linux-kernel - Re: [PATCH 3/3] dmaengine: idxd: Do not call DMX TX callbacks during workqueue disable

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Message-ID: <d9a6e626-96fb-0593-3410-3bed6c3fb3d0@intel.com>
Date:   Fri, 2 Dec 2022 13:51:11 -0800
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     "Yu, Fenghua" <fenghua.yu@...el.com>,
        "Jiang, Dave" <dave.jiang@...el.com>,
        "vkoul@...nel.org" <vkoul@...nel.org>,
        "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] dmaengine: idxd: Do not call DMX TX callbacks during
 workqueue disable

Hi Fenghua,

On 12/2/2022 1:12 PM, Yu, Fenghua wrote:

...

>> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c index
>> b4d7bb923a40..2ac71a34fa34 100644
>> --- a/drivers/dma/idxd/device.c
>> +++ b/drivers/dma/idxd/device.c
>> @@ -1156,6 +1156,7 @@ int idxd_device_load_config(struct idxd_device *idxd)
>>
>>  static void idxd_flush_pending_descs(struct idxd_irq_entry *ie)  {
>> +	struct dma_async_tx_descriptor *tx;
> 
> Nitpicking. It's better to move this line to below:
> 
>>  	struct idxd_desc *desc, *itr;
>>  	struct llist_node *head;
>>  	LIST_HEAD(flist);
>> @@ -1175,6 +1176,15 @@ static void idxd_flush_pending_descs(struct
>> idxd_irq_entry *ie)
>>  	list_for_each_entry_safe(desc, itr, &flist, list) {
> 
> here?
> +	struct dma_async_tx_descriptor *tx;
> 

Will do.

>>  		list_del(&desc->list);
>>  		ctype = desc->completion->status ?
>> IDXD_COMPLETE_NORMAL : IDXD_COMPLETE_ABORT;
>> +		/*
>> +		 * wq is being disabled. Any remaining descriptors are
>> +		 * likely to be stuck and can be dropped. callback could
>> +		 * point to code that is no longer accessible, for example
>> +		 * if dmatest module has been unloaded.
>> +		 */
>> +		tx = &desc->txd;
>> +		tx->callback = NULL;
>> +		tx->callback_result = NULL;
>>  		idxd_dma_complete_txd(desc, ctype, true);
>>  	}
>>  }
>> --
>> 2.34.1
> 
> Reviewed-by: Fenghua Yu <fenghua.yu@...el.com>

Thank you very much.

Reinette