Re: [Xen-devel] [PATCH 10/10] Xen: update pcpu online/offline logic

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

On Fri, Dec 23, 2011 at 10:32:12AM +0000, Liu, Jinsong wrote:
> >From 1e59d2ec2ff93b42c86d18c7cc9432ca2172a795 Mon Sep 17 00:00:00 2001
> From: Liu Jinsong <jinsong.liu@xxxxxxxxx>
> Date: Wed, 14 Dec 2011 21:06:11 +0800
> Subject: [PATCH 10/10] Xen: update pcpu online/offline logic
> 
> This patch update pcpu online/offline logic.

Roll them in the patch you posted please.
> 
> It closes cpu0's /sys/.../xen_pcpu0/online authority to user.
> It also simplifies pcpu sync by removing redundant logic.
> 
> Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> Signed-off-by: Jiang, Yunhong <yunhong.jiang@xxxxxxxxx>
> ---
>  drivers/xen/pcpu.c |   71 
> ++++++++++++++--------------------------------------
>  1 files changed, 19 insertions(+), 52 deletions(-)
> 
> diff --git a/drivers/xen/pcpu.c b/drivers/xen/pcpu.c
> index 6d1a770..1d32784 100644
> --- a/drivers/xen/pcpu.c
> +++ b/drivers/xen/pcpu.c
> @@ -24,7 +24,6 @@ static RAW_NOTIFIER_HEAD(xen_pcpu_chain);
>  
>  struct xen_pcpus {
>       struct list_head list;
> -     int present;
>  };
>  static struct xen_pcpus xen_pcpus;
>  
> @@ -189,9 +188,13 @@ static int pcpu_sysdev_init(struct pcpu *cpu)
>               kfree(cpu);
>               return -1;
>       }
> -     sysdev_create_file(&cpu->sysdev, &attr_online);
>       sysdev_create_file(&cpu->sysdev, &attr_apic_id);
>       sysdev_create_file(&cpu->sysdev, &attr_acpi_id);
> +
> +     /* Not open cpu0 online access to user */
> +     if (cpu->sysdev.id)
> +             sysdev_create_file(&cpu->sysdev, &attr_online);
> +
>       return 0;
>  }
>  
> @@ -239,17 +242,10 @@ static struct pcpu *init_pcpu(struct xenpf_pcpuinfo 
> *info)
>       return pcpu;
>  }
>  
> -#define PCPU_NO_CHANGE                       0
> -#define PCPU_ADDED                   1
> -#define PCPU_ONLINE_OFFLINE          2
> -#define PCPU_REMOVED                 3
>  /*
>   * Caller should hold the pcpu lock
> - * < 0: Something wrong
> - * 0: No changes
> - * > 0: State changed
>   */
> -static struct pcpu *_sync_pcpu(int cpu_num, int *max_id, int *result)
> +static int _sync_pcpu(int cpu_num, int *max_id)
>  {
>       struct pcpu *pcpu = NULL;
>       struct xenpf_pcpuinfo *info;
> @@ -259,14 +255,12 @@ static struct pcpu *_sync_pcpu(int cpu_num, int 
> *max_id, int *result)
>       };
>       int ret;
>  
> -     *result = -1;
> -
>       info = &op.u.pcpu_info;
>       info->xen_cpuid = cpu_num;
>  
>       ret = HYPERVISOR_dom0_op(&op);
>       if (ret)
> -             return NULL;
> +             return -1;
>  
>       if (max_id)
>               *max_id = op.u.pcpu_info.max_present;
> @@ -275,28 +269,24 @@ static struct pcpu *_sync_pcpu(int cpu_num, int 
> *max_id, int *result)
>  
>       if (info->flags & XEN_PCPU_FLAGS_INVALID) {
>               /* The pcpu has been removed */
> -             *result = PCPU_NO_CHANGE;
>               if (pcpu) {
>                       raw_notifier_call_chain(&xen_pcpu_chain,
>                         XEN_PCPU_REMOVE,
>                         (void *)(long)pcpu->xen_id);
>                       xen_pcpu_free(pcpu);
> -                     *result = PCPU_REMOVED;
>               }
> -             return NULL;
> +             return 0;
>       }
>  
>  
>       if (!pcpu) {
> -             *result = PCPU_ADDED;
>               pcpu = init_pcpu(info);
>               if (pcpu == NULL) {
>                       printk(KERN_WARNING "Failed to init pcpu %x\n",
>                         info->xen_cpuid);
> -                       *result = -1;
> +                     return -1;
>               }
>       } else {
> -             *result = PCPU_NO_CHANGE;
>               /*
>                * Old PCPU is replaced with a new pcpu, this means
>                * several virq is missed, will it happen?
> @@ -307,10 +297,10 @@ static struct pcpu *_sync_pcpu(int cpu_num, int 
> *max_id, int *result)
>                       pcpu->apic_id = info->apic_id;
>                       pcpu->acpi_id = info->acpi_id;
>               }
> -             if (xen_pcpu_online_check(info, pcpu))
> -                     *result = PCPU_ONLINE_OFFLINE;
> +             xen_pcpu_online_check(info, pcpu);
>       }
> -     return pcpu;
> +
> +     return 0;
>  }
>  
>  int xen_pcpu_index(uint32_t id, int is_acpiid)
> @@ -353,50 +343,27 @@ static int xen_sync_pcpus(void)
>       /*
>        * Boot cpu always have cpu_id 0 in xen
>        */
> -     int cpu_num = 0, max_id = 0, result = 0, present = 0;
> +     int cpu_num = 0, max_id = 0, ret = 0;
>       struct list_head *elem, *tmp;
>       struct pcpu *pcpu;
>  
>       get_pcpu_lock();
>  
> -     while ((result >= 0) && (cpu_num <= max_id)) {
> -             pcpu = _sync_pcpu(cpu_num, &max_id, &result);
> -
> -             printk(KERN_DEBUG "sync cpu %x get result %x max_id %x\n",
> -                     cpu_num, result, max_id);
> -
> -             switch (result) {
> -             case PCPU_NO_CHANGE:
> -                     if (pcpu)
> -                             present++;
> -                     break;
> -             case PCPU_ADDED:
> -             case PCPU_ONLINE_OFFLINE:
> -                     present++;
> -             case PCPU_REMOVED:
> -                     break;
> -             default:
> -                     printk(KERN_WARNING "Failed to sync pcpu %x\n",
> -                       cpu_num);
> -                     break;
> -
> -             }
> +     while (!ret && (cpu_num <= max_id)) {
> +             ret = _sync_pcpu(cpu_num, &max_id);
>               cpu_num++;
>       }
>  
> -     if (result < 0) {
> +     if (ret < 0) {
>               list_for_each_safe(elem, tmp, &xen_pcpus.list) {
>                       pcpu = list_entry(elem, struct pcpu, pcpu_list);
>                       xen_pcpu_free(pcpu);
>               }
> -             present = 0;
>       }
>  
> -     xen_pcpus.present = present;
> -
>       put_pcpu_lock();
>  
> -     return 0;
> +     return ret;
>  }
>  
>  static void xen_pcpu_dpc(struct work_struct *work)
> @@ -436,10 +403,10 @@ static int __init xen_pcpu_init(void)
>       }
>  
>       INIT_LIST_HEAD(&xen_pcpus.list);
> -     xen_pcpus.present = 0;
>  
>       xen_sync_pcpus();
> -     if (xen_pcpus.present > 0)
> +
> +     if (!list_empty(&xen_pcpus.list))
>               err = bind_virq_to_irqhandler(VIRQ_PCPU_STATE,
>                       0, xen_pcpu_interrupt, 0, "pcpu", NULL);
>       if (err < 0)
> -- 
> 1.6.5.6


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