On Fri, Mar 17, 2006 at 07:43:22PM +0530, Srivatsa Vaddagiri wrote:
> On Fri, Mar 17, 2006 at 01:04:12AM -0800, Andrew Morton wrote:
> > OK.. I guess we should fix those architectures while we're thinking about it.
>
> Only x86 has this bug, so only x86 needs to be fixed. Neverthless
> Ashok's patch [1] should address all architectures that may implement
> smp_prepare_cpu() in future as well.
>
Hi Vatsa
Since smp_prepare_cpu was introduced only to work around warm-boot on i386 due to the
strange kickstart process of AP's. I have moved this al-together within __cpu_up()
i386 arch code, so its less confusing to other arch's that have done it right already.
Here is the updated patch, it removes smp_prepare_cpu() from being called from generic
core cpuhotplug code, and moved it to i386 side.
I did some basic up/down testing on a 2 way PIII box.
Shaohua, could you take a look at this code, and also check suspend/resume is not
affected?
Andrew, could we queue it to -mm for some exposure before inclusion.
thanks
--
Cheers,
Ashok Raj
- Open Source Technology Center
Check if cpu can be onlined before calling smp_prepare_cpu()
- Moved check for online cpu out of smp_prepare_cpu()
- Moved default declaration of smp_prepare_cpu() to kernel/cpu.c
- Removed lock_cpu_hotplug() from smp_prepare_cpu() to around it, since
its called from cpu_up() as well now.
- Removed clearing from cpu_present_map during cpu_offline as it breaks using cpu_up()
directly during a subsequent online operation.
Signed-off-by: Ashok Raj <[email protected]>
--------------------------------------------------------
arch/i386/kernel/smpboot.c | 21 +++++++++++++++++----
drivers/base/cpu.c | 9 +--------
include/linux/cpu.h | 1 -
kernel/power/smp.c | 4 +---
4 files changed, 19 insertions(+), 16 deletions(-)
Index: linux-2.6.16-rc6-mm1/arch/i386/kernel/smpboot.c
===================================================================
--- linux-2.6.16-rc6-mm1.orig/arch/i386/kernel/smpboot.c
+++ linux-2.6.16-rc6-mm1/arch/i386/kernel/smpboot.c
@@ -1002,7 +1002,6 @@ void cpu_exit_clear(void)
cpu_clear(cpu, cpu_callout_map);
cpu_clear(cpu, cpu_callin_map);
- cpu_clear(cpu, cpu_present_map);
cpu_clear(cpu, smp_commenced_mask);
unmap_cpu_to_logical_apicid(cpu);
@@ -1021,14 +1020,13 @@ static void __devinit do_warm_boot_cpu(v
complete(info->complete);
}
-int __devinit smp_prepare_cpu(int cpu)
+static int __devinit __smp_prepare_cpu(int cpu)
{
DECLARE_COMPLETION(done);
struct warm_boot_cpu_info info;
struct work_struct task;
int apicid, ret;
- lock_cpu_hotplug();
apicid = x86_cpu_to_apicid[cpu];
if (apicid == BAD_APICID) {
ret = -ENODEV;
@@ -1053,7 +1051,6 @@ int __devinit smp_prepare_cpu(int cpu)
zap_low_mappings();
ret = 0;
exit:
- unlock_cpu_hotplug();
return ret;
}
#endif
@@ -1379,6 +1376,22 @@ void __cpu_die(unsigned int cpu)
int __devinit __cpu_up(unsigned int cpu)
{
+ int ret=0;
+
+#ifdef CONFIG_HOTPLUG_CPU
+ /*
+ * We do warm boot only on cpus that had booted earlier
+ * Otherwise cold boot is all handled from smp_boot_cpus().
+ * cpu_callin_map is set during AP kickstart process. Its reset
+ * when a cpu is taken offline from cpu_exit_clear().
+ */
+ if (!cpu_isset(cpu, cpu_callin_map))
+ ret = __smp_prepare_cpu(cpu);
+
+ if (ret)
+ return -EIO;
+#endif
+
/* In case one didn't come up */
if (!cpu_isset(cpu, cpu_callin_map)) {
printk(KERN_DEBUG "skipping cpu%d, didn't come online\n", cpu);
Index: linux-2.6.16-rc6-mm1/drivers/base/cpu.c
===================================================================
--- linux-2.6.16-rc6-mm1.orig/drivers/base/cpu.c
+++ linux-2.6.16-rc6-mm1/drivers/base/cpu.c
@@ -19,11 +19,6 @@ EXPORT_SYMBOL(cpu_sysdev_class);
static struct sys_device *cpu_sys_devices[NR_CPUS];
#ifdef CONFIG_HOTPLUG_CPU
-int __attribute__((weak)) smp_prepare_cpu (int cpu)
-{
- return 0;
-}
-
static ssize_t show_online(struct sys_device *dev, char *buf)
{
struct cpu *cpu = container_of(dev, struct cpu, sysdev);
@@ -44,9 +39,7 @@ static ssize_t store_online(struct sys_d
kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
break;
case '1':
- ret = smp_prepare_cpu(cpu->sysdev.id);
- if (!ret)
- ret = cpu_up(cpu->sysdev.id);
+ ret = cpu_up(cpu->sysdev.id);
if (!ret)
kobject_uevent(&dev->kobj, KOBJ_ONLINE);
break;
Index: linux-2.6.16-rc6-mm1/include/linux/cpu.h
===================================================================
--- linux-2.6.16-rc6-mm1.orig/include/linux/cpu.h
+++ linux-2.6.16-rc6-mm1/include/linux/cpu.h
@@ -74,7 +74,6 @@ extern int lock_cpu_hotplug_interruptibl
register_cpu_notifier(&fn##_nb); \
}
int cpu_down(unsigned int cpu);
-extern int __attribute__((weak)) smp_prepare_cpu(int cpu);
#define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))
#else
#define lock_cpu_hotplug() do { } while (0)
Index: linux-2.6.16-rc6-mm1/kernel/power/smp.c
===================================================================
--- linux-2.6.16-rc6-mm1.orig/kernel/power/smp.c
+++ linux-2.6.16-rc6-mm1/kernel/power/smp.c
@@ -49,9 +49,7 @@ void enable_nonboot_cpus(void)
printk("Thawing cpus ...\n");
for_each_cpu_mask(cpu, frozen_cpus) {
- error = smp_prepare_cpu(cpu);
- if (!error)
- error = cpu_up(cpu);
+ error = cpu_up(cpu);
if (!error) {
printk("CPU%d is up\n", cpu);
continue;
-
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