2.5.25 Hotplug CPU boot changes

diff -urN -I $.*$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/include/linux/notifier.h working-2.5.25-hotcpu/include/linux/notifier.h
@@ -58,5 +58,7 @@
 #define SYS_HALT	0x0002	/* Notify of system halt */
 #define SYS_POWER_OFF	0x0003	/* Notify of system power off */
 
+#define CPU_ONLINE	0x0002 /* CPU (unsigned)v coming up */
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_NOTIFIER_H */

diff -urN -I $.*$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/include/linux/sched.h working-2.5.25-hotcpu/include/linux/sched.h
@@ -150,7 +150,6 @@
 extern void update_one_process(struct task_struct *p, unsigned long user,
 			       unsigned long system, int cpu);
 extern void scheduler_tick(int user_tick, int system);
-extern void migration_init(void);
 extern unsigned long cache_decay_ticks;
 
 

diff -urN -I $.*$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/include/linux/smp.h working-2.5.25-hotcpu/include/linux/smp.h
@@ -32,19 +32,19 @@
 
 
 /*
- * Boot processor call to load the other CPU's
+ * Prepare machine for booting other CPUs.
  */
-extern void smp_boot_cpus(void);
+extern void smp_prepare_cpus(unsigned int max_cpus);
 
 /*
- * Processor call in. Must hold processors until ..
+ * Bring a CPU up
  */
-extern void smp_callin(void);
+extern int __cpu_up(unsigned int cpunum);
 
 /*
- * Multiprocessors may now schedule
+ * Final polishing of CPUs
  */
-extern void smp_commence(void);
+extern void smp_cpus_done(unsigned int max_cpus);
 
 /*
  * Call a function on all other processors

@@ -71,6 +71,13 @@
 #define MSG_RESCHEDULE		0x0003	/* Reschedule request from master CPU*/
 #define MSG_CALL_FUNCTION       0x0004  /* Call function on all other CPUs */
 
+struct notifier_block;
+
+/* Need to know about CPUs going up/down? */
+extern int register_cpu_notifier(struct notifier_block *nb);
+extern void unregister_cpu_notifier(struct notifier_block *nb);
+
+int cpu_up(unsigned int cpu);
 #else /* !SMP */
 
 /*

@@ -92,6 +99,10 @@
 #define __per_cpu_data
 #define per_cpu(var, cpu)			var
 #define this_cpu(var)				var
+
+/* Need to know about CPUs going up/down? */
+#define register_cpu_notifier(nb) 0
+#define unregister_cpu_notifier(nb) do { } while(0)
 
 #endif /* !SMP */
 

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diff -urN -I $.*$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/kernel/softirq.c working-2.5.25-hotcpu/kernel/softirq.c
@@ -17,6 +17,7 @@
 #include <linux/init.h>
 #include <linux/tqueue.h>
 #include <linux/percpu.h>
+#include <linux/notifier.h>
 
 /*
    - No shared variables, all the data are CPU local.

@@ -397,20 +398,32 @@
 	}
 }
 
-static __init int spawn_ksoftirqd(void)
+static int __devinit cpu_callback(struct notifier_block *nfb,
+				  unsigned long action,
+				  void *hcpu)
 {
-	int cpu;
+	int hotcpu = (unsigned long)hcpu;
 
-	for (cpu = 0; cpu < NR_CPUS; cpu++) {
-		if (!cpu_online(cpu))
-			continue;
-		if (kernel_thread(ksoftirqd, (void *) (long) cpu,
-				  CLONE_FS | CLONE_FILES | CLONE_SIGNAL) < 0)
-			printk("spawn_ksoftirqd() failed for cpu %dn", cpu);
-		else
-			while (!ksoftirqd_task(cpu))
-				yield();
-	}
+	if (action == CPU_ONLINE) {
+		if (kernel_thread(ksoftirqd, hcpu,
+				  CLONE_FS | CLONE_FILES | CLONE_SIGNAL) < 0) {
+			printk("ksoftirqd for %i failedn", hotcpu);
+			return NOTIFY_BAD;
+		}
+
+		while (!ksoftirqd_task(hotcpu))
+			yield();
+		return NOTIFY_OK;
+ 	}
+	return NOTIFY_BAD;
+}
+
+static struct notifier_block cpu_nfb = { &cpu_callback, NULL, 0 };
+
+static __init int spawn_ksoftirqd(void)
+{
+	cpu_callback(&cpu_nfb, CPU_ONLINE, (void *)smp_processor_id());
+	register_cpu_notifier(&cpu_nfb);
 	return 0;
 }
 

diff -urN -I $.*$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/arch/i386/kernel/apic.c working-2.5.25-hotcpu/arch/i386/kernel/apic.c
@@ -798,9 +798,9 @@
 	apic_write_around(APIC_TMICT, clocks/APIC_DIVISOR);
 }
 
-void setup_APIC_timer(void * data)
+static void setup_APIC_timer(unsigned int clocks)
 {
-	unsigned int clocks = (unsigned int) data, slice, t0, t1;
+	unsigned int slice, t0, t1;
 	unsigned long flags;
 	int delta;
 

@@ -926,7 +926,7 @@
 
 int dont_use_local_apic_timer __initdata = 0;
 
-void __init setup_APIC_clocks (void)
+void __init setup_boot_APIC_clock(void)
 {
 	/* Disabled by DMI scan or kernel option? */
 	if (dont_use_local_apic_timer)

@@ -941,12 +941,16 @@
 	/*
 	 * Now set up the timer for real.
 	 */
-	setup_APIC_timer((void *)calibration_result);
+	setup_APIC_timer(calibration_result);
 
 	__sti();
+}
 
-	/* and update all other cpus */
-	smp_call_function(setup_APIC_timer, (void *)calibration_result, 1, 1);
+void __init setup_secondary_APIC_clock(void)
+{
+	__cli(); /* FIXME: Do we need this? --RR */
+	setup_APIC_timer(calibration_result);
+	__sti();
 }
 
 void __init disable_APIC_timer(void)

@@ -1178,7 +1182,7 @@
 		if (!skip_ioapic_setup && nr_ioapics)
 			setup_IO_APIC();
 #endif
-	setup_APIC_clocks();
+	setup_boot_APIC_clock();
 
 	return 0;
 }

diff -urN -I $.*$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/arch/i386/kernel/apm.c working-2.5.25-hotcpu/arch/i386/kernel/apm.c
@@ -1587,7 +1587,7 @@
 
 	p = buf;
 
-	if ((num_online_cpus() == 1) &&
+	if ((num_possible_cpus() == 1) &&
 	    !(error = apm_get_power_status(&bx, &cx, &dx))) {
 		ac_line_status = (bx >> 8) & 0xff;
 		battery_status = bx & 0xff;

@@ -1718,7 +1718,7 @@
 		}
 	}
 
-	if (debug && (num_online_cpus() == 1)) {
+	if (debug && (num_possible_cpus() == 1)) {
 		error = apm_get_power_status(&bx, &cx, &dx);
 		if (error)
 			printk(KERN_INFO "apm: power status not availablen");

@@ -1762,7 +1762,7 @@
 		pm_power_off = apm_power_off;
 	register_sysrq_key('o', &sysrq_poweroff_op);
 
-	if (num_online_cpus() == 1) {
+	if (num_possible_cpus() == 1) {
 #if defined(CONFIG_APM_DISPLAY_BLANK) && defined(CONFIG_VT)
 		console_blank_hook = apm_console_blank;
 #endif

@@ -1905,9 +1905,7 @@
 		printk(KERN_NOTICE "apm: disabled on user request.n");
 		return -ENODEV;
 	}
-	/* FIXME: When boot code changes, this will need to be
-           deactivated when/if a CPU comes up --RR */
-	if ((num_online_cpus() > 1) && !power_off) {
+	if ((num_possible_cpus() > 1) && !power_off) {
 		printk(KERN_NOTICE "apm: disabled - APM is not SMP safe.n");
 		return -ENODEV;
 	}

@@ -1961,9 +1959,7 @@
 
 	kernel_thread(apm, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND | SIGCHLD);
 
-	/* FIXME: When boot code changes, this will need to be
-           deactivated when/if a CPU comes up --RR */
-	if (num_online_cpus() > 1) {
+	if (num_possible_cpus() > 1) {
 		printk(KERN_NOTICE
 		   "apm: disabled - APM is not SMP safe (power off active).n");
 		return 0;

diff -urN -I $.*$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/arch/i386/kernel/mtrr.c working-2.5.25-hotcpu/arch/i386/kernel/mtrr.c
@@ -1055,7 +1055,7 @@
     wait_barrier_cache_disable = TRUE;
     wait_barrier_execute = TRUE;
     wait_barrier_cache_enable = TRUE;
-    atomic_set (&undone_count, num_online_cpus() - 1);
+    atomic_set (&undone_count, num_booting_cpus() - 1);
     /*  Start the ball rolling on other CPUs  */
     if (smp_call_function (ipi_handler, &data, 1, 0) != 0)
 	panic ("mtrr: timed out waiting for other CPUsn");

@@ -1064,14 +1064,14 @@
     /*  Wait for all other CPUs to flush and disable their caches  */
     while (atomic_read (&undone_count) > 0) { rep_nop(); barrier(); }
     /* Set up for completion wait and then release other CPUs to change MTRRs*/
-    atomic_set (&undone_count, num_online_cpus() - 1);
+    atomic_set (&undone_count, num_booting_cpus() - 1);
     wait_barrier_cache_disable = FALSE;
     set_mtrr_cache_disable (&ctxt);
 
     /*  Wait for all other CPUs to flush and disable their caches  */
     while (atomic_read (&undone_count) > 0) { rep_nop(); barrier(); }
     /* Set up for completion wait and then release other CPUs to change MTRRs*/
-    atomic_set (&undone_count, num_online_cpus() - 1);
+    atomic_set (&undone_count, num_booting_cpus() - 1);
     wait_barrier_execute = FALSE;
     (*set_mtrr_up) (reg, base, size, type, FALSE);
     /*  Now wait for other CPUs to complete the function  */

diff -urN -I $.*$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/arch/i386/kernel/nmi.c working-2.5.25-hotcpu/arch/i386/kernel/nmi.c
@@ -81,6 +81,8 @@
 	sti();
 	mdelay((10*1000)/nmi_hz); // wait 10 ticks
 
+	/* FIXME: Only boot CPU is online at this stage.  Check CPUs
+           as they come up. */
 	for (cpu = 0; cpu < NR_CPUS; cpu++) {
 		if (!cpu_online(cpu))
 			continue;

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diff -urN -I $.*$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/include/asm-i386/apic.h working-2.5.25-hotcpu/include/asm-i386/apic.h
@@ -76,7 +76,8 @@
 extern void setup_local_APIC (void);
 extern void init_apic_mappings (void);
 extern void smp_local_timer_interrupt (struct pt_regs * regs);
-extern void setup_APIC_clocks (void);
+extern void setup_boot_APIC_clock (void);
+extern void setup_secondary_APIC_clock (void);
 extern void setup_apic_nmi_watchdog (void);
 extern inline void nmi_watchdog_tick (struct pt_regs * regs);
 extern int APIC_init_uniprocessor (void);

diff -urN -I $.*$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/include/asm-i386/smp.h working-2.5.25-hotcpu/include/asm-i386/smp.h
@@ -79,19 +79,13 @@
 extern volatile int logical_apicid_to_cpu[MAX_APICID];
 
 /*
- * General functions that each host system must provide.
- */
- 
-extern void smp_boot_cpus(void);
-extern void smp_store_cpu_info(int id);		/* Store per CPU info (like the initial udelay numbers */
-
-/*
  * This function is needed by all SMP systems. It must _always_ be valid
  * from the initial startup. We map APIC_BASE very early in page_setup(),
  * so this is correct in the x86 case.
  */
 #define smp_processor_id() (current_thread_info()->cpu)
 
+#define cpu_possible(cpu) (phys_cpu_present_map & (1<<(cpu)))
 #define cpu_online(cpu) (cpu_online_map & (1<<(cpu)))
 
 extern inline unsigned int num_online_cpus(void)

@@ -117,6 +111,13 @@
 {
 	/* we don't want to mark this access volatile - bad code generation */
 	return GET_APIC_LOGICAL_ID(*(unsigned long *)(APIC_BASE+APIC_LDR));
+}
+
+extern volatile unsigned long cpu_callout_map;
+/* We don't mark CPUs online until __cpu_up(), so we need another measure */
+static inline int num_booting_cpus(void)
+{
+	return hweight32(cpu_callout_map);
 }
 
 #endif /* !__ASSEMBLY__ */