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From: Andrew Donnellan <ajd@linux.ibm.com>
To: "Alastair D'Silva" <alastair@au1.ibm.com>, alastair@d-silva.org
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	"Paul Mackerras" <paulus@samba.org>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Frederic Barrat" <fbarrat@linux.ibm.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Mauro Carvalho Chehab" <mchehab+samsung@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	"Rob Herring" <robh@kernel.org>,
	"Anton Blanchard" <anton@ozlabs.org>,
	"Krzysztof Kozlowski" <krzk@kernel.org>,
	"Mahesh Salgaonkar" <mahesh@linux.vnet.ibm.com>,
	"Madhavan Srinivasan" <maddy@linux.vnet.ibm.com>,
	"Cédric Le Goater" <clg@kaod.org>,
	"Anju T Sudhakar" <anju@linux.vnet.ibm.com>,
	"Hari Bathini" <hbathini@linux.ibm.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Greg Kurz" <groug@kaod.org>,
	"Nicholas Piggin" <npiggin@gmail.com>,
	"Masahiro Yamada" <yamada.masahiro@socionext.com>,
	"Alexey Kardashevskiy" <aik@ozlabs.ru>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 16/27] powerpc/powernv/pmem: Register a character device for userspace to interact with
Date: Mon, 2 Mar 2020 16:34:23 +1100	[thread overview]
Message-ID: <1e980dc7-109a-d96f-1329-1c38918e2bba@linux.ibm.com> (raw)
In-Reply-To: <20200221032720.33893-17-alastair@au1.ibm.com>

On 21/2/20 2:27 pm, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> This patch introduces a character device (/dev/ocxl-scmX) which further
> patches will use to interact with userspace.

As with the comments on other patches in this series, this commit 
message is lacking in explanation. What's the purpose of this device?

> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   arch/powerpc/platforms/powernv/pmem/ocxl.c    | 116 +++++++++++++++++-
>   .../platforms/powernv/pmem/ocxl_internal.h    |   2 +
>   2 files changed, 116 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/pmem/ocxl.c b/arch/powerpc/platforms/powernv/pmem/ocxl.c
> index b8bd7e703b19..63109a870d2c 100644
> --- a/arch/powerpc/platforms/powernv/pmem/ocxl.c
> +++ b/arch/powerpc/platforms/powernv/pmem/ocxl.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 "ocxl_internal.h"
> @@ -339,6 +340,9 @@ static void free_ocxlpmem(struct ocxlpmem *ocxlpmem)
>   
>   	free_minor(ocxlpmem);
>   
> +	if (ocxlpmem->cdev.owner)
> +		cdev_del(&ocxlpmem->cdev);
> +
>   	if (ocxlpmem->metadata_addr)
>   		devm_memunmap(&ocxlpmem->dev, ocxlpmem->metadata_addr);
>   
> @@ -396,6 +400,70 @@ 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) ? NULL : ocxlpmem;
> +}
> +
> +static struct ocxlpmem *find_and_get_ocxlpmem(dev_t devno)
> +{
> +	struct ocxlpmem *ocxlpmem;
> +	int minor = MINOR(devno);
> +	/*
> +	 * We don't declare an RCU critical section here, as our AFU
> +	 * is protected by a re0ference counter on the device. By the time the
> +	 * minor number of a device is removed from the idr, the ref count of
> +	 * the device is already at 0, so no user API will access that AFU and
> +	 * this function can't return it.
> +	 */
> +	ocxlpmem = idr_find(&minors_idr, minor);
> +	if (ocxlpmem)
> +		ocxlpmem_get(ocxlpmem);
> +	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
> @@ -572,6 +640,11 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>   		goto err;
>   	}
>   
> +	if (create_cdev(ocxlpmem)) {
> +		dev_err(&pdev->dev, "Could not create character device\n");
> +		goto err;
> +	}
> +
>   	elapsed = 0;
>   	timeout = ocxlpmem->readiness_timeout + ocxlpmem->memory_available_timeout;
>   	while (!is_usable(ocxlpmem, false)) {
> @@ -613,20 +686,59 @@ static struct pci_driver pci_driver = {
>   	.shutdown = ocxlpmem_remove,
>   };
>   
> +static int file_init(void)
> +{
> +	int rc;
> +
> +	mutex_init(&minors_idr_lock);
> +	idr_init(&minors_idr);
> +
> +	rc = alloc_chrdev_region(&ocxlpmem_dev, 0, NUM_MINORS, "ocxl-pmem");

If the driver is going to be called "ocxlpmem" can we standardise on 
that without the extra hyphen?

> +	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, "ocxl-pmem");
> +	if (IS_ERR(ocxlpmem_class)) {
> +		idr_destroy(&minors_idr);
> +		pr_err("Unable to create ocxl-pmem 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 = 0;
> +	int rc;
>   
> -	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);
-- 
Andrew Donnellan              OzLabs, ADL Canberra
ajd@linux.ibm.com             IBM Australia Limited
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  reply	other threads:[~2020-03-02  5:34 UTC|newest]

Thread overview: 130+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-21  3:26 [PATCH v3 00/27] Add support for OpenCAPI Persistent Memory devices Alastair D'Silva
2020-02-21  3:26 ` [PATCH v3 01/27] powerpc: Add OPAL calls for LPC memory alloc/release Alastair D'Silva
2020-02-24  5:49   ` Andrew Donnellan
2020-02-24  5:50     ` Alastair D'Silva
2020-02-21  3:26 ` [PATCH v3 02/27] mm/memory_hotplug: Allow check_hotplug_memory_addressable to be called from drivers Alastair D'Silva
2020-02-21  7:03   ` Andrew Donnellan
2020-02-21  3:26 ` [PATCH v3 03/27] powerpc: Map & release OpenCAPI LPC memory Alastair D'Silva
2020-02-24  2:51   ` Andrew Donnellan
2020-02-24  5:49     ` Andrew Donnellan
2020-02-25 10:02   ` Frederic Barrat
2020-02-26  0:19     ` Alastair D'Silva
2020-03-03  6:10   ` Andrew Donnellan
2020-03-04  5:33     ` Alastair D'Silva
2020-02-21  3:26 ` [PATCH v3 04/27] ocxl: Remove unnecessary externs Alastair D'Silva
2020-02-21  6:06   ` Andrew Donnellan
2020-02-25 13:23   ` Frederic Barrat
2020-02-26  8:14   ` Baoquan He
2020-02-26  8:26     ` Alastair D'Silva
2020-02-26  9:01       ` Greg Kurz
2020-02-26 14:15         ` 'Baoquan He'
2020-02-26 14:20           ` Greg Kurz
2020-02-26 14:54             ` 'Baoquan He'
2020-02-21  3:26 ` [PATCH v3 05/27] ocxl: Address kernel doc errors & warnings Alastair D'Silva
2020-02-24  2:11   ` Andrew Donnellan
2020-02-21  3:26 ` [PATCH v3 06/27] ocxl: Tally up the LPC memory on a link & allow it to be mapped Alastair D'Silva
2020-02-24  5:25   ` Andrew Donnellan
2020-02-24  5:36     ` Alastair D'Silva
2020-02-25 16:30   ` Frederic Barrat
2020-02-26  0:29     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 07/27] ocxl: Add functions to map/unmap LPC memory Alastair D'Silva
2020-02-24  6:02   ` Andrew Donnellan
2020-02-24  6:08     ` Alastair D'Silva
2020-02-25 17:01   ` Frederic Barrat
2020-02-21  3:27 ` [PATCH v3 08/27] ocxl: Emit a log message showing how much LPC memory was detected Alastair D'Silva
2020-02-24  6:06   ` Andrew Donnellan
2020-02-24  6:10     ` Alastair D'Silva
2020-02-24  6:13       ` Andrew Donnellan
2020-02-25 17:03   ` Frederic Barrat
2020-02-21  3:27 ` [PATCH v3 09/27] ocxl: Save the device serial number in ocxl_fn Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 10/27] powerpc: Add driver for OpenCAPI Persistent Memory Alastair D'Silva
2020-02-26  5:07   ` Andrew Donnellan
2020-02-26  5:49     ` Alastair D'Silva
2020-02-27 20:44   ` Frederic Barrat
2020-02-28  0:54     ` Alastair D'Silva
2020-02-28 18:32   ` Frederic Barrat
2020-02-21  3:27 ` [PATCH v3 11/27] powerpc: Enable the OpenCAPI Persistent Memory driver for powernv_defconfig Alastair D'Silva
2020-02-25  3:01   ` Andrew Donnellan
2020-02-21  3:27 ` [PATCH v3 12/27] powerpc/powernv/pmem: Add register addresses & status values to the header Alastair D'Silva
2020-02-27  5:08   ` Andrew Donnellan
2020-02-27  5:16     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 13/27] powerpc/powernv/pmem: Read the capability registers & wait for device ready Alastair D'Silva
2020-02-27  3:54   ` Andrew Donnellan
2020-02-27  3:58     ` Alastair D'Silva
2020-03-02 17:51   ` Frederic Barrat
2020-03-04  4:15     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 14/27] powerpc/powernv/pmem: Add support for Admin commands Alastair D'Silva
2020-02-27  8:22   ` Andrew Donnellan
2020-02-27  8:27     ` Andrew Donnellan
2020-02-27 23:54       ` Alastair D'Silva
2020-02-27 23:51     ` Alastair D'Silva
2020-02-27 17:01   ` Dan Williams
2020-02-27 23:57     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 15/27] powerpc/powernv/pmem: Add support for near storage commands Alastair D'Silva
2020-02-27  8:30   ` Andrew Donnellan
2020-02-27 23:56     ` Alastair D'Silva
2020-02-27 17:02   ` Dan Williams
2020-03-02 17:58   ` Frederic Barrat
2020-03-02 18:42     ` Dan Williams
2020-03-04  4:42       ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 16/27] powerpc/powernv/pmem: Register a character device for userspace to interact with Alastair D'Silva
2020-03-02  5:34   ` Andrew Donnellan [this message]
2020-03-02  6:05     ` Alastair D'Silva
2020-03-03  9:28   ` Frederic Barrat
2020-03-05  3:38     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 17/27] powerpc/powernv/pmem: Implement the Read Error Log command Alastair D'Silva
2020-03-03 10:36   ` Frederic Barrat
2020-03-05  4:31     ` Alastair D'Silva
2020-03-05  9:33       ` Frederic Barrat
2020-03-04  5:58   ` Andrew Donnellan
2020-02-21  3:27 ` [PATCH v3 18/27] powerpc/powernv/pmem: Add controller dump IOCTLs Alastair D'Silva
2020-03-03 18:04   ` Frederic Barrat
2020-03-05 23:37     ` Alastair D'Silva
2020-03-04  6:53   ` Andrew Donnellan
2020-03-06  3:34     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 19/27] powerpc/powernv/pmem: Add an IOCTL to report controller statistics Alastair D'Silva
2020-03-04  9:25   ` Frederic Barrat
2020-03-12  0:15     ` Alastair D'Silva
2020-03-05  0:46   ` Andrew Donnellan
2020-03-12  4:47     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 20/27] powerpc/powernv/pmem: Forward events to userspace Alastair D'Silva
2020-03-03  7:02   ` Andrew Donnellan
2020-03-04  5:48     ` Alastair D'Silva
2020-03-04 11:00   ` Frederic Barrat
2020-03-11  3:32     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 21/27] powerpc/powernv/pmem: Add an IOCTL to request controller health & perf data Alastair D'Silva
2020-02-28  6:12   ` Andrew Donnellan
2020-03-02  5:40     ` Alastair D'Silva
2020-03-04 11:06     ` Frederic Barrat
2020-03-11  3:38       ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 22/27] powerpc/powernv/pmem: Implement the heartbeat command Alastair D'Silva
2020-02-28  6:20   ` Andrew Donnellan
2020-03-04 14:25   ` Frederic Barrat
2020-02-21  3:27 ` [PATCH v3 23/27] powerpc/powernv/pmem: Add debug IOCTLs Alastair D'Silva
2020-03-04 15:21   ` Frederic Barrat
2020-03-12  4:24     ` Alastair D'Silva
2020-03-05  3:11   ` Andrew Donnellan
2020-03-12  4:58     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 24/27] powerpc/powernv/pmem: Expose SMART data via ndctl Alastair D'Silva
2020-03-04 15:40   ` Frederic Barrat
2020-03-05  3:36   ` Andrew Donnellan
2020-03-12 23:14     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 25/27] powerpc/powernv/pmem: Expose the serial number in sysfs Alastair D'Silva
2020-02-28  6:25   ` Andrew Donnellan
2020-02-28  7:15     ` Greg Kroah-Hartman
2020-03-01 23:42       ` Alastair D'Silva
2020-03-02  5:38         ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 26/27] powerpc/powernv/pmem: Expose the firmware version " Alastair D'Silva
2020-03-02  7:35   ` Andrew Donnellan
2020-03-04  4:11     ` Alastair D'Silva
2020-02-21  3:27 ` [PATCH v3 27/27] MAINTAINERS: Add myself & nvdimm/ocxl to ocxl Alastair D'Silva
2020-02-21  5:35   ` Andrew Donnellan
2020-02-21 16:21 ` [PATCH v3 00/27] Add support for OpenCAPI Persistent Memory devices Dan Williams
2020-02-21 16:24   ` Dan Williams
2020-02-24  4:34   ` Alastair D'Silva
2020-02-24  4:37     ` Matthew Wilcox
2020-02-24  4:42       ` Alastair D'Silva
2020-02-24  6:51         ` Oliver O'Halloran
2020-02-26  0:13           ` Alastair D'Silva
2020-02-26  0:32             ` Dan Williams
2020-02-26  0:35               ` Alastair D'Silva

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