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From: "Ahmed S. Darwish" <darwish.07@gmail.com>
To: Andri Yngvason <andri.yngvason@marel.com>
Cc: Olivier Sobrie <olivier@sobrie.be>,
	Oliver Hartkopp <socketcan@hartkopp.net>,
	Wolfgang Grandegger <wg@grandegger.com>,
	Marc Kleine-Budde <mkl@pengutronix.de>,
	Linux-CAN <linux-can@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 2/5] can: kvaser_usb: Consolidate and unify state change handling
Date: Sun, 25 Jan 2015 05:21:47 +0200
Message-ID: <20150125032147.GB6621@Darwish.PC> (raw)
In-Reply-To: <20150121162025.2933.13836@shannon>

Hi!

On Wed, Jan 21, 2015 at 04:20:25PM +0000, Andri Yngvason wrote:
> Quoting Ahmed S. Darwish (2015-01-20 21:45:37)
> > From: Ahmed S. Darwish <ahmed.darwish@valeo.com>
> > 
> > Replace most of the can interface's state and error counters
> > handling with the new can-dev can_change_state() mechanism.
> > 
> > Suggested-by: Andri Yngvason <andri.yngvason@marel.com>
> > Signed-off-by: Ahmed S. Darwish <ahmed.darwish@valeo.com>
> > ---
> >  drivers/net/can/usb/kvaser_usb.c | 114 +++++++++++++++++++--------------------
> >  1 file changed, 55 insertions(+), 59 deletions(-)
> > 
> > diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
> > index 971c5f9..0386d3f 100644
> > --- a/drivers/net/can/usb/kvaser_usb.c
> > +++ b/drivers/net/can/usb/kvaser_usb.c
> > @@ -620,40 +620,43 @@ static void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv)
> >  }
> >  
> >  static void kvaser_usb_rx_error_update_can_state(struct kvaser_usb_net_priv *priv,
> > -                                                const struct kvaser_usb_error_summary *es)
> > +                                                const struct kvaser_usb_error_summary *es,
> > +                                                struct can_frame *cf)
> >  {
> >         struct net_device_stats *stats;
> > -       enum can_state new_state;
> > -
> > -       stats = &priv->netdev->stats;
> > -       new_state = priv->can.state;
> > +       enum can_state cur_state, new_state, tx_state, rx_state;
> >  
> >         netdev_dbg(priv->netdev, "Error status: 0x%02x\n", es->status);
> >  
> > -       if (es->status & M16C_STATE_BUS_OFF) {
> > -               priv->can.can_stats.bus_off++;
> > +       stats = &priv->netdev->stats;
> > +       new_state = cur_state = priv->can.state;
> > +
> > +       if (es->status & M16C_STATE_BUS_OFF)
> >                 new_state = CAN_STATE_BUS_OFF;
> > -       } else if (es->status & M16C_STATE_BUS_PASSIVE) {
> > -               if (priv->can.state != CAN_STATE_ERROR_PASSIVE)
> > -                       priv->can.can_stats.error_passive++;
> > +       else if (es->status & M16C_STATE_BUS_PASSIVE)
> >                 new_state = CAN_STATE_ERROR_PASSIVE;
> > -       }
> >  
> >         if (es->status == M16C_STATE_BUS_ERROR) {
> > -               if ((priv->can.state < CAN_STATE_ERROR_WARNING) &&
> > -                   ((es->txerr >= 96) || (es->rxerr >= 96))) {
> > -                       priv->can.can_stats.error_warning++;
> > +               if ((cur_state < CAN_STATE_ERROR_WARNING) &&
> > +                   ((es->txerr >= 96) || (es->rxerr >= 96)))
> >                         new_state = CAN_STATE_ERROR_WARNING;
> > -               } else if (priv->can.state > CAN_STATE_ERROR_ACTIVE) {
> > +               else if (cur_state > CAN_STATE_ERROR_ACTIVE)
> >                         new_state = CAN_STATE_ERROR_ACTIVE;
> > -               }
> >         }
> >  
> >         if (!es->status)
> >                 new_state = CAN_STATE_ERROR_ACTIVE;
> >  
> > +       if (new_state != cur_state) {
> > +               tx_state = (es->txerr >= es->rxerr) ? new_state : 0;
> > +               rx_state = (es->txerr <= es->rxerr) ? new_state : 0;
> > +
> > +               can_change_state(priv->netdev, cf, tx_state, rx_state);
>
> This (below) is redundant. It doesn't harm but at this point can_change_state
> has set priv->can.state to new_state.
>
> > +               new_state = priv->can.state;
> > +       }
> > +

Correct; I will remove it.

> >         if (priv->can.restart_ms &&
> > -           (priv->can.state >= CAN_STATE_BUS_OFF) &&
> > +           (cur_state >= CAN_STATE_BUS_OFF) &&
> >             (new_state < CAN_STATE_BUS_OFF)) {
> >                 priv->can.can_stats.restarts++;
> >         }
> > @@ -665,18 +668,17 @@ static void kvaser_usb_rx_error_update_can_state(struct kvaser_usb_net_priv *pri
> >  
> >         priv->bec.txerr = es->txerr;
> >         priv->bec.rxerr = es->rxerr;
> > -       priv->can.state = new_state;
> >  }
> >  
> >  static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
> >                                 const struct kvaser_msg *msg)
> >  {
> > -       struct can_frame *cf;
> > +       struct can_frame *cf, tmp_cf = { .can_id = CAN_ERR_FLAG, .can_dlc = CAN_ERR_DLC };
> >         struct sk_buff *skb;
> >         struct net_device_stats *stats;
> >         struct kvaser_usb_net_priv *priv;
> >         struct kvaser_usb_error_summary es = { };
> > -       enum can_state old_state;
> > +       enum can_state old_state, new_state;
> >  
> >         switch (msg->id) {
> >         case CMD_CAN_ERROR_EVENT:
> > @@ -721,60 +723,54 @@ static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
> >         }
> >  
> >         /* Update all of the can interface's state and error counters before
> > -        * trying any skb allocation that can actually fail with -ENOMEM.
> > +        * trying any memory allocation that can actually fail with -ENOMEM.
> > +        *
> > +        * We send a temporary stack-allocated error can frame to
> > +        * can_change_state() for the very same reason.
> > +        *
> > +        * TODO: Split can_change_state() responsibility between updating the
> > +        * can interface's state and counters, and the setting up of can error
> > +        * frame ID and data to userspace. Remove stack allocation afterwards.
> >          */
> >         old_state = priv->can.state;
> > -       kvaser_usb_rx_error_update_can_state(priv, &es);
> > +       kvaser_usb_rx_error_update_can_state(priv, &es, &tmp_cf);
> > +       new_state = priv->can.state;
> >  
> >         skb = alloc_can_err_skb(priv->netdev, &cf);
> >         if (!skb) {
> >                 stats->rx_dropped++;
> >                 return;
> >         }
> > +       memcpy(cf, &tmp_cf, sizeof(*cf));
> >  
> > -       if (es.status & M16C_STATE_BUS_OFF) {
> > -               cf->can_id |= CAN_ERR_BUSOFF;
> > -
> > -               if (!priv->can.restart_ms)
> > -                       kvaser_usb_simple_msg_async(priv, CMD_STOP_CHIP);
> > -               netif_carrier_off(priv->netdev);
> > -       } else if (es.status & M16C_STATE_BUS_PASSIVE) {
> > -               if (old_state != CAN_STATE_ERROR_PASSIVE) {
> > -                       cf->can_id |= CAN_ERR_CRTL;
> > -
> > -                       if (es.txerr || es.rxerr)
> > -                               cf->data[1] = (es.txerr > es.rxerr)
> > -                                               ? CAN_ERR_CRTL_TX_PASSIVE
> > -                                               : CAN_ERR_CRTL_RX_PASSIVE;
> > -                       else
> > -                               cf->data[1] = CAN_ERR_CRTL_TX_PASSIVE |
> > -                                             CAN_ERR_CRTL_RX_PASSIVE;
> > +       if (new_state != old_state) {
> > +               if (es.status & M16C_STATE_BUS_OFF) {
> > +                       if (!priv->can.restart_ms)
> > +                               kvaser_usb_simple_msg_async(priv, CMD_STOP_CHIP);
> > +                       netif_carrier_off(priv->netdev);
> > +               }
> > +
>
> This block [below] is wrong. The usage of PROT_ACTIVE is based on a misunderstanding.
> It's used in some drivers to signify back-to-error-active but its original
> meaning is something completely different, AFAIK.
> This is handled in can_change_state() using a new CTRL message; namely:
> CAN_ERR_CTRL_ACTIVE. The newest version of can-utils is up to date with this.
>
> > +               if (es.status == M16C_STATE_BUS_ERROR) {
> > +                       if ((old_state >= CAN_STATE_ERROR_WARNING) ||
> > +                           (es.txerr < 96 && es.rxerr < 96)) {
> > +                               if (old_state > CAN_STATE_ERROR_ACTIVE) {
> > +                                       cf->can_id |= CAN_ERR_PROT;
> > +                                       cf->data[2] = CAN_ERR_PROT_ACTIVE;
> > +                               }
> > +                       }
> >                 }

So I would just make the new_state equals CAN_STATE_ERROR_ACTIVE,
and then can_change_state() will do the right thing? Excellent!!
This means the entire block above can be removed ;-)

[ On another note, the block's if conditions above are faulty and
  fixed in patch #3. This patch (#2) used can_change_state()
  without changing any of that faulty logic to ease any future
  bisection. ]

> > -       }
> >  
> > -       if (es.status == M16C_STATE_BUS_ERROR) {
> > -               if ((old_state < CAN_STATE_ERROR_WARNING) &&
> > -                   ((es.txerr >= 96) || (es.rxerr >= 96))) {
> > -                       cf->can_id |= CAN_ERR_CRTL;
> > -                       cf->data[1] = (es.txerr > es.rxerr)
> > -                                       ? CAN_ERR_CRTL_TX_WARNING
> > -                                       : CAN_ERR_CRTL_RX_WARNING;
> > -               } else if (old_state > CAN_STATE_ERROR_ACTIVE) {
>
> This is also redundant, and wrong:
>
> > +               if (!es.status) {
> >                         cf->can_id |= CAN_ERR_PROT;
> >                         cf->data[2] = CAN_ERR_PROT_ACTIVE;
> >                 }
> > -       }

As in the above; extra code to be removed, yay! ;-)

> >  
> > -       if (!es.status) {
> > -               cf->can_id |= CAN_ERR_PROT;
> > -               cf->data[2] = CAN_ERR_PROT_ACTIVE;
> > -       }
> > -
> > -       if (priv->can.restart_ms &&
> > -           (old_state >= CAN_STATE_BUS_OFF) &&
> > -           (priv->can.state < CAN_STATE_BUS_OFF)) {
> > -               cf->can_id |= CAN_ERR_RESTARTED;
> > -               netif_carrier_on(priv->netdev);
> > +               if (priv->can.restart_ms &&
> > +                   (old_state >= CAN_STATE_BUS_OFF) &&
> > +                   (new_state < CAN_STATE_BUS_OFF)) {
> > +                       cf->can_id |= CAN_ERR_RESTARTED;
> > +                       netif_carrier_on(priv->netdev);
> > +               }
> >         }
> >  
> >         if (es.error_factor) {
> > -- 
> > 1.9.1
> 
> Looking over the patch again, I've noticed that there
> are a few things that are not quite right.
> 

The state-handlig code has become much simpler since your
reveiw and Kleine-Budde's one. Thanks a lot for all the effort.

Regards,
Darwish

  parent reply index

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-23 15:46 [PATCH] can: kvaser_usb: Don't free packets when tight on URBs Ahmed S. Darwish
2014-12-23 15:53 ` [PATCH] can: kvaser_usb: Add support for the Usbcan-II family Ahmed S. Darwish
2014-12-24 12:36   ` Olivier Sobrie
2014-12-24 15:04     ` Ahmed S. Darwish
2014-12-28 21:51       ` Olivier Sobrie
2014-12-30 15:33         ` Ahmed S. Darwish
2014-12-31 12:13           ` Olivier Sobrie
2014-12-24 12:31 ` [PATCH] can: kvaser_usb: Don't free packets when tight on URBs Olivier Sobrie
2014-12-24 15:52   ` Ahmed S. Darwish
2014-12-24 23:56 ` [PATCH v2 1/4] " Ahmed S. Darwish
2014-12-24 23:59   ` [PATCH v2 2/4] can: kvaser_usb: Reset all URB tx contexts upon channel close Ahmed S. Darwish
2014-12-25  0:02     ` [PATCH v2 3/4] can: kvaser_usb: Don't send a RESET_CHIP for non-existing channels Ahmed S. Darwish
2014-12-25  0:04       ` [PATCH v2 4/4] can: kvaser_usb: Add support for the Usbcan-II family Ahmed S. Darwish
2014-12-28 21:54       ` [PATCH v2 3/4] can: kvaser_usb: Don't send a RESET_CHIP for non-existing channels Olivier Sobrie
2014-12-25  2:50   ` [PATCH v2 1/4] can: kvaser_usb: Don't free packets when tight on URBs Greg KH
2014-12-25  9:38     ` Ahmed S. Darwish
2014-12-28 21:52   ` Olivier Sobrie
2015-01-01 21:59 ` [PATCH] " Stephen Hemminger
2015-01-03 14:34   ` Ahmed S. Darwish
2015-01-05 17:49 ` [PATCH v3 1/4] " Ahmed S. Darwish
2015-01-05 17:52   ` [PATCH v3 2/4] can: kvaser_usb: Reset all URB tx contexts upon channel close Ahmed S. Darwish
2015-01-05 17:57     ` [PATCH v3 3/4] can: kvaser_usb: Don't send a RESET_CHIP for non-existing channels Ahmed S. Darwish
2015-01-05 18:31       ` [PATCH v3 4/4] can: kvaser_usb: Add support for the Usbcan-II family Ahmed S. Darwish
2015-01-08 11:53         ` Marc Kleine-Budde
2015-01-08 15:19           ` Ahmed S. Darwish
2015-01-12 11:51             ` Marc Kleine-Budde
2015-01-12 12:26               ` Ahmed S. Darwish
2015-01-12 12:34                 ` Marc Kleine-Budde
2015-01-09  3:06           ` Ahmed S. Darwish
2015-01-09 14:05             ` Marc Kleine-Budde
2015-01-08  9:59   ` [PATCH v3 1/4] can: kvaser_usb: Don't free packets when tight on URBs Marc Kleine-Budde
2015-01-11 20:05 ` [PATCH v4 00/04] can: Introduce support for Kvaser USBCAN-II devices Ahmed S. Darwish
2015-01-11 20:11   ` [PATCH v4 01/04] can: kvaser_usb: Don't dereference skb after a netif_rx() devices Ahmed S. Darwish
2015-01-11 20:15     ` [PATCH v4 2/4] can: kvaser_usb: Update error counters before exiting on OOM Ahmed S. Darwish
2015-01-11 20:36       ` [PATCH v4 3/4] can: kvaser_usb: Add support for the Usbcan-II family Ahmed S. Darwish
2015-01-11 20:45         ` [PATCH v4 4/4] can: kvaser_usb: Retry first bulk transfer on -ETIMEDOUT Ahmed S. Darwish
2015-01-11 20:51           ` Marc Kleine-Budde
2015-01-12 10:14             ` Ahmed S. Darwish
2015-01-12 10:25               ` Marc Kleine-Budde
2015-01-12 13:33               ` Olivier Sobrie
2015-01-12 13:50                 ` Ahmed S. Darwish
2015-01-12 11:20         ` [PATCH v4 3/4] can: kvaser_usb: Add support for the Usbcan-II family Ahmed S. Darwish
2015-01-12 11:43         ` Marc Kleine-Budde
2015-01-12 12:07           ` Ahmed S. Darwish
2015-01-12 12:36             ` Ahmed S. Darwish
2015-01-12 13:53         ` Olivier Sobrie
2015-01-18 20:12           ` Ahmed S. Darwish
2015-01-18 20:13             ` Marc Kleine-Budde
2015-01-12 11:09       ` [PATCH v4 2/4] can: kvaser_usb: Update error counters before exiting on OOM Marc Kleine-Budde
2015-01-12 20:36         ` Ahmed S. Darwish
2015-01-16 14:39           ` Marc Kleine-Budde
2015-01-11 20:49     ` [PATCH v4 01/04] can: kvaser_usb: Don't dereference skb after a netif_rx() Ahmed S. Darwish
2015-01-12 11:05       ` Marc Kleine-Budde
2015-01-20 21:44 ` [PATCH v5 1/5] can: kvaser_usb: Update net interface state before exiting on OOM Ahmed S. Darwish
2015-01-20 21:45   ` [PATCH v5 2/5] can: kvaser_usb: Consolidate and unify state change handling Ahmed S. Darwish
2015-01-20 21:47     ` [PATCH v5 3/5] can: kvaser_usb: Fix state handling upon BUS_ERROR events Ahmed S. Darwish
2015-01-20 21:48       ` [PATCH v5 4/5] can: kvaser_usb: Retry the first bulk transfer on -ETIMEDOUT Ahmed S. Darwish
2015-01-20 21:50         ` [PATCH v5 5/5] can: kvaser_usb: Add support for the USBcan-II family Ahmed S. Darwish
2015-01-21 12:24         ` [PATCH v5 4/5] can: kvaser_usb: Retry the first bulk transfer on -ETIMEDOUT Sergei Shtylyov
2015-01-25 11:59           ` Ahmed S. Darwish
2015-01-21 10:33     ` [PATCH v5 2/5] can: kvaser_usb: Consolidate and unify state change handling Andri Yngvason
2015-01-21 10:44       ` Marc Kleine-Budde
2015-01-21 11:00         ` Andri Yngvason
2015-01-21 11:53       ` Wolfgang Grandegger
2015-01-21 14:43         ` Ahmed S. Darwish
2015-01-21 15:00           ` Andri Yngvason
2015-01-21 15:36             ` Ahmed S. Darwish
2015-01-21 16:13               ` Wolfgang Grandegger
2015-01-23  6:07                 ` Ahmed S. Darwish
2015-01-23 10:32                   ` Andri Yngvason
2015-01-25  2:43                     ` Ahmed S. Darwish
2015-01-26 10:21                       ` Andri Yngvason
2015-01-21 16:37               ` Andri Yngvason
2015-01-21 16:20     ` Andri Yngvason
2015-01-21 22:59       ` Marc Kleine-Budde
2015-01-22 10:14         ` Andri Yngvason
2015-01-25  2:49           ` Ahmed S. Darwish
2015-01-25  3:21       ` Ahmed S. Darwish [this message]
2015-01-26  5:17 ` [PATCH v6 0/7] can: kvaser_usb: Leaf bugfixes and USBCan-II support Ahmed S. Darwish
2015-01-26  5:20   ` [PATCH v6 1/7] can: kvaser_usb: Do not sleep in atomic context Ahmed S. Darwish
2015-01-26  5:22     ` [PATCH v6 2/7] can: kvaser_usb: Send correct context to URB completion Ahmed S. Darwish
2015-01-26  5:24       ` [PATCH v6 3/7] can: kvaser_usb: Retry the first bulk transfer on -ETIMEDOUT Ahmed S. Darwish
2015-01-26  5:25         ` [PATCH v6 4/7] can: kvaser_usb: Fix state handling upon BUS_ERROR events Ahmed S. Darwish
2015-01-26  5:27           ` [PATCH v6 5/7] can: kvaser_usb: Update interface state before exiting on OOM Ahmed S. Darwish
2015-01-26  5:29             ` [PATCH v6 6/7] can: kvaser_usb: Consolidate and unify state change handling Ahmed S. Darwish
2015-01-26  5:33               ` [PATCH v6 7/7] can: kvaser_usb: Add support for the USBcan-II family Ahmed S. Darwish
2015-01-26 10:34                 ` Andri Yngvason
2015-01-26 10:26               ` [PATCH v6 6/7] can: kvaser_usb: Consolidate and unify state change handling Andri Yngvason
2015-01-26 10:28             ` [PATCH v6 5/7] can: kvaser_usb: Update interface state before exiting on OOM Andri Yngvason
2015-01-26 10:50               ` Marc Kleine-Budde
2015-01-26 10:52                 ` Andri Yngvason
2015-01-26 10:53                   ` Marc Kleine-Budde
2015-01-26  9:55   ` [PATCH v6 0/7] can: kvaser_usb: Leaf bugfixes and USBCan-II support Marc Kleine-Budde
2015-01-26 10:07   ` Marc Kleine-Budde
2015-01-26 10:56     ` Marc Kleine-Budde

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