take3: Updated CPU Hotplug patches for IA64 (pj blessed) Patch [6/7]

[Ashok Raj <ashok.raj@intel.com>]

Name: cpu_present_map.patch
Author: Ashok Raj (Intel Corporation)
D: This patch adds cpu_present_map, cpu_present() and for_each_cpu_present()
D: to distinguish between possible cpu's in a system and cpu's physically
D: present in a system. Before cpu hotplug was introduced cpu_possible()
D: represented cpu's physically present in the system. With hotplug capable
D: Kernel, there is a requirement to distinguish a cpu as possible verses a 
D: CPU physically present in the system. This is required so that when
D: smp_init() attempts to start all cpu's it should now only attempt
D: to start cpu's present in the system. When a hotplug cpu is
D: physically inserted cpu_present_map will have bits updated
D: dynamically.


---

 linux-2.6.5-lhcs-root/arch/ia64/kernel/smpboot.c |   24 ++++++++++++-----------
 linux-2.6.5-lhcs-root/fs/proc/proc_misc.c        |    4 +--
 linux-2.6.5-lhcs-root/include/linux/cpumask.h    |   11 ++++++++++
 linux-2.6.5-lhcs-root/init/main.c                |    4 +--
 linux-2.6.5-lhcs-root/kernel/cpu.c               |   10 ++++++++-
 linux-2.6.5-lhcs-root/kernel/sched.c             |   11 ++++++++++
 6 files changed, 48 insertions(+), 16 deletions(-)

diff -puN arch/ia64/kernel/smpboot.c~cpu_present arch/ia64/kernel/smpboot.c
--- linux-2.6.5-lhcs/arch/ia64/kernel/smpboot.c~cpu_present	2004-05-03 16:31:35.000000000 -0700
+++ linux-2.6.5-lhcs-root/arch/ia64/kernel/smpboot.c	2004-05-04 07:08:23.255654034 -0700
@@ -75,11 +75,11 @@ extern unsigned long ia64_iobase;
 
 task_t *task_for_booting_cpu;
 
-/* Bitmask of currently online CPUs */
+/* Bitmasks of currently online, and possible CPUs */
 cpumask_t cpu_online_map;
 EXPORT_SYMBOL(cpu_online_map);
-cpumask_t phys_cpu_present_map;
-EXPORT_SYMBOL(phys_cpu_present_map);
+cpumask_t cpu_possible_map;
+EXPORT_SYMBOL(cpu_possible_map);
 
 /* which logical CPU number maps to which CPU (physical APIC ID) */
 volatile int ia64_cpu_to_sapicid[NR_CPUS];
@@ -99,6 +99,7 @@ static int __init
 nointroute (char *str)
 {
 	no_int_routing = 1;
+	printk ("no_int_routing on\n");
 	return 1;
 }
 
@@ -437,18 +438,17 @@ smp_build_cpu_map (void)
 	int sapicid, cpu, i;
 	int boot_cpu_id = hard_smp_processor_id();
 
-	for (cpu = 0; cpu < NR_CPUS; cpu++)
-		ia64_cpu_to_sapicid[cpu] = -1;
-
 	ia64_cpu_to_sapicid[0] = boot_cpu_id;
-	cpus_clear(phys_cpu_present_map);
-	cpu_set(0, phys_cpu_present_map);
 
+	cpus_clear(cpu_present_map);
+	cpu_set(0, cpu_present_map);
+	cpu_set(0, cpu_possible_map);
 	for (cpu = 1, i = 0; i < smp_boot_data.cpu_count; i++) {
 		sapicid = smp_boot_data.cpu_phys_id[i];
 		if (sapicid == boot_cpu_id)
 			continue;
-		cpu_set(cpu, phys_cpu_present_map);
+		cpu_set(cpu, cpu_present_map);
+		cpu_set(cpu, cpu_possible_map);
 		ia64_cpu_to_sapicid[cpu] = sapicid;
 		cpu++;
 	}
@@ -529,9 +529,11 @@ smp_prepare_cpus (unsigned int max_cpus)
 	if (!max_cpus) {
 		printk(KERN_INFO "SMP mode deactivated.\n");
 		cpus_clear(cpu_online_map);
-		cpus_clear(phys_cpu_present_map);
+		cpus_clear(cpu_present_map);
+		cpus_clear(cpu_possible_map);
 		cpu_set(0, cpu_online_map);
-		cpu_set(0, phys_cpu_present_map);
+		cpu_set(0, cpu_present_map);
+		cpu_set(0, cpu_possible_map);
 		return;
 	}
 }
diff -puN include/linux/cpumask.h~cpu_present include/linux/cpumask.h
--- linux-2.6.5-lhcs/include/linux/cpumask.h~cpu_present	2004-05-03 16:31:35.000000000 -0700
+++ linux-2.6.5-lhcs-root/include/linux/cpumask.h	2004-05-03 16:31:35.000000000 -0700
@@ -10,11 +10,15 @@
 
 extern cpumask_t cpu_online_map;
 extern cpumask_t cpu_possible_map;
+extern cpumask_t cpu_present_map;
 
 #define num_online_cpus()		cpus_weight(cpu_online_map)
 #define num_possible_cpus()		cpus_weight(cpu_possible_map)
+#define num_present_cpus()		cpus_weight(cpu_present_map)
+
 #define cpu_online(cpu)			cpu_isset(cpu, cpu_online_map)
 #define cpu_possible(cpu)		cpu_isset(cpu, cpu_possible_map)
+#define cpu_present(cpu)		cpu_isset(cpu, cpu_present_map)
 
 #define for_each_cpu_mask(cpu, mask)					\
 	for (cpu = first_cpu_const(mk_cpumask_const(mask));		\
@@ -23,16 +27,23 @@ extern cpumask_t cpu_possible_map;
 
 #define for_each_cpu(cpu) for_each_cpu_mask(cpu, cpu_possible_map)
 #define for_each_online_cpu(cpu) for_each_cpu_mask(cpu, cpu_online_map)
+#define for_each_present_cpu(cpu) for_each_cpu_mask(cpu, cpu_present_map)
 #else
 #define	cpu_online_map			cpumask_of_cpu(0)
 #define	cpu_possible_map		cpumask_of_cpu(0)
+#define	cpu_present_map			cpumask_of_cpu(0)
+
 #define num_online_cpus()		1
 #define num_possible_cpus()		1
+#define num_present_cpus()		1
+
 #define cpu_online(cpu)			({ BUG_ON((cpu) != 0); 1; })
 #define cpu_possible(cpu)		({ BUG_ON((cpu) != 0); 1; })
+#define cpu_present(cpu)		({ BUG_ON((cpu) != 0); 1; })
 
 #define for_each_cpu(cpu) for (cpu = 0; cpu < 1; cpu++)
 #define for_each_online_cpu(cpu) for (cpu = 0; cpu < 1; cpu++)
+#define for_each_present_cpu(cpu) for (cpu = 0; cpu < 1; cpu++)
 #endif
 
 #define cpumask_scnprintf(buf, buflen, map)				\
diff -puN init/main.c~cpu_present init/main.c
--- linux-2.6.5-lhcs/init/main.c~cpu_present	2004-05-03 16:31:35.000000000 -0700
+++ linux-2.6.5-lhcs-root/init/main.c	2004-05-03 16:31:35.000000000 -0700
@@ -357,10 +357,10 @@ static void __init smp_init(void)
 	unsigned j = 1;
 
 	/* FIXME: This should be done in userspace --RR */
-	for (i = 0; i < NR_CPUS; i++) {
+	for_each_present_cpu(i) {
 		if (num_online_cpus() >= max_cpus)
 			break;
-		if (cpu_possible(i) && !cpu_online(i)) {
+		if (!cpu_online(i)) {
 			cpu_up(i);
 			j++;
 		}
diff -puN kernel/cpu.c~cpu_present kernel/cpu.c
--- linux-2.6.5-lhcs/kernel/cpu.c~cpu_present	2004-05-03 16:31:35.000000000 -0700
+++ linux-2.6.5-lhcs-root/kernel/cpu.c	2004-05-03 16:31:35.000000000 -0700
@@ -20,6 +20,14 @@
 DECLARE_MUTEX(cpucontrol);
 
 static struct notifier_block *cpu_chain;
+/*
+ * Represents all cpu's present in the system
+ * In systems capable of hotplug, this map could dynamically grow
+ * as new cpu's are detected in the system via any platform specific
+ * method, such as ACPI for e.g.
+ */
+cpumask_t	cpu_present_map;
+EXPORT_SYMBOL(cpu_present_map);
 
 /* Need to know about CPUs going up/down? */
 int register_cpu_notifier(struct notifier_block *nb)
@@ -169,7 +177,7 @@ int __devinit cpu_up(unsigned int cpu)
 	if ((ret = down_interruptible(&cpucontrol)) != 0)
 		return ret;
 
-	if (cpu_online(cpu)) {
+	if (cpu_online(cpu) || !cpu_present(cpu)) {
 		ret = -EINVAL;
 		goto out;
 	}
diff -puN fs/proc/proc_misc.c~cpu_present fs/proc/proc_misc.c
--- linux-2.6.5-lhcs/fs/proc/proc_misc.c~cpu_present	2004-05-03 16:31:35.000000000 -0700
+++ linux-2.6.5-lhcs-root/fs/proc/proc_misc.c	2004-05-03 16:31:35.000000000 -0700
@@ -368,7 +368,7 @@ int show_stat(struct seq_file *p, void *
 	if (wall_to_monotonic.tv_nsec)
 		--jif;
 
-	for_each_cpu(i) {
+	for_each_online_cpu(i) {
 		int j;
 
 		user += kstat_cpu(i).cpustat.user;
@@ -390,7 +390,7 @@ int show_stat(struct seq_file *p, void *
 		(unsigned long long)jiffies_64_to_clock_t(iowait),
 		(unsigned long long)jiffies_64_to_clock_t(irq),
 		(unsigned long long)jiffies_64_to_clock_t(softirq));
-	for_each_cpu(i) {
+	for_each_online_cpu(i) {
 
 		/* Copy values here to work around gcc-2.95.3, gcc-2.96 */
 		user = kstat_cpu(i).cpustat.user;
diff -puN kernel/sched.c~cpu_present kernel/sched.c
--- linux-2.6.5-lhcs/kernel/sched.c~cpu_present	2004-05-03 16:31:35.000000000 -0700
+++ linux-2.6.5-lhcs-root/kernel/sched.c	2004-05-03 17:51:57.000000000 -0700
@@ -2934,6 +2934,17 @@ void __init sched_init(void)
 	runqueue_t *rq;
 	int i, j, k;
 
+	/*
+	 * If arch is not hotplug ready and did not populate
+	 * cpu_present_map, just make cpu_present_map same as cpu_possible_map
+	 * for other cpu bringup code to function as normal. e.g smp_init() etc.
+	 */
+	if (cpus_empty(cpu_present_map)) {
+		for_each_cpu(i) {
+			cpu_set(i, cpu_present_map);
+		}
+	}
+
 	for (i = 0; i < NR_CPUS; i++) {
 		prio_array_t *array;
 

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