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Message-ID: <DE8DF0795D48FD4CA783C40EC82923359771@SHSMSX101.ccr.corp.intel.com>
Date:	Fri, 23 Dec 2011 10:32:12 +0000
From:	"Liu, Jinsong" <jinsong.liu@...el.com>
To:	"konrad.wilk@...cle.com" <konrad.wilk@...cle.com>
CC:	"Jiang, Yunhong" <yunhong.jiang@...el.com>,
	"jeremy.fitzhardinge@...rix.com" <jeremy.fitzhardinge@...rix.com>,
	"Shan, Haitao" <haitao.shan@...el.com>,
	"Zhao, Yakui" <yakui.zhao@...el.com>,
	"Brown, Len" <len.brown@...el.com>,
	"Luck, Tony" <tony.luck@...el.com>,
	"Kleen, Andi" <andi.kleen@...el.com>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	Kernel development list <linux-kernel@...r.kernel.org>
Subject: [PATCH 10/10] Xen: update pcpu online/offline logic

>From 1e59d2ec2ff93b42c86d18c7cc9432ca2172a795 Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@...el.com>
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.

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@...el.com>
Signed-off-by: Jiang, Yunhong <yunhong.jiang@...el.com>
---
 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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