[BUG] atmel: spi: scheduling while atomic

[Jiří Prchal]

So shouldn't we (you) apply it to mainstream?

Dne 11.3.2014 10:54, Yang, Wenyou napsal(a):
>
>> -----Original Message-----
>> From: Jiří Prchal [mailto:jiri.prchal at aksignal.cz]
>> Sent: Tuesday, March 11, 2014 5:46 PM
>> To: Yang, Wenyou; Rabin Vincent; Alexandre Belloni
>> Cc: Ferre, Nicolas; linux-arm-kernel at lists.infradead.org;
>> sboyd at codeaurora.org
>> Subject: Re: [BUG] atmel: spi: scheduling while atomic
>>
>> Hi,
>> patch applied, it helps.
>> Is this final solution?
>> Thanks
>
> Thank for your feedback.
> There isn't a better solution so far.
>
> Best Regards,
> Wenyou Yang
>
>>
>> Dne 10.3.2014 10:08, Yang, Wenyou napsal(a):
>>>
>>>
>>>> -----Original Message-----
>>>> From: Jiří Prchal [mailto:jiri.prchal at aksignal.cz]
>>>> Sent: Monday, March 10, 2014 4:12 PM
>>>> To: Rabin Vincent; Alexandre Belloni; Yang, Wenyou
>>>> Cc: Ferre, Nicolas; linux-arm-kernel at lists.infradead.org;
>>>> sboyd at codeaurora.org
>>>> Subject: Re: [BUG] atmel: spi: scheduling while atomic
>>>>
>>>> Hi all,
>>>> at first: warning is on all spi devices.
>>>> at second: its with CONFIG_PREEMPT=y, without (# CONFIG_PREEMPT_RCU
>>>> is not set) is OK, but I wonder if this config will be fast enough
>>>> for our usage (nearly RT)?
>>>>
>>>>
>>>> Dne 8.3.2014 01:41, Rabin Vincent napsal(a):
>>>>> 2014-03-07 23:58 GMT+01:00 Alexandre Belloni
>>>>> <alexandre.belloni at free-electrons.com>:
>>>>>> On 05/03/2014 at 07:56:04 +0100, Jiří Prchal wrote :
>>>>>>> [    0.902343] BUG: scheduling while atomic: spi0/383/0x00000002
>>>>>>> [    0.906250] Modules linked in:
>>>>>>> [    0.906250] CPU: 0 PID: 383 Comm: spi0 Not tainted 3.14.0-
>>>> rc4_cpm9g25+ #1
>>>>>>> [    0.906250] [<c000d9f4>] (unwind_backtrace) from [<c000bdc0>]
>>>> (show_stack+0x10/0x14)
>>>>>>> [    0.906250] [<c000bdc0>] (show_stack) from [<c003a224>]
>>>> (__schedule_bug+0x48/0x60)
>>>>>>> [    0.906250] [<c003a224>] (__schedule_bug) from [<c0390294>]
>>>> (__schedule+0x60/0x484)
>>>>>>> [    0.906250] [<c0390294>] (__schedule) from [<c038feac>]
>>>> (schedule_timeout+0x17c/0x1ac)
>>>>>>> [    0.906250] [<c038feac>] (schedule_timeout) from [<c039111c>]
>>>> (wait_for_common+0x10c/0x1f0)
>>>>>>> [    0.906250] [<c039111c>] (wait_for_common) from [<c0249228>]
>>>> (atmel_spi_transfer_one_message+0x71c/0xa48)
>>>>>>> [    0.906250] [<c0249228>] (atmel_spi_transfer_one_message) from
>>>> [<c0246624>] (spi_pump_messages+0x210/0x238)
>>>>>>> [    0.906250] [<c0246624>] (spi_pump_messages) from [<c00343d0>]
>>>> (kthread_worker_fn+0x15c/0x1b4)
>>>>>>> [    0.906250] [<c00343d0>] (kthread_worker_fn) from [<c0034534>]
>>>> (kthread+0xb8/0xcc)
>>>>>>> [    0.906250] [<c0034534>] (kthread) from [<c0009510>]
>>>> (ret_from_fork+0x14/0x24)
>>>>>>> [    0.906250] at25 spi0.0: 128 KByte at25 eeprom, pagesize 512
>>>>>>
>>>>>> Actually, I'm not quite sure how spi_pump_messages can be called
>>>>>> from
>>>> an
>>>>>> atomic context.
>>>>>
>>>>> spi_pump_messages() is not called from atomic context.  Rather,
>>>>> atmel_spi_transfer_one_message() does a spin_lock_irqsave() (via
>>>>> atmel_spi_lock()) and then calls atmel_spi_one_transfer(), which
>>>>> calls wait_for_completion_timeout().  That's why schedule is being
>>>>> called from atomic context.  This was introduced by 8090d6d1a4 ("spi:
>> atmel:
>>>>> Refactor spi-atmel to use SPI framework queue"). I think you should
>>>>> see the warning with CONFIG_PREEMPT=y.
>>>>>
>>>
>>> Thanks a lot for the report and analysis.
>>>
>>> --->8--------
>>>   From ba2dd7aee12cb09b9ef159251859443e1b055669 Mon Sep 17 00:00:00
>>> 2001
>>> From: Wenyou Yang <wenyou.yang at atmel.com>
>>> Date: Mon, 10 Mar 2014 16:44:33 +0800
>>> Subject: [PATCH] spi: atmel: fix BUG: scheduling while atomic with
>>>    CONFIG_PREEMPT=y
>>>
>>> introduced by 8090d6d1a415d3ae1a7208995decfab8f60f4f36
>>> ("spi: atmel: Refactor spi-atmel to use SPI framework queue")
>>>
>>> Signed-off-by: Wenyou Yang <wenyou.yang at atmel.com>
>>> ---
>>>    drivers/spi/spi-atmel.c |    4 ++++
>>>    1 file changed, 4 insertions(+)
>>>
>>> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index
>>> b0842f7..e05c3f2 100644
>>> --- a/drivers/spi/spi-atmel.c
>>> +++ b/drivers/spi/spi-atmel.c
>>> @@ -1130,8 +1130,12 @@ static int atmel_spi_one_transfer(struct
>> spi_master *master,
>>>    			atmel_spi_next_xfer_pio(master, xfer);
>>>    		}
>>>
>>> +		atmel_spi_unlock(as);
>>> +
>>>    		ret = wait_for_completion_timeout(&as->xfer_completion,
>>>    							SPI_DMA_TIMEOUT);
>>> +		atmel_spi_lock(as);
>>> +
>>>    		if (WARN_ON(ret == 0)) {
>>>    			dev_err(&spi->dev,
>>>    				"spi trasfer timeout, err %d\n", ret);
>>>