linux-kernel - Re: [Bugfix 3/3] eata: Enhance eata driver to support PCI device hot-removal

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Message-ID: <55F68654.4070709@linux.intel.com>
Date:	Mon, 14 Sep 2015 16:33:24 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	"Ballabio, Dario" <dario.ballabio@....com>,
	Hannes Reinecke <hare@...e.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Arthur Marsh <arthur.marsh@...ernode.on.net>,
	"James E.J. Bottomley" <JBottomley@...n.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>
Subject: Re: [Bugfix 3/3] eata: Enhance eata driver to support PCI device
 hot-removal

On 2015/9/14 16:31, Ballabio, Dario wrote:
> Agreed, It does not make sense to have  this driver converted to a hot plug api.
Thanks, got the point:)
Originally i thought user may trigger PCI device hot-removal by sysfs
interfaces and there's comment mentioning that eata driver breaks
PCI hotplug, so I tried to solve it. If it's no real use, we may
just drop the third patch.
Thanks!
Gerry

> 
> Cheers,
> 
> 
> 
> ***************************************
> Ph.D. Dario Ballabio
> Principal Field Support Specialist, EMC EMEA 
> Mobile phone: +393487978851
> 
> 
> 
> -----Original Message-----
> From: Hannes Reinecke [mailto:hare@...e.de] 
> Sent: Monday, September 14, 2015 10:21 AM
> To: Jiang Liu; Thomas Gleixner; Bjorn Helgaas; Arthur Marsh; Ballabio, Dario; James E.J. Bottomley
> Cc: linux-kernel@...r.kernel.org; linux-pci@...r.kernel.org; linux-scsi@...r.kernel.org; x86@...nel.org
> Subject: Re: [Bugfix 3/3] eata: Enhance eata driver to support PCI device hot-removal
> 
> On 09/14/2015 05:08 AM, Jiang Liu wrote:
>> Due to having no hardware for testing, this is just a sample code to 
>> support PCI device hot-removal. It just passing compilation, no any 
>> tests.
>>
>> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
>> ---
>>  drivers/scsi/eata.c |   26 ++++++++++++++++++++++++++
>>  1 file changed, 26 insertions(+)
>>
>> diff --git a/drivers/scsi/eata.c b/drivers/scsi/eata.c index 
>> b92e6856f909..f3bd7cbf260e 100644
>> --- a/drivers/scsi/eata.c
>> +++ b/drivers/scsi/eata.c
>> @@ -1474,6 +1474,21 @@ static unsigned int port_probe(unsigned long 
>> port_base,  #ifdef CONFIG_PCI  static int eata2x_pci_device_count;
>>  
>> +/* TODO: need help here to shutdown the scsi host and release 
>> +resources */ static void port_remove(unsigned int id, resource_size_t port_base,
>> +			struct pci_dev *pdev)
>> +{
>> +	struct Scsi_Host *shost = sh[id];
>> +
>> +	/* TODO: stop scsi device */
>> +	scsi_unregister(shost);
>> +	/* TODO: clean up resources allocated by port_detect() */
>> +	clear_bit(id, eata_board_bitmap);
>> +	free_irq(shost->irq, &sha[id]);
>> +	release_region(port_base, REGION_SIZE);
>> +	ida_simple_remove(&eata_ida, id);
>> +}
>> +
>>  static int eata2x_pci_probe(struct pci_dev *dev, const struct 
>> pci_device_id *id)  {
>>  	int i, ret = -ENXIO;
>> @@ -1521,6 +1536,16 @@ out_error:
>>  	return ret;
>>  }
>>  
>> +static void eata2x_pci_remove(struct pci_dev *pdev) {
>> +	int id = (int)(long)dev_get_drvdata(&pdev->dev);
>> +	resource_size_t port_base;
>> +
>> +	port_base = pci_resource_start(pdev, 0) + PCI_BASE_ADDRESS_0;
>> +	port_remove(id, port_base, pdev);
>> +	pci_disable_device(pdev);
>> +}
>> +
>>  static struct pci_device_id eata2x_tbl[] = {
>>  	{ PCI_DEVICE_CLASS(PCI_CLASS_STORAGE_SCSI << 8, PCI_ANY_ID) },
>>  	{ },
>> @@ -1531,6 +1556,7 @@ static struct pci_driver eata2x_pci_driver = {
>>  	.name		= "eata",
>>  	.id_table	= eata2x_tbl,
>>  	.probe		= eata2x_pci_probe,
>> +	.remove		= eata2x_pci_remove,
>>  };
>>  
>>  static int eata2x_probe_pci_devices(struct scsi_host_template *tpnt)
>>
> Welll ... if you don't have hardware (and I strongly hope you refer to 'hardware able to do hotplugging', not 'hardware for the eata driver'
> ...) why add the code at all?
> Chances are no-one will ever need eata PCI hotplug; SCSI parallel typically isn't very good at hotplugging, so throwing in PCI hotplug will only confuse matters more.
> Plus due to the sheer mechanics involved here I find it very unlikely anyone will be using it in real life.
> 
> Cheers,
> 
> Hannes
> 
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