Hi
when I tried to hot plug a cpu on IBM bladecentre JS20 system,it dropped
in to xmon. On analyzing the problem,I found out that "self-stop" token
is not exported
to the OS through rtas(Could be verified by looking in to
/proc/device-tree/rtas file).
1:mon> e
cpu 0x1: Vector: 700 (Program Check) at [c00000000ff1bab0]
pc: c00000000001b144: .rtas_stop_self+0x34/0x70
lr: c0000000000439c0: .pSeries_mach_cpu_die+0x34/0x40
sp: c00000000ff1bd30
msr: 8000000000021032
current = 0xc00000000ff050b0
paca = 0xc0000000005ec500
pid = 0, comm = swapper
kernel BUG in rtas_stop_self at arch/powerpc/kernel/rtas.c:829!
===========================================
void rtas_stop_self(void)
{
struct rtas_args *rtas_args = &rtas_stop_self_args;
local_irq_disable();
BUG_ON(rtas_args->token == RTAS_UNKNOWN_SERVICE);
===================================================
#ifdef CONFIG_HOTPLUG_CPU
rtas_stop_self_args.token = rtas_token("stop-self");
#endif /* CONFIG_HOTPLUG_CPU */
#ifdef CONFIG_RTAS_ERROR_LOGGING
rtas_last_error_token = rtas_token("rtas-last-error");
===================================================
Since we are not supported by hardware for cpu hotplug. I have developed
the patch which will disable cpu hotplug on IBM bladecentre JS20.
Please let me know your comments on this please.
Signed-off-by: Srinivasa DS <[email protected]>
arch/powerpc/kernel/rtas.c | 3 +++
include/linux/cpu.h | 4 ++++
kernel/cpu.c | 24 ++++++++++++++++++++++--
3 files changed, 29 insertions(+), 2 deletions(-)
Index: linux-2.6.19-rc5/arch/powerpc/kernel/rtas.c
===================================================================
--- linux-2.6.19-rc5.orig/arch/powerpc/kernel/rtas.c 2006-11-08 07:54:20.000000000 +0530
+++ linux-2.6.19-rc5/arch/powerpc/kernel/rtas.c 2006-11-14 15:59:58.000000000 +0530
@@ -19,6 +19,7 @@
#include <linux/init.h>
#include <linux/capability.h>
#include <linux/delay.h>
+#include <linux/cpu.h>
#include <asm/prom.h>
#include <asm/rtas.h>
@@ -881,6 +882,8 @@
#ifdef CONFIG_HOTPLUG_CPU
rtas_stop_self_args.token = rtas_token("stop-self");
+ if(rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE)
+ disable_cpu_hotplug_perm();
#endif /* CONFIG_HOTPLUG_CPU */
#ifdef CONFIG_RTAS_ERROR_LOGGING
rtas_last_error_token = rtas_token("rtas-last-error");
Index: linux-2.6.19-rc5/kernel/cpu.c
===================================================================
--- linux-2.6.19-rc5.orig/kernel/cpu.c 2006-11-08 07:54:20.000000000 +0530
+++ linux-2.6.19-rc5/kernel/cpu.c 2006-11-14 16:06:17.000000000 +0530
@@ -63,6 +63,18 @@
}
EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
+void disable_cpu_hotplug_perm(void)
+{
+ mutex_lock(&cpu_add_remove_lock);
+ cpu_hotplug_disabled = PERM_DISABLED_CPU_HOTPLUG;
+ mutex_unlock(&cpu_add_remove_lock);
+}
+
+static int is_cpu_hotplug_perm_disabled()
+{
+ return cpu_hotplug_disabled == PERM_DISABLED_CPU_HOTPLUG;
+}
+
#endif /* CONFIG_HOTPLUG_CPU */
/* Need to know about CPUs going up/down? */
@@ -193,7 +205,7 @@
int err = 0;
mutex_lock(&cpu_add_remove_lock);
- if (cpu_hotplug_disabled)
+ if (cpu_hotplug_disabled || is_cpu_hotplug_perm_disabled())
err = -EBUSY;
else
err = _cpu_down(cpu);
@@ -244,7 +256,7 @@
int err = 0;
mutex_lock(&cpu_add_remove_lock);
- if (cpu_hotplug_disabled)
+ if (cpu_hotplug_disabled || is_cpu_hotplug_perm_disabled())
err = -EBUSY;
else
err = _cpu_up(cpu);
@@ -261,6 +273,10 @@
int cpu, first_cpu, error;
mutex_lock(&cpu_add_remove_lock);
+ if(is_cpu_hotplug_perm_disabled()) {
+ error = -EBUSY;
+ goto out;
+ }
first_cpu = first_cpu(cpu_present_map);
if (!cpu_online(first_cpu)) {
error = _cpu_up(first_cpu);
@@ -311,6 +327,10 @@
/* Allow everyone to use the CPU hotplug again */
mutex_lock(&cpu_add_remove_lock);
+ if(is_cpu_hotplug_perm_disabled()) {
+ mutex_unlock(&cpu_add_remove_lock);
+ return;
+ }
cpu_hotplug_disabled = 0;
mutex_unlock(&cpu_add_remove_lock);
Index: linux-2.6.19-rc5/include/linux/cpu.h
===================================================================
--- linux-2.6.19-rc5.orig/include/linux/cpu.h 2006-11-14 15:55:26.000000000 +0530
+++ linux-2.6.19-rc5/include/linux/cpu.h 2006-11-14 16:08:36.000000000 +0530
@@ -31,6 +31,8 @@
struct sys_device sysdev;
};
+#define PERM_DISABLED_CPU_HOTPLUG -1
+
extern int register_cpu(struct cpu *cpu, int num);
extern struct sys_device *get_cpu_sysdev(unsigned cpu);
#ifdef CONFIG_HOTPLUG_CPU
@@ -68,6 +70,7 @@
/* Stop CPUs going up and down. */
extern void lock_cpu_hotplug(void);
extern void unlock_cpu_hotplug(void);
+extern void disable_cpu_hotplug_perm(void);
#define hotcpu_notifier(fn, pri) { \
static struct notifier_block fn##_nb = \
{ .notifier_call = fn, .priority = pri }; \
@@ -80,6 +83,7 @@
#else
#define lock_cpu_hotplug() do { } while (0)
#define unlock_cpu_hotplug() do { } while (0)
+#define disable_cpu_hotplug_perm() do { } while (0)
#define lock_cpu_hotplug_interruptible() 0
#define hotcpu_notifier(fn, pri) do { } while (0)
#define register_hotcpu_notifier(nb) do { } while (0)
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