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

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Message-ID: <55F6837A.5020807@suse.de>
Date:	Mon, 14 Sep 2015 10:21:14 +0200
From:	Hannes Reinecke <hare@...e.de>
To:	Jiang Liu <jiang.liu@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Arthur Marsh <arthur.marsh@...ernode.on.net>,
	Dario Ballabio <ballabio_dario@....com>,
	"James E.J. Bottomley" <JBottomley@...n.com>
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
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@...e.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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