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From: "Ahmed S. Darwish" <darwish.07@gmail.com>
To: Olivier Sobrie <olivier@sobrie.be>,
	Oliver Hartkopp <socketcan@hartkopp.net>,
	Wolfgang Grandegger <wg@grandegger.com>,
	Marc Kleine-Budde <mkl@pengutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Linux-CAN <linux-can@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Linux-stable <stable@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH v2 2/4] can: kvaser_usb: Reset all URB tx contexts upon channel close
Date: Thu, 25 Dec 2014 01:59:54 +0200
Message-ID: <20141224235954.GA24302@vivalin-002> (raw)
In-Reply-To: <20141224235644.GA3778@vivalin-002>

From: Ahmed S. Darwish <ahmed.darwish@valeo.com>

Flooding the Kvaser CAN to USB dongle with multiple reads and
writes in very high frequency (*), closing the CAN channel while
all the transmissions are on (#), opening the device again (@),
then sending a small number of packets would make the driver
enter an almost infinite loop of:

[....]
[15959.853988] kvaser_usb 4-3:1.0 can0: cannot find free context
[15959.853990] kvaser_usb 4-3:1.0 can0: cannot find free context
[15959.853991] kvaser_usb 4-3:1.0 can0: cannot find free context
[15959.853993] kvaser_usb 4-3:1.0 can0: cannot find free context
[15959.853994] kvaser_usb 4-3:1.0 can0: cannot find free context
[15959.853995] kvaser_usb 4-3:1.0 can0: cannot find free context
[....]

_dragging the whole system down_ in the process due to the
excessive logging output.

Initially, this has caused random panics in the kernel due to a
buggy error recovery path.  That got fixed in an earlier commit.(%)
This patch aims at solving the root cause. -->

16 tx URBs and contexts are allocated per CAN channel per USB
device. Such URBs are protected by:

a) A simple atomic counter, up to a value of MAX_TX_URBS (16)
b) A flag in each URB context, stating if it's free
c) The fact that ndo_start_xmit calls are themselves protected
   by the networking layers higher above

After grabbing one of the tx URBs, if the driver noticed that all
of them are now taken, it stops the netif transmission queue.
Such queue is worken up again only if an acknowedgment was received
from the firmware on one of our earlier-sent frames.

Meanwhile, upon channel close (#), the driver sends a CMD_STOP_CHIP
to the firmware, effectively closing all further communication.  In
the high traffic case, the atomic counter remains at MAX_TX_URBS,
and all the URB contexts remain marked as active.  While opening
the channel again (@), it cannot send any further frames since no
more free tx URB contexts are available.

Reset all tx URB contexts upon CAN channel close.

(*) 50 parallel instances of `cangen0 -g 0 -ix`
(#) `ifconfig can0 down`
(@) `ifconfig can0 up`
(%) "can: kvaser_usb: Don't free packets when tight on URBs"

Signed-off-by: Ahmed S. Darwish <ahmed.darwish@valeo.com>
---
 drivers/net/can/usb/kvaser_usb.c | 3 +++
 1 file changed, 3 insertions(+)

 (Marc, Greg, this also should be added to -stable?)

diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
index 6479a2b..598e251 100644
--- a/drivers/net/can/usb/kvaser_usb.c
+++ b/drivers/net/can/usb/kvaser_usb.c
@@ -1246,6 +1246,9 @@ static int kvaser_usb_close(struct net_device *netdev)
 	if (err)
 		netdev_warn(netdev, "Cannot stop device, error %d\n", err);
 
+	/* reset tx contexts */
+	kvaser_usb_unlink_tx_urbs(priv);
+
 	priv->can.state = CAN_STATE_STOPPED;
 	close_candev(priv->netdev);
 

  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   ` Ahmed S. Darwish [this message]
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
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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