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Subject[PATCH][5/6] CPU Hotplug i386
 arch/i386/kernel/process.c |   39 ++++++++++++++++++++++++++++--
arch/i386/kernel/smp.c | 18 +++++++++++--
arch/i386/kernel/smpboot.c | 58 +++++++++++++++++++++++++++++++++++++++++----
include/asm-i386/smp.h | 4 +++
4 files changed, 110 insertions(+), 9 deletions(-)

Index: linux-2.5.59-lch2/include/asm-i386/smp.h
===================================================================
RCS file: /build/cvsroot/linux-2.5.59/include/asm-i386/smp.h,v
retrieving revision 1.1.1.1
retrieving revision 1.1.1.1.2.1
diff -u -r1.1.1.1 -r1.1.1.1.2.1
--- linux-2.5.59-lch2/include/asm-i386/smp.h 17 Jan 2003 11:16:10 -0000 1.1.1.1
+++ linux-2.5.59-lch2/include/asm-i386/smp.h 20 Jan 2003 13:48:27 -0000 1.1.1.1.2.1
@@ -100,6 +100,10 @@
}

#endif
+
+extern int __cpu_disable(void);
+extern void __cpu_die(unsigned int cpu);
+
#endif /* !__ASSEMBLY__ */

#define NO_PROC_ID 0xFF /* No processor magic marker */
Index: linux-2.5.59-lch2/arch/i386/kernel/process.c
===================================================================
RCS file: /build/cvsroot/linux-2.5.59/arch/i386/kernel/process.c,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 process.c
--- linux-2.5.59-lch2/arch/i386/kernel/process.c 17 Jan 2003 11:14:42 -0000 1.1.1.1
+++ linux-2.5.59-lch2/arch/i386/kernel/process.c 20 Jan 2003 14:24:35 -0000
@@ -36,7 +36,7 @@
#include <linux/mc146818rtc.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
-
+#include <linux/brlock.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
@@ -46,6 +46,7 @@
#include <asm/i387.h>
#include <asm/irq.h>
#include <asm/desc.h>
+#include <asm/tlbflush.h>
#ifdef CONFIG_MATH_EMULATION
#include <asm/math_emu.h>
#endif
@@ -80,6 +81,8 @@
hlt_counter--;
}

+DECLARE_PER_CPU(int, cpu_die);
+
/*
* We use this if we don't have any better
* idle routine..
@@ -127,6 +130,36 @@
}
}

+#ifdef CONFIG_HOTPLUG
+static inline void maybe_play_dead(void)
+{
+ if (unlikely(__get_cpu_var(cpu_die))) {
+ printk("Cpu %u Dust Dust Dust\n", smp_processor_id());
+ /* Ack it */
+ __get_cpu_var(cpu_die) = 2;
+
+ /* Death loop */
+ local_irq_disable();
+ while (__get_cpu_var(cpu_die))
+ cpu_relax();
+ local_irq_enable();
+
+ /* Now, we missed any cache flush IPIs, so be safe. */
+ local_flush_tlb();
+
+ /* Ack it by setting online bit */
+ br_write_lock_irq(BR_CPU_LOCK);
+ set_bit(smp_processor_id(), &cpu_online_map);
+ br_write_unlock_irq(BR_CPU_LOCK);
+ printk("Cpu %u arisen\n", smp_processor_id());
+ }
+}
+#else
+static inline void maybe_play_dead(void)
+{
+}
+#endif /*CONFIG_HOTPLUG*/
+
/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
@@ -141,8 +174,10 @@
if (!idle)
idle = default_idle;
irq_stat[smp_processor_id()].idle_timestamp = jiffies;
- while (!need_resched())
+ while (!need_resched()) {
+ maybe_play_dead();
idle();
+ }
schedule();
}
}
Index: linux-2.5.59-lch2/arch/i386/kernel/smp.c
===================================================================
RCS file: /build/cvsroot/linux-2.5.59/arch/i386/kernel/smp.c,v
retrieving revision 1.1.1.1
retrieving revision 1.1.1.1.2.1
diff -u -r1.1.1.1 -r1.1.1.1.2.1
--- linux-2.5.59-lch2/arch/i386/kernel/smp.c 17 Jan 2003 11:14:42 -0000 1.1.1.1
+++ linux-2.5.59-lch2/arch/i386/kernel/smp.c 20 Jan 2003 13:48:26 -0000 1.1.1.1.2.1
@@ -19,6 +19,7 @@
#include <linux/mc146818rtc.h>
#include <linux/cache.h>
#include <linux/interrupt.h>
+#include <linux/brlock.h>

#include <asm/mtrr.h>
#include <asm/pgalloc.h>
@@ -350,13 +351,18 @@
*/
if (!cpumask)
BUG();
- if ((cpumask & cpu_online_map) != cpumask)
+ if ((cpumask & cpu_callout_map) != cpumask)
BUG();
if (cpumask & (1 << smp_processor_id()))
BUG();
if (!mm)
BUG();

+ /* CPUs might have gone offline: don't worry about them. */
+ cpumask &= cpu_online_map;
+ if (!cpumask)
+ return;
+
/*
* i'm not happy about this global shared spinlock in the
* MM hot path, but we'll see how contended it is.
@@ -515,10 +521,15 @@
*/
{
struct call_data_struct data;
- int cpus = num_online_cpus()-1;
+ int cpus;

- if (!cpus)
+ br_read_lock(BR_CPU_LOCK);
+ cpus = num_online_cpus()-1;
+
+ if (!cpus) {
+ br_read_unlock(BR_CPU_LOCK);
return 0;
+ }

data.func = func;
data.info = info;
@@ -542,6 +553,7 @@
barrier();
spin_unlock(&call_lock);

+ br_read_unlock(BR_CPU_LOCK);
return 0;
}

Index: linux-2.5.59-lch2/arch/i386/kernel/smpboot.c
===================================================================
RCS file: /build/cvsroot/linux-2.5.59/arch/i386/kernel/smpboot.c,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 smpboot.c
--- linux-2.5.59-lch2/arch/i386/kernel/smpboot.c 17 Jan 2003 11:14:42 -0000 1.1.1.1
+++ linux-2.5.59-lch2/arch/i386/kernel/smpboot.c 3 Feb 2003 11:19:12 -0000
@@ -45,6 +45,8 @@

#include <linux/delay.h>
#include <linux/mc146818rtc.h>
+#include <linux/brlock.h>
+#include <linux/percpu.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/desc.h>
@@ -64,9 +66,10 @@
/* Bitmask of currently online CPUs */
unsigned long cpu_online_map;

-static volatile unsigned long cpu_callin_map;
+/* Initialize, although master cpu never calls in */
+static volatile unsigned long cpu_callin_map = 1;
volatile unsigned long cpu_callout_map;
-static unsigned long smp_commenced_mask;
+static unsigned long smp_commenced_mask = 1;

/* Per CPU bogomips and other parameters */
struct cpuinfo_x86 cpu_data[NR_CPUS] __cacheline_aligned;
@@ -222,6 +225,8 @@
int buggy = 0;

printk("checking TSC synchronization across %u CPUs: ", num_booting_cpus());
+ if (fast_gettimeoffset_quotient == 0)
+ fast_gettimeoffset_quotient = 1<<30;

one_usec = ((1<<30)/fast_gettimeoffset_quotient)*(1<<2);

@@ -458,7 +463,9 @@
* the local TLBs too.
*/
local_flush_tlb();
+ br_write_lock_irq(BR_CPU_LOCK);
set_bit(smp_processor_id(), &cpu_online_map);
+ br_write_unlock_irq(BR_CPU_LOCK);
wmb();
return cpu_idle();
}
@@ -1138,10 +1145,11 @@
set_bit(smp_processor_id(), &cpu_callout_map);
}

+DEFINE_PER_CPU(int, cpu_die) = { 0 };
+
int __devinit __cpu_up(unsigned int cpu)
{
- /* This only works at boot for x86. See "rewrite" above. */
- if (test_bit(cpu, &smp_commenced_mask)) {
+ if (test_bit(cpu, &smp_commenced_mask) && cpu_online(cpu)) {
local_irq_enable();
return -ENOSYS;
}
@@ -1152,12 +1160,54 @@
return -EIO;
}

+ /* Already up, and in maybe_play_dead now? */
+ if (test_bit(cpu, &smp_commenced_mask)) {
+ per_cpu(cpu_die, cpu) = 0;
+ wmb();
+ wake_idle_cpu(cpu);
+ while (!cpu_online(cpu))
+ yield();
+ printk("Cpu %u says it's online\n", cpu);
+ return 0;
+ }
+
local_irq_enable();
/* Unleash the CPU! */
set_bit(cpu, &smp_commenced_mask);
while (!test_bit(cpu, &cpu_online_map))
mb();
return 0;
+}
+
+int __cpu_disable(void)
+{
+ br_write_lock_irq(BR_CPU_LOCK);
+ cpu_online_map &= ~(1UL << smp_processor_id());
+ br_write_unlock_irq(BR_CPU_LOCK);
+
+ printk("Disabled cpu %u\n", smp_processor_id());
+ return 0;
+}
+
+void __cpu_die(unsigned int cpu)
+{
+ unsigned int start;
+
+ /* Final threads can take some time to actually clean up */
+ while (!idle_cpu(cpu))
+ yield();
+
+ /* FIXME: Rebind interrupts which have affinity. --RR */
+ per_cpu(cpu_die, cpu) = 1;
+ wmb();
+ for (start = jiffies; time_before(jiffies, start + HZ); ) {
+ wake_idle_cpu(cpu);
+ /* They ack this in maybe_play_dead by incrementing it. */
+ if (per_cpu(cpu_die, cpu) == 2)
+ return;
+ yield();
+ }
+ printk(KERN_ERR "CPU %u didn't die...\n", cpu);
}

void __init smp_cpus_done(unsigned int max_cpus)

-
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