[Xen-changelog] Fix vcpu-hotplug xenbus watch handler and setup.

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

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID def91f2dbc890da85a6e159d71a30ff6157a7a9f
# Parent  43b40ae7904c6d0121e9a2e547b8d814945ca2ac
Fix vcpu-hotplug xenbus watch handler and setup.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>

diff -r 43b40ae7904c -r def91f2dbc89 
linux-2.6-xen-sparse/arch/xen/i386/kernel/smpboot.c
--- a/linux-2.6-xen-sparse/arch/xen/i386/kernel/smpboot.c       Wed Oct 12 
10:13:00 2005
+++ b/linux-2.6-xen-sparse/arch/xen/i386/kernel/smpboot.c       Wed Oct 12 
10:47:16 2005
@@ -64,6 +64,7 @@
 
 #include <asm-xen/evtchn.h>
 #include <asm-xen/xen-public/vcpu.h>
+#include <asm-xen/xenbus.h>
 
 /* Set if we find a B stepping CPU */
 static int __initdata smp_b_stepping;
@@ -1289,117 +1290,51 @@
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-#include <asm-xen/xenbus.h>
-/* hotplug down/up funtion pointer and target vcpu */
-struct vcpu_hotplug_handler_t {
-       void (*fn) (int vcpu);
-       u32 vcpu;
-};
-static struct vcpu_hotplug_handler_t vcpu_hotplug_handler;
-
-static int vcpu_hotplug_cpu_process(void *unused)
-{
-       struct vcpu_hotplug_handler_t *handler = &vcpu_hotplug_handler;
-
-       if (handler->fn) {
-               (*(handler->fn)) (handler->vcpu);
-               handler->fn = NULL;
-       }
-       return 0;
-}
-
-static void __vcpu_hotplug_handler(void *unused)
-{
-       int err;
-
-       err = kernel_thread(vcpu_hotplug_cpu_process,
-                           NULL, CLONE_FS | CLONE_FILES);
-       if (err < 0)
-               printk(KERN_ALERT "Error creating hotplug_cpu process!\n");
-}
-
-static void handle_vcpu_hotplug_event(struct xenbus_watch *, const char *);
-static struct notifier_block xsn_cpu;
-
-/* xenbus watch struct */
-static struct xenbus_watch cpu_watch = {
-       .node = "cpu",
-       .callback = handle_vcpu_hotplug_event
-};
+
+static void handle_vcpu_hotplug_event(
+       struct xenbus_watch *watch, const char **vec, unsigned int len)
+{
+       int err, cpu;
+       char dir[32], state[32];
+       char *cpustr;
+       const char *node = vec[XS_WATCH_PATH];
+
+       if ((cpustr = strstr(node, "cpu/")) == NULL)
+               return;
+
+       sscanf(cpustr, "cpu/%d", &cpu);
+
+       sprintf(dir, "cpu/%d", cpu);
+       err = xenbus_scanf(NULL, dir, "availability", "%s", state);
+       if (err != 1) {
+               printk(KERN_ERR "XENBUS: Unable to read cpu state\n");
+               return;
+       }
+
+       if (strcmp(state, "online") == 0)
+               (void)cpu_up(cpu);
+       else if (strcmp(state, "offline") == 0)
+               (void)cpu_down(cpu);
+       else
+               printk(KERN_ERR "XENBUS: unknown state(%s) on node(%s)\n",
+                      state, node);
+}
 
 static int setup_cpu_watcher(struct notifier_block *notifier,
                              unsigned long event, void *data)
 {
-       int err;
-
-       err = register_xenbus_watch(&cpu_watch);
-       if (err)
-               printk("Failed to register watch on /cpu\n");
-
+       static struct xenbus_watch cpu_watch = {
+               .node = "cpu",
+               .callback = handle_vcpu_hotplug_event };
+       (void)register_xenbus_watch(&cpu_watch);
        return NOTIFY_DONE;
 }
 
-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;
-       char state[8];
-       char dir[32];
-       char *cpustr;
-
-       /* 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, "cpu/%d", &cpu);
-               handler->vcpu = cpu;
-
-               /* calc the dir for xenbus read */
-               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 */
-               err = xenbus_scanf(NULL, dir, "availability", "%s", state);
-
-               if (err != 1) {
-                       printk(KERN_ERR
-                              "XENBUS: Unable to read cpu state\n");
-                       return;
-               }
-
-               /* if we detect a state change, take action */
-               if (strcmp(state, "online") == 0) {
-                       /* offline -> online */
-                       if (!cpu_isset(cpu, cpu_online_map)) {
-                               handler->fn = (void *)&cpu_up;
-                               ret = schedule_work(&vcpu_hotplug_work);
-                       } 
-               } else if (strcmp(state, "offline") == 0) {
-                       /* online -> offline */
-                       if (cpu_isset(cpu, cpu_online_map)) {
-                               handler->fn = (void *)&cpu_down;
-                               ret = schedule_work(&vcpu_hotplug_work);
-                       } 
-               } else {
-                       printk(KERN_ERR
-                              "XENBUS: unknown state(%s) on node(%s)\n", state,
-                              node);
-               }
-       }
-       return;
-}
-
 static int __init setup_vcpu_hotplug_event(void)
 {
-       xsn_cpu.notifier_call = setup_cpu_watcher;
-
+       static struct notifier_block xsn_cpu = {
+               .notifier_call = setup_cpu_watcher };
        register_xenstore_notifier(&xsn_cpu);
-
        return 0;
 }
 
@@ -1623,3 +1558,13 @@
        (void)HYPERVISOR_vcpu_op(VCPUOP_initialise, vcpu, &ctxt);
        (void)HYPERVISOR_vcpu_op(VCPUOP_up, vcpu, NULL);
 }
+
+/*
+ * Local variables:
+ *  c-file-style: "linux"
+ *  indent-tabs-mode: t
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ *  tab-width: 8
+ * End:
+ */

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