[v4,15/25] nvdimm/ocxl: Register a character device for userspace to interact with
diff mbox series

Message ID 20200327071202.2159885-16-alastair@d-silva.org
State New
Headers show
Series
  • Add support for OpenCAPI Persistent Memory devices
Related show

Commit Message

Alastair D'Silva March 27, 2020, 7:11 a.m. UTC
This patch introduces a character device (/dev/ocxlpmemX) which further
patches will use to interact with userspace, such as error logs,
controller stats and card debug functionality.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/nvdimm/ocxl/main.c     | 117 ++++++++++++++++++++++++++++++++-
 drivers/nvdimm/ocxl/ocxlpmem.h |   2 +
 2 files changed, 117 insertions(+), 2 deletions(-)

Comments

Dan Williams April 2, 2020, 12:27 a.m. UTC | #1
On Sun, Mar 29, 2020 at 10:53 PM Alastair D'Silva <alastair@d-silva.org> wrote:
>
> This patch introduces a character device (/dev/ocxlpmemX) which further
> patches will use to interact with userspace, such as error logs,
> controller stats and card debug functionality.

This was asked earlier, but I'll reiterate, I do not see what
justifies an ocxlpmemX private device ABI vs routing through the
existing generic character ndbusX and nmemX character devices.

>
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>  drivers/nvdimm/ocxl/main.c     | 117 ++++++++++++++++++++++++++++++++-
>  drivers/nvdimm/ocxl/ocxlpmem.h |   2 +
>  2 files changed, 117 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvdimm/ocxl/main.c b/drivers/nvdimm/ocxl/main.c
> index 8db573036423..9b85fcd3f1c9 100644
> --- a/drivers/nvdimm/ocxl/main.c
> +++ b/drivers/nvdimm/ocxl/main.c
> @@ -10,6 +10,7 @@
>  #include <misc/ocxl.h>
>  #include <linux/delay.h>
>  #include <linux/ndctl.h>
> +#include <linux/fs.h>
>  #include <linux/mm_types.h>
>  #include <linux/memory_hotplug.h>
>  #include "ocxlpmem.h"
> @@ -356,6 +357,67 @@ static int ocxlpmem_register(struct ocxlpmem *ocxlpmem)
>         return device_register(&ocxlpmem->dev);
>  }
>
> +static void ocxlpmem_put(struct ocxlpmem *ocxlpmem)
> +{
> +       put_device(&ocxlpmem->dev);
> +}
> +
> +static struct ocxlpmem *ocxlpmem_get(struct ocxlpmem *ocxlpmem)
> +{
> +       return (!get_device(&ocxlpmem->dev)) ? NULL : ocxlpmem;
> +}
> +
> +static struct ocxlpmem *find_and_get_ocxlpmem(dev_t devno)
> +{
> +       struct ocxlpmem *ocxlpmem;
> +       int minor = MINOR(devno);
> +
> +       mutex_lock(&minors_idr_lock);
> +       ocxlpmem = idr_find(&minors_idr, minor);
> +       if (ocxlpmem)
> +               ocxlpmem_get(ocxlpmem);
> +       mutex_unlock(&minors_idr_lock);
> +
> +       return ocxlpmem;
> +}
> +
> +static int file_open(struct inode *inode, struct file *file)
> +{
> +       struct ocxlpmem *ocxlpmem;
> +
> +       ocxlpmem = find_and_get_ocxlpmem(inode->i_rdev);
> +       if (!ocxlpmem)
> +               return -ENODEV;
> +
> +       file->private_data = ocxlpmem;
> +       return 0;
> +}
> +
> +static int file_release(struct inode *inode, struct file *file)
> +{
> +       struct ocxlpmem *ocxlpmem = file->private_data;
> +
> +       ocxlpmem_put(ocxlpmem);
> +       return 0;
> +}
> +
> +static const struct file_operations fops = {
> +       .owner          = THIS_MODULE,
> +       .open           = file_open,
> +       .release        = file_release,
> +};
> +
> +/**
> + * create_cdev() - Create the chardev in /dev for the device
> + * @ocxlpmem: the SCM metadata
> + * Return: 0 on success, negative on failure
> + */
> +static int create_cdev(struct ocxlpmem *ocxlpmem)
> +{
> +       cdev_init(&ocxlpmem->cdev, &fops);
> +       return cdev_add(&ocxlpmem->cdev, ocxlpmem->dev.devt, 1);
> +}
> +
>  /**
>   * ocxlpmem_remove() - Free an OpenCAPI persistent memory device
>   * @pdev: the PCI device information struct
> @@ -376,6 +438,13 @@ static void remove(struct pci_dev *pdev)
>                 if (ocxlpmem->nvdimm_bus)
>                         nvdimm_bus_unregister(ocxlpmem->nvdimm_bus);
>
> +               /*
> +                * Remove the cdev early to prevent a race against userspace
> +                * via the char dev
> +                */
> +               if (ocxlpmem->cdev.owner)
> +                       cdev_del(&ocxlpmem->cdev);
> +
>                 device_unregister(&ocxlpmem->dev);
>         }
>  }
> @@ -527,11 +596,18 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>                 goto err;
>         }
>
> -       if (setup_command_metadata(ocxlpmem)) {
> +       rc = setup_command_metadata(ocxlpmem);
> +       if (rc) {
>                 dev_err(&pdev->dev, "Could not read command metadata\n");
>                 goto err;
>         }
>
> +       rc = create_cdev(ocxlpmem);
> +       if (rc) {
> +               dev_err(&pdev->dev, "Could not create character device\n");
> +               goto err;
> +       }
> +
>         elapsed = 0;
>         timeout = ocxlpmem->readiness_timeout +
>                   ocxlpmem->memory_available_timeout;
> @@ -599,6 +675,36 @@ static struct pci_driver pci_driver = {
>         .shutdown = remove,
>  };
>
> +static int file_init(void)
> +{
> +       int rc;
> +
> +       rc = alloc_chrdev_region(&ocxlpmem_dev, 0, NUM_MINORS, "ocxlpmem");
> +       if (rc) {
> +               idr_destroy(&minors_idr);
> +               pr_err("Unable to allocate OpenCAPI persistent memory major number: %d\n",
> +                      rc);
> +               return rc;
> +       }
> +
> +       ocxlpmem_class = class_create(THIS_MODULE, "ocxlpmem");
> +       if (IS_ERR(ocxlpmem_class)) {
> +               idr_destroy(&minors_idr);
> +               pr_err("Unable to create ocxlpmem class\n");
> +               unregister_chrdev_region(ocxlpmem_dev, NUM_MINORS);
> +               return PTR_ERR(ocxlpmem_class);
> +       }
> +
> +       return 0;
> +}
> +
> +static void file_exit(void)
> +{
> +       class_destroy(ocxlpmem_class);
> +       unregister_chrdev_region(ocxlpmem_dev, NUM_MINORS);
> +       idr_destroy(&minors_idr);
> +}
> +
>  static int __init ocxlpmem_init(void)
>  {
>         int rc;
> @@ -606,16 +712,23 @@ static int __init ocxlpmem_init(void)
>         mutex_init(&minors_idr_lock);
>         idr_init(&minors_idr);
>
> -       rc = pci_register_driver(&pci_driver);
> +       rc = file_init();
>         if (rc)
>                 return rc;
>
> +       rc = pci_register_driver(&pci_driver);
> +       if (rc) {
> +               file_exit();
> +               return rc;
> +       }
> +
>         return 0;
>  }
>
>  static void ocxlpmem_exit(void)
>  {
>         pci_unregister_driver(&pci_driver);
> +       file_exit();
>  }
>
>  module_init(ocxlpmem_init);
> diff --git a/drivers/nvdimm/ocxl/ocxlpmem.h b/drivers/nvdimm/ocxl/ocxlpmem.h
> index b72b3f909fc3..ee3bd651f254 100644
> --- a/drivers/nvdimm/ocxl/ocxlpmem.h
> +++ b/drivers/nvdimm/ocxl/ocxlpmem.h
> @@ -2,6 +2,7 @@
>  // Copyright 2020 IBM Corp.
>
>  #include <linux/pci.h>
> +#include <linux/cdev.h>
>  #include <misc/ocxl.h>
>  #include <linux/libnvdimm.h>
>  #include <linux/mm.h>
> @@ -103,6 +104,7 @@ struct command_metadata {
>  struct ocxlpmem {
>         struct device dev;
>         struct pci_dev *pdev;
> +       struct cdev cdev;
>         struct ocxl_fn *ocxl_fn;
>         struct nd_interleave_set nd_set;
>         struct nvdimm_bus_descriptor bus_desc;
> --
> 2.24.1
>

Patch
diff mbox series

diff --git a/drivers/nvdimm/ocxl/main.c b/drivers/nvdimm/ocxl/main.c
index 8db573036423..9b85fcd3f1c9 100644
--- a/drivers/nvdimm/ocxl/main.c
+++ b/drivers/nvdimm/ocxl/main.c
@@ -10,6 +10,7 @@ 
 #include <misc/ocxl.h>
 #include <linux/delay.h>
 #include <linux/ndctl.h>
+#include <linux/fs.h>
 #include <linux/mm_types.h>
 #include <linux/memory_hotplug.h>
 #include "ocxlpmem.h"
@@ -356,6 +357,67 @@  static int ocxlpmem_register(struct ocxlpmem *ocxlpmem)
 	return device_register(&ocxlpmem->dev);
 }
 
+static void ocxlpmem_put(struct ocxlpmem *ocxlpmem)
+{
+	put_device(&ocxlpmem->dev);
+}
+
+static struct ocxlpmem *ocxlpmem_get(struct ocxlpmem *ocxlpmem)
+{
+	return (!get_device(&ocxlpmem->dev)) ? NULL : ocxlpmem;
+}
+
+static struct ocxlpmem *find_and_get_ocxlpmem(dev_t devno)
+{
+	struct ocxlpmem *ocxlpmem;
+	int minor = MINOR(devno);
+
+	mutex_lock(&minors_idr_lock);
+	ocxlpmem = idr_find(&minors_idr, minor);
+	if (ocxlpmem)
+		ocxlpmem_get(ocxlpmem);
+	mutex_unlock(&minors_idr_lock);
+
+	return ocxlpmem;
+}
+
+static int file_open(struct inode *inode, struct file *file)
+{
+	struct ocxlpmem *ocxlpmem;
+
+	ocxlpmem = find_and_get_ocxlpmem(inode->i_rdev);
+	if (!ocxlpmem)
+		return -ENODEV;
+
+	file->private_data = ocxlpmem;
+	return 0;
+}
+
+static int file_release(struct inode *inode, struct file *file)
+{
+	struct ocxlpmem *ocxlpmem = file->private_data;
+
+	ocxlpmem_put(ocxlpmem);
+	return 0;
+}
+
+static const struct file_operations fops = {
+	.owner		= THIS_MODULE,
+	.open		= file_open,
+	.release	= file_release,
+};
+
+/**
+ * create_cdev() - Create the chardev in /dev for the device
+ * @ocxlpmem: the SCM metadata
+ * Return: 0 on success, negative on failure
+ */
+static int create_cdev(struct ocxlpmem *ocxlpmem)
+{
+	cdev_init(&ocxlpmem->cdev, &fops);
+	return cdev_add(&ocxlpmem->cdev, ocxlpmem->dev.devt, 1);
+}
+
 /**
  * ocxlpmem_remove() - Free an OpenCAPI persistent memory device
  * @pdev: the PCI device information struct
@@ -376,6 +438,13 @@  static void remove(struct pci_dev *pdev)
 		if (ocxlpmem->nvdimm_bus)
 			nvdimm_bus_unregister(ocxlpmem->nvdimm_bus);
 
+		/*
+		 * Remove the cdev early to prevent a race against userspace
+		 * via the char dev
+		 */
+		if (ocxlpmem->cdev.owner)
+			cdev_del(&ocxlpmem->cdev);
+
 		device_unregister(&ocxlpmem->dev);
 	}
 }
@@ -527,11 +596,18 @@  static int probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		goto err;
 	}
 
-	if (setup_command_metadata(ocxlpmem)) {
+	rc = setup_command_metadata(ocxlpmem);
+	if (rc) {
 		dev_err(&pdev->dev, "Could not read command metadata\n");
 		goto err;
 	}
 
+	rc = create_cdev(ocxlpmem);
+	if (rc) {
+		dev_err(&pdev->dev, "Could not create character device\n");
+		goto err;
+	}
+
 	elapsed = 0;
 	timeout = ocxlpmem->readiness_timeout +
 		  ocxlpmem->memory_available_timeout;
@@ -599,6 +675,36 @@  static struct pci_driver pci_driver = {
 	.shutdown = remove,
 };
 
+static int file_init(void)
+{
+	int rc;
+
+	rc = alloc_chrdev_region(&ocxlpmem_dev, 0, NUM_MINORS, "ocxlpmem");
+	if (rc) {
+		idr_destroy(&minors_idr);
+		pr_err("Unable to allocate OpenCAPI persistent memory major number: %d\n",
+		       rc);
+		return rc;
+	}
+
+	ocxlpmem_class = class_create(THIS_MODULE, "ocxlpmem");
+	if (IS_ERR(ocxlpmem_class)) {
+		idr_destroy(&minors_idr);
+		pr_err("Unable to create ocxlpmem class\n");
+		unregister_chrdev_region(ocxlpmem_dev, NUM_MINORS);
+		return PTR_ERR(ocxlpmem_class);
+	}
+
+	return 0;
+}
+
+static void file_exit(void)
+{
+	class_destroy(ocxlpmem_class);
+	unregister_chrdev_region(ocxlpmem_dev, NUM_MINORS);
+	idr_destroy(&minors_idr);
+}
+
 static int __init ocxlpmem_init(void)
 {
 	int rc;
@@ -606,16 +712,23 @@  static int __init ocxlpmem_init(void)
 	mutex_init(&minors_idr_lock);
 	idr_init(&minors_idr);
 
-	rc = pci_register_driver(&pci_driver);
+	rc = file_init();
 	if (rc)
 		return rc;
 
+	rc = pci_register_driver(&pci_driver);
+	if (rc) {
+		file_exit();
+		return rc;
+	}
+
 	return 0;
 }
 
 static void ocxlpmem_exit(void)
 {
 	pci_unregister_driver(&pci_driver);
+	file_exit();
 }
 
 module_init(ocxlpmem_init);
diff --git a/drivers/nvdimm/ocxl/ocxlpmem.h b/drivers/nvdimm/ocxl/ocxlpmem.h
index b72b3f909fc3..ee3bd651f254 100644
--- a/drivers/nvdimm/ocxl/ocxlpmem.h
+++ b/drivers/nvdimm/ocxl/ocxlpmem.h
@@ -2,6 +2,7 @@ 
 // Copyright 2020 IBM Corp.
 
 #include <linux/pci.h>
+#include <linux/cdev.h>
 #include <misc/ocxl.h>
 #include <linux/libnvdimm.h>
 #include <linux/mm.h>
@@ -103,6 +104,7 @@  struct command_metadata {
 struct ocxlpmem {
 	struct device dev;
 	struct pci_dev *pdev;
+	struct cdev cdev;
 	struct ocxl_fn *ocxl_fn;
 	struct nd_interleave_set nd_set;
 	struct nvdimm_bus_descriptor bus_desc;