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From: Dan Williams <dan.j.williams@intel.com>
To: <shiju.jose@huawei.com>, <linux-cxl@vger.kernel.org>,
	<linux-acpi@vger.kernel.org>, <linux-mm@kvack.org>,
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	<kangkang.shen@futurewei.com>, <wanghuiqiang@huawei.com>,
	<linuxarm@huawei.com>, <shiju.jose@huawei.com>
Subject: RE: [RFC PATCH v8 01/10] ras: scrub: Add scrub subsystem
Date: Thu, 9 May 2024 14:47:56 -0700	[thread overview]
Message-ID: <663d448c2ef3_1c0a1929453@dwillia2-xfh.jf.intel.com.notmuch> (raw)
In-Reply-To: <20240419164720.1765-2-shiju.jose@huawei.com>

shiju.jose@ wrote:
> From: Shiju Jose <shiju.jose@huawei.com>
> 
> Add scrub subsystem supports configuring the memory scrubbers
> in the system. The scrub subsystem provides the interface for
> registering the scrub devices. The scrub control attributes
> are provided to the user in /sys/class/ras/rasX/scrub
> 
> Co-developed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
> ---
>  .../ABI/testing/sysfs-class-scrub-configure   |  47 +++
>  drivers/ras/Kconfig                           |   7 +
>  drivers/ras/Makefile                          |   1 +
>  drivers/ras/memory_scrub.c                    | 271 ++++++++++++++++++
>  include/linux/memory_scrub.h                  |  37 +++
>  5 files changed, 363 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-scrub-configure
>  create mode 100755 drivers/ras/memory_scrub.c
>  create mode 100755 include/linux/memory_scrub.h
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-scrub-configure b/Documentation/ABI/testing/sysfs-class-scrub-configure
> new file mode 100644
> index 000000000000..3ed77dbb00ad
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-scrub-configure
> @@ -0,0 +1,47 @@
> +What:		/sys/class/ras/
> +Date:		March 2024
> +KernelVersion:	6.9
> +Contact:	linux-kernel@vger.kernel.org
> +Description:
> +		The ras/ class subdirectory belongs to the
> +		common ras features such as scrub subsystem.

Why create "ras" class versus just a "srcub" class? I am otherwise not
aware of a precedent for class device hierarchy. For example, on my
system there is:

/sys/class/
├── scsi_device
├── scsi_disk
├── scsi_generic
└── scsi_host

...not:

/sys/class/scsi/
├── device
├── disk
├── generic
└── host


> +
> +What:		/sys/class/ras/rasX/scrub/
> +Date:		March 2024
> +KernelVersion:	6.9
> +Contact:	linux-kernel@vger.kernel.org
> +Description:
> +		The /sys/class/ras/ras{0,1,2,3,...}/scrub directories
> +		correspond to each scrub device registered with the
> +		scrub subsystem.

I notice there are some visibility rules in the code, but those
expectations are not documented here.

This documentation would also help developers writing new users of
scrub_device_register().

> +
> +What:		/sys/class/ras/rasX/scrub/name
> +Date:		March 2024
> +KernelVersion:	6.9
> +Contact:	linux-kernel@vger.kernel.org
> +Description:
> +		(RO) name of the memory scrubber
> +
> +What:		/sys/class/ras/rasX/scrub/enable_background
> +Date:		March 2024
> +KernelVersion:	6.9
> +Contact:	linux-kernel@vger.kernel.org
> +Description:
> +		(RW) Enable/Disable background(patrol) scrubbing if supported.
> +
> +What:		/sys/class/ras/rasX/scrub/rate_available
> +Date:		March 2024
> +KernelVersion:	6.9
> +Contact:	linux-kernel@vger.kernel.org
> +Description:
> +		(RO) Supported range for the scrub rate by the scrubber.
> +		The scrub rate represents in hours.
> +
> +What:		/sys/class/ras/rasX/scrub/rate
> +Date:		March 2024
> +KernelVersion:	6.9
> +Contact:	linux-kernel@vger.kernel.org
> +Description:
> +		(RW) The scrub rate specified and it must be with in the
> +		supported range by the scrubber.
> +		The scrub rate represents in hours.
> diff --git a/drivers/ras/Kconfig b/drivers/ras/Kconfig
> index fc4f4bb94a4c..181701479564 100644
> --- a/drivers/ras/Kconfig
> +++ b/drivers/ras/Kconfig
> @@ -46,4 +46,11 @@ config RAS_FMPM
>  	  Memory will be retired during boot time and run time depending on
>  	  platform-specific policies.
>  
> +config SCRUB
> +	tristate "Memory scrub driver"
> +	help
> +	  This option selects the memory scrub subsystem, supports
> +	  configuring the parameters of underlying scrubbers in the
> +	  system for the DRAM memories.
> +
>  endif
> diff --git a/drivers/ras/Makefile b/drivers/ras/Makefile
> index 11f95d59d397..89bcf0d84355 100644
> --- a/drivers/ras/Makefile
> +++ b/drivers/ras/Makefile
> @@ -2,6 +2,7 @@
>  obj-$(CONFIG_RAS)	+= ras.o
>  obj-$(CONFIG_DEBUG_FS)	+= debugfs.o
>  obj-$(CONFIG_RAS_CEC)	+= cec.o
> +obj-$(CONFIG_SCRUB)	+= memory_scrub.o
>  
>  obj-$(CONFIG_RAS_FMPM)	+= amd/fmpm.o
>  obj-y			+= amd/atl/
> diff --git a/drivers/ras/memory_scrub.c b/drivers/ras/memory_scrub.c
> new file mode 100755
> index 000000000000..7e995380ec3a
> --- /dev/null
> +++ b/drivers/ras/memory_scrub.c
> @@ -0,0 +1,271 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Memory scrub subsystem supports configuring the registered
> + * memory scrubbers.
> + *
> + * Copyright (c) 2024 HiSilicon Limited.
> + */
> +
> +#define pr_fmt(fmt)     "MEM SCRUB: " fmt
> +
> +#include <linux/acpi.h>
> +#include <linux/bitops.h>
> +#include <linux/delay.h>
> +#include <linux/kfifo.h>
> +#include <linux/memory_scrub.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +
> +/* memory scrubber config definitions */
> +#define SCRUB_ID_PREFIX "ras"
> +#define SCRUB_ID_FORMAT SCRUB_ID_PREFIX "%d"
> +
> +static DEFINE_IDA(scrub_ida);
> +
> +struct scrub_device {
> +	int id;
> +	struct device dev;
> +	const struct scrub_ops *ops;
> +};
> +
> +#define to_scrub_device(d) container_of(d, struct scrub_device, dev)
> +static ssize_t enable_background_store(struct device *dev,
> +				       struct device_attribute *attr,
> +				       const char *buf, size_t len)
> +{
> +	struct scrub_device *scrub_dev = to_scrub_device(dev);
> +	bool enable;
> +	int ret;
> +
> +	ret = kstrtobool(buf, &enable);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = scrub_dev->ops->set_enabled_bg(dev, enable);
> +	if (ret)
> +		return ret;

It strikes me as somewhat pointless to have such a thin sysfs
implementation whose only job is to call down into a callback to do the
work. Unless there are other consumers of 'struct scrub_ops' outside of
these sysfs files why not just have the low-level drivers register their
corresponding attributes themselves?

Unless the functionality is truly generic just let the low-level driver
be responsible for conforming to the sysfs ABI expectations, and, for
example, each register their own "enable_background" attribute if they
support that semantic.

So scrub_device_register() would grow a 'const struct attribute_group
**groups' argument, or something along those lines.


  parent reply	other threads:[~2024-05-09 21:48 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-19 16:47 [RFC PATCH v8 00/10] ras: scrub: introduce subsystem + CXL/ACPI-RAS2 drivers shiju.jose
2024-04-19 16:47 ` [RFC PATCH v8 01/10] ras: scrub: Add scrub subsystem shiju.jose
2024-04-24 20:25   ` fan
2024-04-25 10:38     ` Shiju Jose
2024-04-25 10:15   ` Borislav Petkov
2024-04-25 18:11     ` Shiju Jose
2024-05-06 10:30       ` Borislav Petkov
2024-05-08 16:59         ` Shiju Jose
2024-05-08 17:20           ` Borislav Petkov
2024-05-08 17:44             ` Shiju Jose
2024-05-08 19:25               ` Borislav Petkov
2024-05-09  9:19                 ` Jonathan Cameron
2024-05-09 15:52                   ` Borislav Petkov
2024-05-09 20:03                     ` Borislav Petkov
2024-05-09 21:21                       ` Dan Williams
2024-05-09 21:51                         ` Borislav Petkov
2024-05-09 22:59                           ` Dan Williams
2024-05-10  9:25                             ` Borislav Petkov
2024-05-10 17:13                               ` Dan Williams
2024-05-11 10:17                                 ` Borislav Petkov
2024-05-17 11:15                                   ` Jonathan Cameron
2024-05-17 11:44                                     ` Jonathan Cameron
2024-05-21  8:06                                       ` Borislav Petkov
2024-05-22  9:40                                         ` Jonathan Cameron
2024-05-27  9:09                                           ` Borislav Petkov
2024-05-20 10:54                                   ` Shiju Jose
2024-05-20 11:58                                     ` Jonathan Cameron
2024-05-27  9:21                                       ` Borislav Petkov
2024-05-28  9:06                                         ` Jonathan Cameron
2024-06-06 16:05                                           ` Borislav Petkov
2024-05-10 13:31                     ` Jonathan Cameron
2024-05-09 21:47   ` Dan Williams [this message]
2024-05-10  9:03     ` Jonathan Cameron
2024-04-19 16:47 ` [RFC PATCH v8 02/10] cxl/mbox: Add GET_SUPPORTED_FEATURES mailbox command shiju.jose
2024-04-19 16:47 ` [RFC PATCH v8 03/10] cxl/mbox: Add GET_FEATURE " shiju.jose
2024-04-24 23:19   ` fan
2024-04-25 10:38     ` Shiju Jose
2024-04-19 16:47 ` [RFC PATCH v8 04/10] cxl/mbox: Add SET_FEATURE " shiju.jose
2024-04-25 17:26   ` fan
2024-04-19 16:47 ` [RFC PATCH v8 05/10] cxl/memscrub: Add CXL device patrol scrub control feature shiju.jose
2024-04-26 23:56   ` fan
2024-04-29 11:20     ` Shiju Jose
2024-04-29 12:21       ` Jonathan Cameron
2024-05-10  0:26   ` Dan Williams
2024-05-10 11:23     ` Jonathan Cameron
2024-04-19 16:47 ` [RFC PATCH v8 06/10] ACPICA: Add __free() based cleanup function for acpi_put_table shiju.jose
2024-04-19 18:06   ` Jonathan Cameron
2024-04-19 16:47 ` [RFC PATCH v8 07/10] platform: Add __free() based cleanup function for platform_device_put shiju.jose
2024-04-19 16:47 ` [RFC PATCH v8 08/10] ACPI:RAS2: Add ACPI RAS2 driver shiju.jose
2024-06-05 21:32   ` Daniel Ferguson
2024-04-19 16:47 ` [RFC PATCH v8 09/10] ras: scrub: Add scrub control attributes for ACPI RAS2 shiju.jose
2024-04-19 16:47 ` [RFC PATCH v8 10/10] ras: scrub: ACPI RAS2: Add memory ACPI RAS2 driver shiju.jose
2024-06-05 21:33   ` Daniel Ferguson
2024-06-07 15:46     ` Shiju Jose

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