[PATCH] NVMe: Add a character device for each nvme device

[Matthew Wilcox]

On Fri, Jul 27, 2012 at 10:44:18AM -0600, Keith Busch wrote:
> Registers a character device for the nvme module and creates character
> files as /dev/nvmeN for each nvme device probed, where N is the device
> instance. The character devices support nvme admin ioctl commands so
> that nvme devices without namespaces can be managed.

I don't see a problem here, but I'm no expert at sysfs / character devices.
Alan, Greg, anyone else see any problems with how this character device is
created / destroyed?

> 
> Signed-off-by: Keith Busch <keith.busch at intel.com>
> ---
>  drivers/block/nvme.c |   55 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 54 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
> index 7bcd882..8a16ac8 100644
> --- a/drivers/block/nvme.c
> +++ b/drivers/block/nvme.c
> @@ -20,6 +20,7 @@
>  #include <linux/bio.h>
>  #include <linux/bitops.h>
>  #include <linux/blkdev.h>
> +#include <linux/cdev.h>
>  #include <linux/delay.h>
>  #include <linux/errno.h>
>  #include <linux/fs.h>
> @@ -45,6 +46,7 @@
>  #define SQ_SIZE(depth)		(depth * sizeof(struct nvme_command))
>  #define CQ_SIZE(depth)		(depth * sizeof(struct nvme_completion))
>  #define NVME_MINORS 64
> +#define NVME_MAX_DEVS 1024
>  #define NVME_IO_TIMEOUT	(5 * HZ)
>  #define ADMIN_TIMEOUT	(60 * HZ)
>  
> @@ -54,9 +56,13 @@ module_param(nvme_major, int, 0);
>  static int use_threaded_interrupts;
>  module_param(use_threaded_interrupts, int, 0);
>  
> +static int nvme_char_major;
> +module_param(nvme_char_major, int, 0);
> +
>  static DEFINE_SPINLOCK(dev_list_lock);
>  static LIST_HEAD(dev_list);
>  static struct task_struct *nvme_thread;
> +static struct class *nvme_char_cl;
>  
>  /*
>   * Represents an NVM Express device.  Each nvme_dev is a PCI function.
> @@ -1222,6 +1228,35 @@ static const struct block_device_operations nvme_fops = {
>  	.compat_ioctl	= nvme_ioctl,
>  };
>  
> +static long nvme_char_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
> +{
> +	struct nvme_dev *dev;
> +	int instance = iminor(f->f_dentry->d_inode);
> +
> +	spin_lock(&dev_list_lock);
> +	list_for_each_entry(dev, &dev_list, node) {
> +		if (dev->instance == instance)
> +			break;
> +	}
> +	spin_unlock(&dev_list_lock);
> +
> +	if (&dev->node == &dev_list)
> +		return -ENOTTY;
> +	
> +	switch (cmd) {
> +	case NVME_IOCTL_ADMIN_CMD:
> +		return nvme_user_admin_cmd(dev, (void __user *)arg);
> +	default:
> +		return -ENOTTY;
> +	}
> +}
> +
> +static const struct file_operations nvme_char_fops = {
> +	.owner		= THIS_MODULE,
> +	.unlocked_ioctl	= nvme_char_ioctl,
> +	.compat_ioctl	= nvme_char_ioctl,
> +};
> +
>  static void nvme_timeout_ios(struct nvme_queue *nvmeq)
>  {
>  	int depth = nvmeq->q_depth - 1;
> @@ -1632,6 +1667,8 @@ static int __devinit nvme_probe(struct pci_dev *pdev,
>  	if (result)
>  		goto delete;
>  
> +	device_create(nvme_char_cl, NULL, MKDEV(nvme_char_major, dev->instance),
> +						NULL, "nvme%d", dev->instance);
>  	return 0;
>  
>   delete:
> @@ -1660,6 +1697,7 @@ static void __devexit nvme_remove(struct pci_dev *pdev)
>  {
>  	struct nvme_dev *dev = pci_get_drvdata(pdev);
>  	nvme_dev_remove(dev);
> +	device_destroy(nvme_char_cl, MKDEV(nvme_char_major, dev->instance));
>  	pci_disable_msix(pdev);
>  	iounmap(dev->bar);
>  	nvme_release_instance(dev);
> @@ -1721,11 +1759,24 @@ static int __init nvme_init(void)
>  	else if (result > 0)
>  	    nvme_major = result;
>  
> +	result = __register_chrdev(nvme_char_major, 0, NVME_MAX_DEVS, "nvme",
> +							&nvme_char_fops);
> +	if (result < 0)
> +		goto unregister_blkdev;
> +	else if (result > 0)
> +		nvme_char_major = result;
> +	nvme_char_cl = class_create(THIS_MODULE, "nvme");
> +	if (!nvme_char_cl)
> +		goto unregister_chrdev;
>  	result = pci_register_driver(&nvme_driver);
>  	if (result)
> -		goto unregister_blkdev;
> +		goto destroy_class;
>  	return 0;
>  
> + destroy_class:
> +	class_destroy(nvme_char_cl);
> + unregister_chrdev:
> +	__unregister_chrdev(nvme_char_major, 0, NVME_MAX_DEVS, "nvme");
>   unregister_blkdev:
>  	unregister_blkdev(nvme_major, "nvme");
>   kill_kthread:
> @@ -1736,6 +1787,8 @@ static int __init nvme_init(void)
>  static void __exit nvme_exit(void)
>  {
>  	pci_unregister_driver(&nvme_driver);
> +	class_destroy(nvme_char_cl);
> +	__unregister_chrdev(nvme_char_major, 0, NVME_MAX_DEVS, "nvme");
>  	unregister_blkdev(nvme_major, "nvme");
>  	kthread_stop(nvme_thread);
>  }
> -- 
> 1.7.0.4
> 
> 
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