# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1172685319 0
# Node ID c3c03089c59ef515766636dd4afef6573f3b6b42
# Parent 8ba425b640b3c7f81c17eb45972eff6eabe9f94d
linux: More save/restore fixes. Fix deadlock of cpu_hotplug_lock vs
workqueue_mutex. This is a new deadlock since the workqueue_mutex is
acquired in the workqueue_cpu_calbback() function across
CPU_UP_PREPARE->CPU_ONLINE.
The fix is for us not to rudely grab the cpu_hotplug_lock() during
save/restore -- it's really not necessary.
This patch is applicable to any of our 2.6 kernels, but is absolutely
required from 2.6.18 onwards.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
linux-2.6-xen-sparse/drivers/xen/core/cpu_hotplug.c | 37 +++++------------
linux-2.6-xen-sparse/drivers/xen/core/machine_reboot.c | 24 +++++++----
linux-2.6-xen-sparse/drivers/xen/core/smpboot.c | 11 +----
linux-2.6-xen-sparse/include/xen/cpu_hotplug.h | 6 --
4 files changed, 32 insertions(+), 46 deletions(-)
diff -r 8ba425b640b3 -r c3c03089c59e
linux-2.6-xen-sparse/drivers/xen/core/cpu_hotplug.c
--- a/linux-2.6-xen-sparse/drivers/xen/core/cpu_hotplug.c Wed Feb 28
11:13:49 2007 -0500
+++ b/linux-2.6-xen-sparse/drivers/xen/core/cpu_hotplug.c Wed Feb 28
17:55:19 2007 +0000
@@ -121,29 +121,19 @@ arch_initcall(setup_vcpu_hotplug_event);
int smp_suspend(void)
{
- int i, err;
+ int cpu, err;
- lock_cpu_hotplug();
-
- /*
- * Take all other CPUs offline. We hold the hotplug mutex to
- * avoid other processes bringing up CPUs under our feet.
- */
- while (num_online_cpus() > 1) {
- unlock_cpu_hotplug();
- for_each_online_cpu(i) {
- if (i == 0)
- continue;
- err = cpu_down(i);
- if (err) {
- printk(KERN_CRIT "Failed to take all CPUs "
- "down: %d.\n", err);
- for_each_possible_cpu(i)
- vcpu_hotplug(i);
- return err;
- }
+ for_each_online_cpu(cpu) {
+ if (cpu == 0)
+ continue;
+ err = cpu_down(cpu);
+ if (err) {
+ printk(KERN_CRIT "Failed to take all CPUs "
+ "down: %d.\n", err);
+ for_each_possible_cpu(cpu)
+ vcpu_hotplug(cpu);
+ return err;
}
- lock_cpu_hotplug();
}
return 0;
@@ -152,11 +142,6 @@ void smp_resume(void)
void smp_resume(void)
{
int cpu;
-
- for_each_possible_cpu(cpu)
- cpu_initialize_context(cpu);
-
- unlock_cpu_hotplug();
for_each_possible_cpu(cpu)
vcpu_hotplug(cpu);
diff -r 8ba425b640b3 -r c3c03089c59e
linux-2.6-xen-sparse/drivers/xen/core/machine_reboot.c
--- a/linux-2.6-xen-sparse/drivers/xen/core/machine_reboot.c Wed Feb 28
11:13:49 2007 -0500
+++ b/linux-2.6-xen-sparse/drivers/xen/core/machine_reboot.c Wed Feb 28
17:55:19 2007 +0000
@@ -97,6 +97,9 @@ static void post_suspend(int suspend_can
pfn_to_mfn(xen_start_info->store_mfn);
xen_start_info->console.domU.mfn =
pfn_to_mfn(xen_start_info->console.domU.mfn);
+ } else {
+ extern cpumask_t cpu_initialized_map;
+ cpu_initialized_map = cpumask_of_cpu(0);
}
set_fixmap(FIX_SHARED_INFO, xen_start_info->shared_info);
@@ -147,13 +150,20 @@ int __xen_suspend(void)
}
#endif
- err = smp_suspend();
- if (err)
- return err;
-
- xenbus_suspend();
-
- preempt_disable();
+ for (;;) {
+ err = smp_suspend();
+ if (err)
+ return err;
+
+ xenbus_suspend();
+ preempt_disable();
+
+ if (num_online_cpus() == 1)
+ break;
+
+ preempt_enable();
+ xenbus_suspend_cancel();
+ }
mm_pin_all();
local_irq_disable();
diff -r 8ba425b640b3 -r c3c03089c59e
linux-2.6-xen-sparse/drivers/xen/core/smpboot.c
--- a/linux-2.6-xen-sparse/drivers/xen/core/smpboot.c Wed Feb 28 11:13:49
2007 -0500
+++ b/linux-2.6-xen-sparse/drivers/xen/core/smpboot.c Wed Feb 28 17:55:19
2007 +0000
@@ -47,7 +47,7 @@ EXPORT_SYMBOL(cpu_online_map);
EXPORT_SYMBOL(cpu_online_map);
cpumask_t cpu_possible_map;
EXPORT_SYMBOL(cpu_possible_map);
-static cpumask_t cpu_initialized_map;
+cpumask_t cpu_initialized_map;
struct cpuinfo_x86 cpu_data[NR_CPUS] __cacheline_aligned;
EXPORT_SYMBOL(cpu_data);
@@ -185,7 +185,7 @@ static void cpu_bringup_and_idle(void)
cpu_idle();
}
-void cpu_initialize_context(unsigned int cpu)
+static void cpu_initialize_context(unsigned int cpu)
{
vcpu_guest_context_t ctxt;
struct task_struct *idle = idle_task(cpu);
@@ -195,7 +195,7 @@ void cpu_initialize_context(unsigned int
struct Xgt_desc_struct *gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
#endif
- if (cpu == 0)
+ if (cpu_test_and_set(cpu, cpu_initialized_map))
return;
memset(&ctxt, 0, sizeof(ctxt));
@@ -417,10 +417,7 @@ int __devinit __cpu_up(unsigned int cpu)
if (rc)
return rc;
- if (!cpu_isset(cpu, cpu_initialized_map)) {
- cpu_set(cpu, cpu_initialized_map);
- cpu_initialize_context(cpu);
- }
+ cpu_initialize_context(cpu);
if (num_online_cpus() == 1)
alternatives_smp_switch(1);
diff -r 8ba425b640b3 -r c3c03089c59e
linux-2.6-xen-sparse/include/xen/cpu_hotplug.h
--- a/linux-2.6-xen-sparse/include/xen/cpu_hotplug.h Wed Feb 28 11:13:49
2007 -0500
+++ b/linux-2.6-xen-sparse/include/xen/cpu_hotplug.h Wed Feb 28 17:55:19
2007 +0000
@@ -5,12 +5,6 @@
#include <linux/cpumask.h>
#if defined(CONFIG_HOTPLUG_CPU)
-
-#if defined(CONFIG_X86)
-void cpu_initialize_context(unsigned int cpu);
-#else
-#define cpu_initialize_context(cpu) ((void)0)
-#endif
int cpu_up_check(unsigned int cpu);
void init_xenbus_allowed_cpumask(void);
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