Mailing List Archive

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1271674079 -3600
# Node ID f1313dd68da4077ccd4f5530a7bc79d649bdffab
# Parent 652e40d4dd8864a16084a1ff634d95f4a7260f20
stopmachine: Implement using tasklets rather than a softirq.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
---
xen/arch/ia64/xen/domain.c | 4 ++++
xen/arch/x86/domain.c | 5 +++++
xen/common/stop_machine.c | 19 +++++++++++--------
xen/include/xen/sched.h | 3 +++
xen/include/xen/softirq.h | 1 -
5 files changed, 23 insertions(+), 9 deletions(-)

diff -r 652e40d4dd88 -r f1313dd68da4 xen/arch/ia64/xen/domain.c
--- a/xen/arch/ia64/xen/domain.c Mon Apr 19 11:34:49 2010 +0100
+++ b/xen/arch/ia64/xen/domain.c Mon Apr 19 11:47:59 2010 +0100
@@ -2343,6 +2343,10 @@ void machine_halt(void)
while(1);
}

+void sync_local_execstate(void)
+{
+}
+
void sync_vcpu_execstate(struct vcpu *v)
{
// __ia64_save_fpu(v->arch._thread.fph);
diff -r 652e40d4dd88 -r f1313dd68da4 xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c Mon Apr 19 11:34:49 2010 +0100
+++ b/xen/arch/x86/domain.c Mon Apr 19 11:47:59 2010 +0100
@@ -1509,6 +1509,11 @@ int __sync_lazy_execstate(void)
return switch_required;
}

+void sync_local_execstate(void)
+{
+ (void)__sync_lazy_execstate();
+}
+
void sync_vcpu_execstate(struct vcpu *v)
{
if ( cpu_isset(smp_processor_id(), v->vcpu_dirty_cpumask) )
diff -r 652e40d4dd88 -r f1313dd68da4 xen/common/stop_machine.c
--- a/xen/common/stop_machine.c Mon Apr 19 11:34:49 2010 +0100
+++ b/xen/common/stop_machine.c Mon Apr 19 11:47:59 2010 +0100
@@ -24,7 +24,7 @@
#include <xen/init.h>
#include <xen/sched.h>
#include <xen/spinlock.h>
-#include <xen/softirq.h>
+#include <xen/tasklet.h>
#include <xen/stop_machine.h>
#include <xen/errno.h>
#include <xen/smp.h>
@@ -51,6 +51,7 @@ struct stopmachine_data {
void *fn_data;
};

+static DEFINE_PER_CPU(struct tasklet, stopmachine_tasklet);
static struct stopmachine_data stopmachine_data;
static DEFINE_SPINLOCK(stopmachine_lock);

@@ -81,10 +82,7 @@ int stop_machine_run(int (*fn)(void *),
return (*fn)(data);
}

- /* Note: We shouldn't spin on lock when it's held by others since others
- * is expecting this cpus to enter softirq context. Or else deadlock
- * is caused.
- */
+ /* Must not spin here as the holder will expect us to be descheduled. */
if ( !spin_trylock(&stopmachine_lock) )
return -EBUSY;

@@ -98,8 +96,9 @@ int stop_machine_run(int (*fn)(void *),
smp_wmb();

for_each_cpu_mask ( i, allbutself )
- cpu_raise_softirq(i, STOPMACHINE_SOFTIRQ);
+ tasklet_schedule_on_cpu(&per_cpu(stopmachine_tasklet, i), i);

+ sync_local_execstate();
stopmachine_set_state(STOPMACHINE_PREPARE);

local_irq_disable();
@@ -118,10 +117,11 @@ int stop_machine_run(int (*fn)(void *),
return ret;
}

-static void stopmachine_softirq(void)
+static void stopmachine_action(unsigned long unused)
{
enum stopmachine_state state = STOPMACHINE_START;

+ sync_local_execstate();
smp_mb();

while ( state != STOPMACHINE_EXIT )
@@ -153,7 +153,10 @@ static void stopmachine_softirq(void)

static int __init cpu_stopmachine_init(void)
{
- open_softirq(STOPMACHINE_SOFTIRQ, stopmachine_softirq);
+ unsigned int cpu;
+ for_each_possible_cpu ( cpu )
+ tasklet_init(&per_cpu(stopmachine_tasklet, cpu),
+ stopmachine_action, 0);
return 0;
}
__initcall(cpu_stopmachine_init);
diff -r 652e40d4dd88 -r f1313dd68da4 xen/include/xen/sched.h
--- a/xen/include/xen/sched.h Mon Apr 19 11:34:49 2010 +0100
+++ b/xen/include/xen/sched.h Mon Apr 19 11:47:59 2010 +0100
@@ -480,6 +480,9 @@ void vcpu_sleep_sync(struct vcpu *d);
*/
void sync_vcpu_execstate(struct vcpu *v);

+/* As above, for any lazy state being held on the local CPU. */
+void sync_local_execstate(void);
+
/*
* Called by the scheduler to switch to another VCPU. This function must
* call context_saved(@prev) when the local CPU is no longer running in
diff -r 652e40d4dd88 -r f1313dd68da4 xen/include/xen/softirq.h
--- a/xen/include/xen/softirq.h Mon Apr 19 11:34:49 2010 +0100
+++ b/xen/include/xen/softirq.h Mon Apr 19 11:47:59 2010 +0100
@@ -8,7 +8,6 @@ enum {
NEW_TLBFLUSH_CLOCK_PERIOD_SOFTIRQ,
PAGE_SCRUB_SOFTIRQ,
RCU_SOFTIRQ,
- STOPMACHINE_SOFTIRQ,
NR_COMMON_SOFTIRQS
};


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