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SubjectRe: [patch 1/8] Processor degredation support.
On Wed, Mar 28, 2007 at 08:41:45AM +0000, Pavel Machek wrote:
> On Wed 2007-03-28 08:54:43, Heiko Carstens wrote:
> > > > +++ linux-2.6/drivers/s390/char/sclp_confmgm.c
> > >
> > > Can we get less cyptic name?
> >
> > Would you like to see sclp_configuration_management.c?
>
> No, but maybe sclp_manager.c or sclp_config.c?
>
>
> > > > +static void sclp_conf_receiver_fn(struct evbuf_header *evbuf)
> > > > +{
> > > > + struct conf_mgm_data *cdata;
> > > > +
> > > > + cdata = (struct conf_mgm_data *)(evbuf + 1);
> > > > + if (cdata->ev_qualifier == EV_QUAL_CAP_CHANGE)
> > > > + /* Will be parsed. Don't change. */
> > > > + printk(KERN_WARNING "sclp: CPU capability changed.\n");
> > > > +}
> > >
> > > What's that? I do not think printk provides guaranteed delivery.
> >
> > True. But which generic interface is currently used to notify user space
> > of state changes? Maybe a uevent for the cpu device..
>
> Maybe.

Thanks for reviewing and your comments!
So how about the patch below? I think it addresses all your objections.

Subject: [PATCH] Processor degredation support.

From: Heiko Carstens <heiko.carstens@de.ibm.com>

Generate uevents for all cpus if cpu capability changes. This can
happen e.g. because the cpus are overheating. The cpu capability can
be read via /sys/devices/system/cpu/cpuN/capability.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
---

arch/s390/kernel/smp.c | 48 +++++++++++++++++++++++--
drivers/s390/char/Makefile | 2 -
drivers/s390/char/sclp.h | 2 +
drivers/s390/char/sclp_config.c | 74 ++++++++++++++++++++++++++++++++++++++++
drivers/s390/sysinfo.c | 18 +++++++++
include/asm-s390/processor.h | 1
6 files changed, 139 insertions(+), 6 deletions(-)

diff -urpN linux-2.6/arch/s390/kernel/smp.c linux-2.6-patched/arch/s390/kernel/smp.c
--- linux-2.6/arch/s390/kernel/smp.c 2007-04-02 18:11:11.000000000 +0200
+++ linux-2.6-patched/arch/s390/kernel/smp.c 2007-04-02 18:11:20.000000000 +0200
@@ -821,19 +821,57 @@ int setup_profiling_timer(unsigned int m

static DEFINE_PER_CPU(struct cpu, cpu_devices);

+static ssize_t show_capability(struct sys_device *dev, char *buf)
+{
+ unsigned int capability;
+ int rc;
+
+ rc = get_cpu_capability(&capability);
+ if (rc)
+ return rc;
+ return sprintf(buf, "%u\n", capability);
+}
+static SYSDEV_ATTR(capability, 0444, show_capability, NULL);
+
+static int __cpuinit smp_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (unsigned int)(long)hcpu;
+ struct cpu *c = &per_cpu(cpu_devices, cpu);
+ struct sys_device *s = &c->sysdev;
+
+ switch (action) {
+ case CPU_ONLINE:
+ if (sysdev_create_file(s, &attr_capability))
+ return NOTIFY_BAD;
+ break;
+ case CPU_DEAD:
+ sysdev_remove_file(s, &attr_capability);
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata smp_cpu_nb = {
+ .notifier_call = smp_cpu_notify,
+};
+
static int __init topology_init(void)
{
int cpu;
- int ret;
+
+ register_cpu_notifier(&smp_cpu_nb);

for_each_possible_cpu(cpu) {
struct cpu *c = &per_cpu(cpu_devices, cpu);
+ struct sys_device *s = &c->sysdev;

c->hotpluggable = 1;
- ret = register_cpu(c, cpu);
- if (ret)
- printk(KERN_WARNING "topology_init: register_cpu %d "
- "failed (%d)\n", cpu, ret);
+ register_cpu(c, cpu);
+ if (!cpu_online(cpu))
+ continue;
+ s = &c->sysdev;
+ sysdev_create_file(s, &attr_capability);
}
return 0;
}
diff -urpN linux-2.6/drivers/s390/char/Makefile linux-2.6-patched/drivers/s390/char/Makefile
--- linux-2.6/drivers/s390/char/Makefile 2007-04-02 18:11:11.000000000 +0200
+++ linux-2.6-patched/drivers/s390/char/Makefile 2007-04-02 18:11:20.000000000 +0200
@@ -3,7 +3,7 @@
#

obj-y += ctrlchar.o keyboard.o defkeymap.o sclp.o sclp_rw.o sclp_quiesce.o \
- sclp_info.o sclp_chp.o
+ sclp_info.o sclp_config.o sclp_chp.o

obj-$(CONFIG_TN3270) += raw3270.o
obj-$(CONFIG_TN3270_CONSOLE) += con3270.o
diff -urpN linux-2.6/drivers/s390/char/sclp_config.c linux-2.6-patched/drivers/s390/char/sclp_config.c
--- linux-2.6/drivers/s390/char/sclp_config.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6-patched/drivers/s390/char/sclp_config.c 2007-04-02 18:11:20.000000000 +0200
@@ -0,0 +1,74 @@
+/*
+ * drivers/s390/char/sclp_config.c
+ *
+ * Copyright IBM Corp. 2007
+ * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
+ */
+
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/cpu.h>
+#include <linux/sysdev.h>
+#include <linux/workqueue.h>
+#include "sclp.h"
+
+#define TAG "sclp_config: "
+
+struct conf_mgm_data {
+ u8 reserved;
+ u8 ev_qualifier;
+} __attribute__((packed));
+
+#define EV_QUAL_CAP_CHANGE 3
+
+static struct work_struct sclp_cpu_capability_work;
+
+static void sclp_cpu_capability_notify(struct work_struct *work)
+{
+ int cpu;
+ struct sys_device *sysdev;
+
+ lock_cpu_hotplug();
+ for_each_online_cpu(cpu) {
+ sysdev = get_cpu_sysdev(cpu);
+ kobject_uevent(&sysdev->kobj, KOBJ_CHANGE);
+ }
+ unlock_cpu_hotplug();
+}
+
+static void sclp_conf_receiver_fn(struct evbuf_header *evbuf)
+{
+ struct conf_mgm_data *cdata;
+
+ cdata = (struct conf_mgm_data *)(evbuf + 1);
+ if (cdata->ev_qualifier == EV_QUAL_CAP_CHANGE)
+ schedule_work(&sclp_cpu_capability_work);
+}
+
+static struct sclp_register sclp_conf_register =
+{
+ .receive_mask = EVTYP_CONFMGMDATA_MASK,
+ .receiver_fn = sclp_conf_receiver_fn,
+};
+
+static int __init sclp_conf_init(void)
+{
+ int rc;
+
+ INIT_WORK(&sclp_cpu_capability_work, sclp_cpu_capability_notify);
+
+ rc = sclp_register(&sclp_conf_register);
+ if (rc) {
+ printk(KERN_ERR TAG "failed to register (%d).\n", rc);
+ return rc;
+ }
+
+ if (!(sclp_conf_register.sclp_receive_mask & EVTYP_CONFMGMDATA_MASK)) {
+ printk(KERN_WARNING TAG "no configuration management.\n");
+ sclp_unregister(&sclp_conf_register);
+ rc = -ENOSYS;
+ }
+ return rc;
+}
+
+__initcall(sclp_conf_init);
diff -urpN linux-2.6/drivers/s390/char/sclp.h linux-2.6-patched/drivers/s390/char/sclp.h
--- linux-2.6/drivers/s390/char/sclp.h 2007-04-02 18:11:17.000000000 +0200
+++ linux-2.6-patched/drivers/s390/char/sclp.h 2007-04-02 18:11:20.000000000 +0200
@@ -27,6 +27,7 @@
#define EVTYP_CNTLPROGIDENT 0x0B
#define EVTYP_SIGQUIESCE 0x1D
#define EVTYP_VT220MSG 0x1A
+#define EVTYP_CONFMGMDATA 0x04
#define EVTYP_SDIAS 0x1C

#define EVTYP_OPCMD_MASK 0x80000000
@@ -37,6 +38,7 @@
#define EVTYP_CTLPROGIDENT_MASK 0x00200000
#define EVTYP_SIGQUIESCE_MASK 0x00000008
#define EVTYP_VT220MSG_MASK 0x00000040
+#define EVTYP_CONFMGMDATA_MASK 0x10000000
#define EVTYP_SDIAS_MASK 0x00000010

#define GNRLMSGFLGS_DOM 0x8000
diff -urpN linux-2.6/drivers/s390/sysinfo.c linux-2.6-patched/drivers/s390/sysinfo.c
--- linux-2.6/drivers/s390/sysinfo.c 2007-04-02 18:10:40.000000000 +0200
+++ linux-2.6-patched/drivers/s390/sysinfo.c 2007-04-02 18:11:20.000000000 +0200
@@ -357,6 +357,24 @@ static __init int create_proc_sysinfo(vo

__initcall(create_proc_sysinfo);

+int get_cpu_capability(unsigned int *capability)
+{
+ struct sysinfo_1_2_2 *info;
+ int rc;
+
+ info = (void *) get_zeroed_page(GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+ rc = stsi(info, 1, 2, 2);
+ if (rc == -ENOSYS)
+ goto out;
+ rc = 0;
+ *capability = info->capability;
+out:
+ free_page((unsigned long) info);
+ return rc;
+}
+
/*
* CPU capability might have changed. Therefore recalculate loops_per_jiffy.
*/
diff -urpN linux-2.6/include/asm-s390/processor.h linux-2.6-patched/include/asm-s390/processor.h
--- linux-2.6/include/asm-s390/processor.h 2007-04-02 18:10:54.000000000 +0200
+++ linux-2.6-patched/include/asm-s390/processor.h 2007-04-02 18:11:20.000000000 +0200
@@ -57,6 +57,7 @@ struct cpuinfo_S390

extern void s390_adjust_jiffies(void);
extern void print_cpu_info(struct cpuinfo_S390 *);
+extern int get_cpu_capability(unsigned int *);

/* Lazy FPU handling on uni-processor */
extern struct task_struct *last_task_used_math;
-
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