grandegger <wg@grandegger.com>,
linux-can@vger.kernel.org, linux-kernel@vger.kernel.org,
Oliver Hartkopp <socketcan@hartkopp.net>
Subject: Re: [PATCH can-next v3 1/2] can: add tx/rx LED trigger support
Date: Tue, 31 Jul 2012 13:55:39 +0200 [thread overview]
Message-ID: <20120731115539.GA30417@gmail.com> (raw)
In-Reply-To: <5017AFAB.1040609@pengutronix.de>
On Tue, Jul 31, 2012 at 12:12:59PM +0200, Marc Kleine-Budde wrote:
> >> +/*
> >> + * Register CAN LED triggers for a CAN device
> >> + *
> >> + * This is normally called from a driver's probe function
> >> + */
> >> +void can_led_init(struct net_device *netdev)
> >> +{
> >> + struct can_priv *priv = netdev_priv(netdev);
> >> +
> >> + priv->tx_led_trig_name = kasprintf(GFP_KERNEL, "%s-tx", netdev->name);
> >> + if (!priv->tx_led_trig_name)
> >> + goto tx_led_failed;
> >
> > Just return here?
Right.
> >> + priv->rx_led_trig_name = kasprintf(GFP_KERNEL, "%s-rx", netdev->name);
> >> + if (!priv->rx_led_trig_name)
> >> + goto rx_led_failed;
> >> +
> >> + led_trigger_register_simple(priv->tx_led_trig_name,
> >> + &priv->tx_led_trig);
> >> + led_trigger_register_simple(priv->rx_led_trig_name,
> >> + &priv->rx_led_trig);
> >> +
> >> + return;
> >> +
> >> +rx_led_failed:
> >> + kfree(priv->tx_led_trig_name);
> >> + priv->tx_led_trig_name = NULL;
> >> +tx_led_failed:
> >> + return;
> >
> > In case of error the function returns silently. Is this by purpose? What
> > happens if CAN_LEDS is enabled but no LEDs are assigned?
>
> It's a bit strange, but led_trigger_register_simple() can fail silently,
> too. Or better it has no return value, but does a warning printk in case
> of an error.
Well, that's in line with the behviour of leds trigger registration in
other subsystems out there (mac80211 and power_supply for instance) but
now that you pointed it out, I agree that this is not really nice to the
user. led_trigger_register_simple already has a printk to KERN_ERR, I
may add another one in the error path (if we keep the kasprintf).
>
> >
> >> +}
> >> +EXPORT_SYMBOL_GPL(can_led_init);
> >> +
> >> +/*
> >> + * Unregister CAN LED triggers for a CAN device
> >> + *
> >> + * This is normally called from a driver's remove function
> >> + */
> >> +void can_led_exit(struct net_device *netdev)
> >> +{
> >> + struct can_priv *priv = netdev_priv(netdev);
> >> +
> >> + led_trigger_unregister_simple(priv->tx_led_trig);
> >> + led_trigger_unregister_simple(priv->rx_led_trig);
> >> +
> >> + kfree(priv->tx_led_trig_name);
> >> + kfree(priv->rx_led_trig_name);
> >> +}
> >> +EXPORT_SYMBOL_GPL(can_led_exit);
> >> diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
> >> index 2b2fc34..167b04a 100644
> >> --- a/include/linux/can/dev.h
> >> +++ b/include/linux/can/dev.h
> >> @@ -16,6 +16,7 @@
> >> #include <linux/can.h>
> >> #include <linux/can/netlink.h>
> >> #include <linux/can/error.h>
> >> +#include <linux/can/led.h>
> >>
> >> /*
> >> * CAN mode
> >> @@ -52,6 +53,13 @@ struct can_priv {
> >>
> >> unsigned int echo_skb_max;
> >> struct sk_buff **echo_skb;
> >> +
> >> +#ifdef CONFIG_CAN_LEDS
> >> + struct led_trigger *tx_led_trig;
> >> + char *tx_led_trig_name;
> >> + struct led_trigger *rx_led_trig;
> >> + char *rx_led_trig_name;
> >> +#endif
> >
> > Do we need to store the names?
>
> Yes, Seems, so the name is not copied:
>
> http://lxr.free-electrons.com/source/drivers/leds/led-triggers.c#L253
>
> Marc
Actually we may try to exploit struct led_trigger to get back the
pointers, but then we have to free the names before calling
led_trigger_unregister, and that's going to be race against
led_trigger_show(). Anyway, those pointers would go away using a
devm-based allocation, so I'll keep that in mind.
Thanks,
Fabio
next prev parent reply other threads:[~2012-07-31 11:53 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-30 19:20 [PATCH can-next v3 1/2] can: add tx/rx LED trigger support Fabio Baltieri
2012-07-30 19:20 ` [PATCH can-next v3 2/2] can: flexcan: add " Fabio Baltieri
2012-07-30 21:17 ` [PATCH can-next v3 1/2] can: add tx/rx " Marc Kleine-Budde
2012-07-31 6:57 ` Fabio Baltieri
2012-07-31 7:10 ` Marc Kleine-Budde
2012-07-31 11:57 ` Fabio Baltieri
2012-07-31 12:00 ` Marc Kleine-Budde
2012-07-31 22:05 ` [PATCH can-next v4] " Fabio Baltieri
2012-08-01 9:36 ` Marc Kleine-Budde
2012-08-01 10:07 ` Marc Kleine-Budde
2012-08-01 10:30 ` Fabio Baltieri
2012-08-01 11:37 ` Marc Kleine-Budde
2012-08-01 11:49 ` [PATCH can-next v5 1/2] " Fabio Baltieri
2012-08-01 11:49 ` [PATCH can-next v5 2/2] can: flexcan: add " Fabio Baltieri
2012-08-01 11:53 ` Marc Kleine-Budde
2012-08-01 12:24 ` Fabio Baltieri
2012-08-01 12:30 ` Marc Kleine-Budde
2012-08-01 21:02 ` Marc Kleine-Budde
2012-08-01 11:59 ` [PATCH can-next v5 1/2] can: add tx/rx " Marc Kleine-Budde
2012-08-01 12:06 ` Oliver Hartkopp
2012-08-01 12:18 ` Marc Kleine-Budde
2012-08-01 18:21 ` [PATCH can-next v6] " Fabio Baltieri
2012-08-01 21:00 ` Marc Kleine-Budde
2012-08-01 22:38 ` Fabio Baltieri
2012-08-01 21:05 ` Oliver Hartkopp
2012-08-24 5:10 ` Kurt Van Dijck
2012-08-24 11:28 ` Marc Kleine-Budde
2012-08-24 12:42 ` Kurt Van Dijck
2012-08-24 22:01 ` Fabio Baltieri
2012-08-25 20:25 ` Kurt Van Dijck
2012-09-03 12:40 ` Marc Kleine-Budde
2012-09-03 18:13 ` Kurt Van Dijck
2012-09-03 18:29 ` Fabio Baltieri
2012-09-03 20:54 ` Oliver Hartkopp
2012-09-04 7:11 ` Kurt Van Dijck
2012-09-04 9:29 ` [PATCH] can: rename LED trigger name on netdev renames Kurt Van Dijck
2012-09-06 18:59 ` Fabio Baltieri
2012-09-06 19:31 ` Oliver Hartkopp
2012-09-06 20:46 ` Fabio Baltieri
2012-09-07 7:19 ` Kurt Van Dijck
2012-09-09 16:17 ` [PATCH v2] " Fabio Baltieri
2012-09-10 14:25 ` [PATCH] can: export a safe netdev_priv wrapper for candev Kurt Van Dijck
2012-09-10 18:22 ` Oliver Hartkopp
2012-09-10 18:29 ` Fabio Baltieri
2012-09-10 19:55 ` [PATCH v2] " Kurt Van Dijck
2012-09-10 14:28 ` [PATCH v3] can: rename LED trigger name on netdev renames Kurt Van Dijck
2012-09-10 18:25 ` Oliver Hartkopp
2012-09-10 18:40 ` Fabio Baltieri
2012-09-10 19:01 ` Oliver Hartkopp
2012-09-10 20:08 ` Kurt Van Dijck
2012-09-11 5:42 ` Oliver Hartkopp
2012-09-11 7:13 ` Fabio Baltieri
2012-09-12 7:22 ` Kurt Van Dijck
2012-09-11 8:05 ` Kurt Van Dijck
2012-09-10 20:06 ` [PATCH v4] " Kurt Van Dijck
2012-09-11 21:04 ` Fabio Baltieri
2012-09-04 20:15 ` [PATCH can-next v6] can: add tx/rx LED trigger support Fabio Baltieri
2012-09-06 10:33 ` Kurt Van Dijck
2012-09-06 11:17 ` Fabio Baltieri
2012-09-06 15:11 ` Kurt Van Dijck
2012-09-06 20:57 ` Fabio Baltieri
2012-09-07 7:04 ` Kurt Van Dijck
2012-09-07 18:59 ` Fabio Baltieri
2012-07-31 8:46 ` [PATCH can-next v3 1/2] " Wolfgang Grandegger
2012-07-31 10:12 ` Marc Kleine-Budde
2012-07-31 11:55 ` Fabio Baltieri [this message]
2012-07-31 12:14 ` Fabio Baltieri
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