Re: [PATCH 3/3] Xen physical cpus interface (V2)

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, May 10, 2012 at 03:06:14PM +0000, Liu, Jinsong wrote:
> >From 7aa4cf7c1172e24611dc76163397b8708acacc59 Mon Sep 17 00:00:00 2001
> From: Liu, Jinsong <jinsong.liu@intel.com>
> Date: Fri, 11 May 2012 06:55:35 +0800
> Subject: [PATCH 3/3] Xen physical cpus interface
> 
> Manage physical cpus in dom0, get physical cpus info and provide sys interface.
> 
> Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
> Signed-off-by: Jiang, Yunhong <yunhong.jiang@intel.com>
> ---
>  .../ABI/testing/sysfs-devices-system-xen_cpu       |   20 +
>  drivers/xen/Makefile                               |    1 +
>  drivers/xen/pcpu.c                                 |  374 ++++++++++++++++++++
>  include/xen/interface/platform.h                   |    8 +
>  include/xen/interface/xen.h                        |    1 +
>  5 files changed, 404 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-devices-system-xen_cpu
>  create mode 100644 drivers/xen/pcpu.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-devices-system-xen_cpu b/Documentation/ABI/testing/sysfs-devices-system-xen_cpu
> new file mode 100644
> index 0000000..9ca02fb
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-devices-system-xen_cpu
> @@ -0,0 +1,20 @@
> +What:		/sys/devices/system/xen_cpu/
> +Date:		May 2012
> +Contact:	Liu, Jinsong <jinsong.liu@intel.com>
> +Description:
> +		A collection of global/individual Xen physical cpu attributes
> +
> +		Individual physical cpu attributes are contained in
> +		subdirectories named by the Xen's logical cpu number, e.g.:
> +		/sys/devices/system/xen_cpu/xen_cpu#/
> +
> +
> +What:		/sys/devices/system/xen_cpu/xen_cpu#/online
> +Date:		May 2012
> +Contact:	Liu, Jinsong <jinsong.liu@intel.com>
> +Description:
> +		Interface to online/offline Xen physical cpus
> +
> +		When running under Xen platform, it provide user interface
> +		to online/offline physical cpus, except cpu0 due to several
> +		logic restrictions and assumptions.
> diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
> index 1d3e763..d12d14d 100644
> --- a/drivers/xen/Makefile
> +++ b/drivers/xen/Makefile
> @@ -19,6 +19,7 @@ obj-$(CONFIG_XEN_PVHVM)			+= platform-pci.o
>  obj-$(CONFIG_XEN_TMEM)			+= tmem.o
>  obj-$(CONFIG_SWIOTLB_XEN)		+= swiotlb-xen.o
>  obj-$(CONFIG_XEN_DOM0)			+= pci.o
> +obj-$(CONFIG_XEN_DOM0)			+= pcpu.o
>  obj-$(CONFIG_XEN_PCIDEV_BACKEND)	+= xen-pciback/
>  obj-$(CONFIG_XEN_PRIVCMD)		+= xen-privcmd.o
>  obj-$(CONFIG_XEN_ACPI_PROCESSOR)	+= xen-acpi-processor.o
> diff --git a/drivers/xen/pcpu.c b/drivers/xen/pcpu.c
> new file mode 100644
> index 0000000..9014ff1
> --- /dev/null
> +++ b/drivers/xen/pcpu.c
> @@ -0,0 +1,374 @@
> +/******************************************************************************
> + * pcpu.c
> + * Management physical cpu in dom0, get pcpu info and provide sys interface
> + *
> + * Copyright (c) 2012 Intel Corporation
> + * Author: Liu, Jinsong <jinsong.liu@intel.com>
> + * Author: Jiang, Yunhong <yunhong.jiang@intel.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation; or, when distributed
> + * separately from the Linux kernel or incorporated into other
> + * software packages, subject to the following license:
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this source file (the "Software"), to deal in the Software without
> + * restriction, including without limitation the rights to use, copy, modify,
> + * merge, publish, distribute, sublicense, and/or sell copies of the Software,
> + * and to permit persons to whom the Software is furnished to do so, subject to
> + * the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#include <linux/interrupt.h>
> +#include <linux/spinlock.h>
> +#include <linux/cpu.h>
> +#include <linux/stat.h>
> +#include <linux/capability.h>
> +
> +#include <xen/xen.h>
> +#include <xen/xenbus.h>
> +#include <xen/events.h>
> +#include <xen/interface/platform.h>
> +#include <asm/xen/hypervisor.h>
> +#include <asm/xen/hypercall.h>
> +
> +#define XEN_PCPU "xen_cpu: "
> +
> +/*
> + * @cpu_id: Xen physical cpu logic number
> + * @flags: Xen physical cpu status flag
> + * - XEN_PCPU_FLAGS_ONLINE: cpu is online
> + * - XEN_PCPU_FLAGS_INVALID: cpu is not present
> + */
> +struct pcpu {
> +	struct list_head list;
> +	struct device dev;
> +	uint32_t cpu_id;
> +	uint32_t flags;
> +};
> +
> +static struct bus_type xen_pcpu_subsys = {
> +	.name = "xen_cpu",
> +	.dev_name = "xen_cpu",
> +};
> +
> +static DEFINE_MUTEX(xen_pcpu_lock);
> +
> +static LIST_HEAD(xen_pcpus);

So what about the recommendation to get rid of that and
instead do

struct pcpu *xen_cpu;

and use that as a list? Meaning
.. snip..
> +{
> +	struct list_head *cur;
> +	struct pcpu *pcpu;
> +
> +	list_for_each(cur, &xen_pcpus) {
> +		pcpu = list_entry(cur, struct pcpu, list);
> +		if (pcpu->cpu_id == cpu_id)
> +			return pcpu;
> +	}

do:
struct pcpu *pcpu;

list_for_each_entry(pcpu, xen_pcpus, list)
	if (pcpu->cpu_id == cpu_id)
		return pcpu;
?

and such.