Re: [PATCH 5/5] can: flexcan: flexcan_close(): change order if commands to properly shut down the controller

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 11/19/20 10:46 AM, Joakim Zhang wrote:
> 
>> -----Original Message-----
>> From: Marc Kleine-Budde <mkl@pengutronix.de>
>> Sent: 2020年11月19日 16:53
>> To: linux-can@vger.kernel.org
>> Cc: Joakim Zhang <qiangqing.zhang@nxp.com>; kernel@pengutronix.de; Marc
>> Kleine-Budde <mkl@pengutronix.de>
>> Subject: [PATCH 5/5] can: flexcan: flexcan_close(): change order if commands
>> to properly shut down the controller
>>
>> There haven been reports, that the flexcan_close() soradically hangs during
>> simultanious ifdown, sending of CAN messages and probably open CAN bus:
>>
>> | (__schedule) from [<808bbd34>] (schedule+0x90/0xb8)
>> | (schedule) from [<808bf274>] (schedule_timeout+0x1f8/0x24c)
>> | (schedule_timeout) from [<8016be44>] (msleep+0x18/0x1c)
>> | (msleep) from [<80746a64>] (napi_disable+0x60/0x70)
>> | (napi_disable) from [<8052fdd0>] (flexcan_close+0x2c/0x140)
>> | (flexcan_close) from [<80744930>] (__dev_close_many+0xb8/0xd8)
>> | (__dev_close_many) from [<8074db9c>] (__dev_change_flags+0xd0/0x1a0)
>> | (__dev_change_flags) from [<8074dc84>] (dev_change_flags+0x18/0x48)
>> | (dev_change_flags) from [<80760c24>] (do_setlink+0x44c/0x7b4)
>> | (do_setlink) from [<80761560>] (rtnl_newlink+0x374/0x68c)
>>
>> I was unable to reproduce the issue, but a cleanup of the flexcan close
>> sequence has probably fixed the problem at the reporting user.
>>
>> This patch changes the sequence in flexcan_close() to:
>> - stop the TX queue
>> - disable the interrupts on the chip level and wait via free_irq()
>>   synchronously for the interrupt handler to finish
>> - disable RX offload, which disables synchronously NAPI
>> - disable the flexcan on the chip level
>> - free RX offload
>> - disable the transceiver
>> - close the CAN device
>> - disable the clocks
>>
>> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
>> ---
>>  drivers/net/can/flexcan.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c index
>> 0fb768dee99f..002e93f2b249 100644
>> --- a/drivers/net/can/flexcan.c
>> +++ b/drivers/net/can/flexcan.c
>> @@ -1789,15 +1789,16 @@ static int flexcan_close(struct net_device *dev)
>>  	struct flexcan_priv *priv = netdev_priv(dev);
>>
>>  	netif_stop_queue(dev);
>> +	flexcan_chip_interrupts_disable(dev);
>> +	free_irq(dev->irq, dev);
>>  	can_rx_offload_disable(&priv->offload);
>>  	flexcan_chip_stop_disable_on_error(dev);
>>  	flexcan_chip_interrupts_disable(dev);
> 
> Hi Marc,
> 
> Is it a special treatment? flexcan_chip_interrupts_disable called twice?

Thanks for catching this. It's a mistake, will fix.

> 	flexcan_chip_interrupts_disable(dev);
> 	free_irq(dev->irq, dev);
>   	can_rx_offload_disable(&priv->offload);
>   	flexcan_chip_stop_disable_on_error(dev);
>   	flexcan_chip_interrupts_disable(dev);

Thanks for the review,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |


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