[Xen-changelog] This patch addresses Rustys' [1]suggestions. Most visibly:

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID a5994e258f777703b46a8433238bd72c8bf8c1cb
# Parent  2f75dac09365959d87709d15a181201abf189cb8
This patch addresses Rustys' [1]suggestions.  Most visibly:

Entries in the store:
/cpus/cpuX/online -> /cpu/X/availability

Values:
0|1 -> online|offline

Signed-off-by: Ryan Harper <ryanh@xxxxxxxxxx>

diff -r 2f75dac09365 -r a5994e258f77 
linux-2.6-xen-sparse/arch/xen/i386/kernel/smpboot.c
--- a/linux-2.6-xen-sparse/arch/xen/i386/kernel/smpboot.c       Thu Aug 11 
18:03:22 2005
+++ b/linux-2.6-xen-sparse/arch/xen/i386/kernel/smpboot.c       Thu Aug 11 
20:57:09 2005
@@ -1353,83 +1353,82 @@
                printk(KERN_ALERT "Error creating hotplug_cpu process!\n");
 }
 
-static void handle_cpus_watch(struct xenbus_watch *, const char *);
-static struct notifier_block xsn_cpus;
+static void handle_vcpu_hotplug_event(struct xenbus_watch *, const char *);
+static struct notifier_block xsn_cpu;
 
 /* xenbus watch struct */
-static struct xenbus_watch cpus_watch = {
-       .node = "cpus",
-       .callback = handle_cpus_watch,
+static struct xenbus_watch cpu_watch = {
+       .node = "cpu",
+       .callback = handle_vcpu_hotplug_event
 };
 
-static int setup_cpus_watcher(struct notifier_block *notifier,
+/* NB: Assumes xenbus_lock is held! */
+static int setup_cpu_watcher(struct notifier_block *notifier,
                              unsigned long event, void *data)
 {
        int err = 0;
 
-       down(&xenbus_lock);
-       err = register_xenbus_watch(&cpus_watch);
-       up(&xenbus_lock);
+       BUG_ON(down_trylock(&xenbus_lock) == 0);
+       err = register_xenbus_watch(&cpu_watch);
 
        if (err) {
-               printk("Failed to set cpus watcher\n");
-       }
+               printk("Failed to register watch on /cpu\n");
+       }
+
        return NOTIFY_DONE;
 }
 
-static void handle_cpus_watch(struct xenbus_watch *watch, const char *node)
+static void handle_vcpu_hotplug_event(struct xenbus_watch *watch, const char 
*node)
 {
        static DECLARE_WORK(vcpu_hotplug_work, __vcpu_hotplug_handler, NULL);
        struct vcpu_hotplug_handler_t *handler = &vcpu_hotplug_handler;
        ssize_t ret;
-       int err, cpu, state;
+       int err, cpu;
+       char state[8];
        char dir[32];
        char *cpustr;
 
-       /* get a pointer to start of cpus/cpu string */
-       if ((cpustr = strstr(node, "cpus/cpu")) != NULL) {
+       /* get a pointer to start of cpu string */
+       if ((cpustr = strstr(node, "cpu/")) != NULL) {
 
                /* find which cpu state changed, note vcpu for handler */
-               sscanf(cpustr, "cpus/cpu%d", &cpu);
+               sscanf(cpustr, "cpu/%d", &cpu);
                handler->vcpu = cpu;
 
                /* calc the dir for xenbus read */
-               sprintf(dir, "cpus/cpu%d", cpu);
-
-               /* make sure watch that was triggered is changes to the online 
key */
-               if ((strcmp(node + strlen(dir), "/online")) != 0)
+               sprintf(dir, "cpu/%d", cpu);
+
+               /* make sure watch that was triggered is changes to the correct 
key */
+               if ((strcmp(node + strlen(dir), "/availability")) != 0)
                        return;
 
                /* get the state value */
-               xenbus_transaction_start("cpus");
-               err = xenbus_scanf(dir, "online", "%d", &state);
+               xenbus_transaction_start("cpu");
+               err = xenbus_scanf(dir, "availability", "%s", state);
                xenbus_transaction_end(0);
 
                if (err != 1) {
                        printk(KERN_ERR
-                              "XENBUS: Unable to read cpu online state\n");
+                              "XENBUS: Unable to read cpu state\n");
                        return;
                }
 
                /* if we detect a state change, take action */
-               switch (state) {
+               if (strcmp(state, "online") == 0) {
                        /* offline -> online */
-               case 1:
                        if (!cpu_isset(cpu, cpu_online_map)) {
                                handler->fn = (void *)&cpu_up;
                                ret = schedule_work(&vcpu_hotplug_work);
-                       }
-                       break;
+                       } 
+               } else if (strcmp(state, "offline") == 0) {
                        /* online -> offline */
-               case 0:
                        if (cpu_isset(cpu, cpu_online_map)) {
                                handler->fn = (void *)&cpu_down;
                                ret = schedule_work(&vcpu_hotplug_work);
-                       }
-                       break;
-               default:
+                       } 
+               } else {
                        printk(KERN_ERR
-                              "XENBUS: unknown state(%d) on node(%s)\n", state,
+                              "XENBUS: unknown state(%s) on node(%s)\n", state,
                               node);
                }
        }
@@ -1438,13 +1437,9 @@
 
 static int __init setup_vcpu_hotplug_event(void)
 {
-       xsn_cpus.notifier_call = setup_cpus_watcher;
-
-       if (xen_start_info.store_evtchn) {
-               setup_cpus_watcher(&xsn_cpus, 0, NULL);
-       } else {
-               register_xenstore_notifier(&xsn_cpus);
-       }
+       xsn_cpu.notifier_call = setup_cpu_watcher;
+
+       register_xenstore_notifier(&xsn_cpu);
 
        return 0;
 }
diff -r 2f75dac09365 -r a5994e258f77 tools/python/xen/xend/XendDomainInfo.py
--- a/tools/python/xen/xend/XendDomainInfo.py   Thu Aug 11 18:03:22 2005
+++ b/tools/python/xen/xend/XendDomainInfo.py   Thu Aug 11 20:57:09 2005
@@ -557,12 +557,12 @@
 
     def exportVCPUSToDB(self, vcpus):
         for v in range(0,vcpus):
-            path = "/cpus/cpu%d"%(v)
+            path = "/cpu/%d"%(v)
             if not self.vcpusdb.has_key(path):
                 self.vcpusdb[path] = self.db.addChild(path)
             db = self.vcpusdb[path]
-            log.debug("writing key online=1 to path %s in store"%(path))
-            db['online'] = "1"
+            log.debug("writing key availability=online to path %s in 
store"%(path))
+            db['availability'] = "online"
             db.saveDB(save=True)
 
     def init_image(self):
@@ -951,16 +951,16 @@
         """
         db = ""
         try:
-            db = self.vcpusdb['/cpus/cpu%d'%(vcpu)]
+            db = self.vcpusdb['/cpu/%d'%(vcpu)]
         except:
             log.error("Invalid VCPU")
             return
 
         if self.store_channel:
             if int(state) == 0:
-                db['online'] = "0"
+                db['availability'] = "offline"
             else:
-                db['online'] = "1"
+                db['availability'] = "online"
 
         db.saveDB(save=True)
 

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