linux-kernel - Re: [PATCH] ahci: unregister acpi notify handler when a ZPODD is unbound

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Message-ID: <53687C1E.2020001@intel.com>
Date:	Tue, 06 May 2014 14:07:26 +0800
From:	Aaron Lu <aaron.lu@...el.com>
To:	Levente Kurusa <levex@...ux.com>, Tejun Heo <tj@...nel.org>
CC:	LKML <linux-kernel@...r.kernel.org>,
	Linux ATA/IDE <linux-ide@...r.kernel.org>,
	Joe Thomas <Joe.Thomas@...hill.com>
Subject: Re: [PATCH] ahci: unregister acpi notify handler when a ZPODD is
 unbound

On 05/06/2014 02:02 PM, Levente Kurusa wrote:
> Hi,
> 
> On 05/06/2014 05:16 AM, Aaron Lu wrote:
>> On 05/01/2014 12:04 AM, Levente Kurusa wrote:
>>> When a ZPODD device is unbound via sysfs, the acpi notify handler
>>> is not removed. This causes panics as observed in Bug #74601. The
>>
>> Ah...too bad, I forgot to consider this situation, thanks for tracking
>> this.
>>
>>> panic only happens when the wake happens from outside the kernel
>>> (i.e. inserting media or pressing a button). Implement a new
>>> ahci_remove_one function which causes zpodd_exit to be called for all
>>> ZPODD devices on the unbound PCI device.
>>>
>>> Signed-off-by: Levente Kurusa <levex@...ux.com>
>>> ---
>>>
>>> Hi,
>>>
>>> I am not sure if the loop below is correct. Maybe there is a better
>>> solution to loop through all the devices which might use ZPODD?
>>
>> I didn't find a proper place either. For hotplug, we did the zpodd_exit
>> at ata_scsi_handle_link_detach. But for host controller pci device
>> removal, we used scsi_remove_host in ata_port_detach and there is no
>> place to add the zpodd_exit for a to-be-removed scsi device...
>>
>> Looks like we can only iterate the ata devices and call zpodd_exit
>> explicitly for them if they are zpodd devices. Instead of adding a new
>> remove callback, what about just embed that into the ata_port_detach
>> like the following example?
> 
> Yes, this makes more sense as this doesn't tinker with exports and such...
> However this will throw unused variable compiler warnings if we add the
> required #ifdefs... Maybe a new function? ata_zpodd_detach_port?

I think we can omit the #ifdefs as the loop is not called frequently and
thus doesn't cost much. We already have stubs for zpodd_dev_enabled and
zpodd_exit.

Thanks,
Aaron

> 
>>
>>
>> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
>> index 943cc8b83e59..43652da6fea6 100644
>> --- a/drivers/ata/libata-core.c
>> +++ b/drivers/ata/libata-core.c
>> @@ -6314,6 +6314,8 @@ int ata_host_activate(struct ata_host *host, int irq,
>>  static void ata_port_detach(struct ata_port *ap)
>>  {
>>  	unsigned long flags;
>> +	struct ata_link *link;
>> +	struct ata_device *dev;
>>  
>>  	if (!ap->ops->error_handler)
>>  		goto skip_eh;
>> @@ -6333,6 +6335,13 @@ static void ata_port_detach(struct ata_port *ap)
>>  	cancel_delayed_work_sync(&ap->hotplug_task);
>>  
>>   skip_eh:
>> +	/* clean up zpodd related stuffs on port removal */
>> +	ata_for_each_link(link, ap, HOST_FIRST) {
>> +		ata_for_each_dev(dev, link, ALL) {
>> +			if (zpodd_dev_enabled(dev))
>> +				zpodd_exit(dev);
>> +		}
>> +	}
>>  	if (ap->pmp_link) {
>>  		int i;
>>  		for (i = 0; i < SATA_PMP_MAX_PORTS; i++)
> 

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