[PATCH] Avoid reset work on watchdog timer function during error recovery

[gpiccoli@linux.vnet.ibm.com (Guilherme G. Piccoli)]

On 04/07/2016 10:11 AM, Christoph Hellwig wrote:
> On Wed, Apr 06, 2016@05:30:35PM -0300, Guilherme G. Piccoli wrote:
>>   	/*
>>   	 * Skip controllers currently under reset.
>> +	 * Also, skip controllers going through PCI error recovery.
>>   	 */
>>   	if (!work_pending(&dev->reset_work) && !work_busy(&dev->reset_work) &&
>>   	    ((csts & NVME_CSTS_CFS) ||
>> -	     (dev->subsystem && (csts & NVME_CSTS_NSSRO)))) {
>> +	    (dev->subsystem && (csts & NVME_CSTS_NSSRO))) &&
>> +	    !pci_channel_offline(to_pci_dev(dev->dev))) {
>>   		if (queue_work(nvme_workq, &dev->reset_work)) {
>>   			dev_warn(dev->dev,
>>   				"Failed status: 0x%x, reset controller.\n",
>
> This looks correct to me, but the condition is getting basically
> unreadable.  Can you factor it out into a little helper returns a
> boolean value if we should reset or not, and document each condition,
> e.g. something like the function below, just with proper comments:
>
> static bool nvme_should_reset(struct nvme_dev *dev)
> {
> 	u32 csts = readl(dev->bar + NVME_REG_CSTS);
>
> 	if (!(csts & NVME_CSTS_CFS) &&
> 	    !((dev->subsystem && (csts & NVME_CSTS_NSSRO))))
> 		return false;
>
> 	if (work_pending(&dev->reset_work))
> 		return false;
> 	if (work_busy(&dev->reset_work))
> 		return false;
> 	if (pci_channel_offline(to_pci_dev(dev->dev))
> 		return false;
>
> 	return true;
> }
>

Heheh agreed, very good suggestion indeed. I found myself struggling to 
understand this huge condition line. I'll improve it following your 
suggestion, thanks.

Cheers,


Guilherme