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

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

Hi Andrew/DavidM

as i mentioned earlier, i broke the smp build for i386 in the take3 patches i sent this morning.
This patch is tested on i386 and ia64 as well.


thanks to Anil Keshavamurthy for taking initiative to test and bringup the issue.

Cheers,
Ashok


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 thta 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-2.6.6-rc3-root/arch/ia64/kernel/smpboot.c |   22 +++++++++++++---------
 linux-2.6.6-rc3-root/fs/buffer.c                |    2 +-
 linux-2.6.6-rc3-root/fs/proc/proc_misc.c        |    4 ++--
 linux-2.6.6-rc3-root/include/asm-ia64/smp.h     |    3 ---
 linux-2.6.6-rc3-root/include/linux/cpumask.h    |   11 +++++++++++
 linux-2.6.6-rc3-root/init/main.c                |    4 ++--
 linux-2.6.6-rc3-root/kernel/cpu.c               |   10 +++++++++-
 linux-2.6.6-rc3-root/kernel/fork.c              |    2 +-
 linux-2.6.6-rc3-root/kernel/sched.c             |   17 ++++++++++++++---
 linux-2.6.6-rc3-root/kernel/timer.c             |    2 +-
 10 files changed, 54 insertions(+), 23 deletions(-)

diff -puN arch/ia64/kernel/smpboot.c~cpu_present arch/ia64/kernel/smpboot.c
--- linux-2.6.6-rc3/arch/ia64/kernel/smpboot.c~cpu_present	2004-05-04 13:33:45.000000000 -0700
+++ linux-2.6.6-rc3-root/arch/ia64/kernel/smpboot.c	2004-05-04 15:00:35.302427934 -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;
 }
 
@@ -441,14 +442,15 @@ smp_build_cpu_map (void)
 		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 +531,11 @@ 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-2.6.6-rc3/include/linux/cpumask.h~cpu_present	2004-05-04 13:33:45.000000000 -0700
+++ linux-2.6.6-rc3-root/include/linux/cpumask.h	2004-05-04 13:33:45.000000000 -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-2.6.6-rc3/init/main.c~cpu_present	2004-05-04 13:33:45.000000000 -0700
+++ linux-2.6.6-rc3-root/init/main.c	2004-05-04 13:33:45.000000000 -0700
@@ -354,10 +354,10 @@ 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-2.6.6-rc3/kernel/cpu.c~cpu_present	2004-05-04 13:33:45.000000000 -0700
+++ linux-2.6.6-rc3-root/kernel/cpu.c	2004-05-04 13:33:45.000000000 -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-2.6.6-rc3/fs/proc/proc_misc.c~cpu_present	2004-05-04 13:33:45.000000000 -0700
+++ linux-2.6.6-rc3-root/fs/proc/proc_misc.c	2004-05-04 13:33:45.000000000 -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-2.6.6-rc3/kernel/sched.c~cpu_present	2004-05-04 13:33:45.000000000 -0700
+++ linux-2.6.6-rc3-root/kernel/sched.c	2004-05-04 13:41:48.000000000 -0700
@@ -945,7 +945,7 @@ unsigned long nr_uninterruptible(void)
 {
 	unsigned long i, sum = 0;
 
-	for_each_cpu(i)
+	for_each_online_cpu(i)
 		sum += cpu_rq(i)->nr_uninterruptible;
 
 	return sum;
@@ -955,7 +955,7 @@ unsigned long long nr_context_switches(v
 {
 	unsigned long long i, sum = 0;
 
-	for_each_cpu(i)
+	for_each_online_cpu(i)
 		sum += cpu_rq(i)->nr_switches;
 
 	return sum;
@@ -965,7 +965,7 @@ unsigned long nr_iowait(void)
 {
 	unsigned long i, sum = 0;
 
-	for_each_cpu(i)
+	for_each_online_cpu(i)
 		sum += atomic_read(&cpu_rq(i)->nr_iowait);
 
 	return sum;
@@ -2944,6 +2944,17 @@ 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;
 
diff -puN fs/buffer.c~cpu_present fs/buffer.c
--- linux-2.6.6-rc3/fs/buffer.c~cpu_present	2004-05-04 13:38:00.000000000 -0700
+++ linux-2.6.6-rc3-root/fs/buffer.c	2004-05-04 13:39:05.000000000 -0700
@@ -2966,7 +2966,7 @@ static void recalc_bh_state(void)
 	if (__get_cpu_var(bh_accounting).ratelimit++ < 4096)
 		return;
 	__get_cpu_var(bh_accounting).ratelimit = 0;
-	for_each_cpu(i)
+	for_each_online_cpu(i)
 		tot += per_cpu(bh_accounting, i).nr;
 	buffer_heads_over_limit = (tot > max_buffer_heads);
 }
diff -puN kernel/fork.c~cpu_present kernel/fork.c
--- linux-2.6.6-rc3/kernel/fork.c~cpu_present	2004-05-04 13:40:01.000000000 -0700
+++ linux-2.6.6-rc3-root/kernel/fork.c	2004-05-04 13:40:11.000000000 -0700
@@ -60,7 +60,7 @@ int nr_processes(void)
 	int cpu;
 	int total = 0;
 
-	for_each_cpu(cpu)
+	for_each_online_cpu(cpu)
 		total += per_cpu(process_counts, cpu);
 
 	return total;
diff -puN kernel/timer.c~cpu_present kernel/timer.c
--- linux-2.6.6-rc3/kernel/timer.c~cpu_present	2004-05-04 13:42:55.000000000 -0700
+++ linux-2.6.6-rc3-root/kernel/timer.c	2004-05-04 13:43:09.000000000 -0700
@@ -332,7 +332,7 @@ int del_timer_sync(struct timer_list *ti
 del_again:
 	ret += del_timer(timer);
 
-	for_each_cpu(i) {
+	for_each_online_cpu(i) {
 		base = &per_cpu(tvec_bases, i);
 		if (base->running_timer == timer) {
 			while (base->running_timer == timer) {
diff -puN include/asm-ia64/smp.h~cpu_present include/asm-ia64/smp.h
--- linux-2.6.6-rc3/include/asm-ia64/smp.h~cpu_present	2004-05-04 15:01:31.992886647 -0700
+++ linux-2.6.6-rc3-root/include/asm-ia64/smp.h	2004-05-04 15:02:04.318098510 -0700
@@ -38,7 +38,6 @@ extern struct smp_boot_data {
 
 extern char no_int_routing __devinitdata;
 
-extern cpumask_t phys_cpu_present_map;
 extern cpumask_t cpu_online_map;
 extern unsigned long ipi_base_addr;
 extern unsigned char smp_int_redirect;
@@ -48,8 +47,6 @@ extern volatile int ia64_cpu_to_sapicid[
 
 extern unsigned long ap_wakeup_vector;
 
-#define cpu_possible_map phys_cpu_present_map
-
 /*
  * Function to map hard smp processor id to logical id.  Slow, so don't use this in
  * performance-critical code.

_