[PATCH 1/2] tracing/filter: remove preds from struct event_subsystem

[PATCH 1/2] tracing/filter: remove preds from struct event_subsystem

[Xiao Guangrong]

No need to save preds to event_subsystem, because it's not used.

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
 kernel/trace/trace_events_filter.c |   39 +++++------------------------------
 1 files changed, 6 insertions(+), 33 deletions(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 936c621..b9aae72 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -420,17 +420,7 @@ EXPORT_SYMBOL_GPL(init_preds);
 
 static void filter_free_subsystem_preds(struct event_subsystem *system)
 {
-	struct event_filter *filter = system->filter;
 	struct ftrace_event_call *call;
-	int i;
-
-	if (filter->n_preds) {
-		for (i = 0; i < filter->n_preds; i++)
-			filter_free_pred(filter->preds[i]);
-		kfree(filter->preds);
-		filter->preds = NULL;
-		filter->n_preds = 0;
-	}
 
 	list_for_each_entry(call, &ftrace_events, list) {
 		if (!call->define_fields)
@@ -607,26 +597,9 @@ static int filter_add_subsystem_pred(struct filter_parse_state *ps,
 				     struct filter_pred *pred,
 				     char *filter_string)
 {
-	struct event_filter *filter = system->filter;
 	struct ftrace_event_call *call;
 	int err = 0;
 
-	if (!filter->preds) {
-		filter->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
-					GFP_KERNEL);
-
-		if (!filter->preds)
-			return -ENOMEM;
-	}
-
-	if (filter->n_preds == MAX_FILTER_PRED) {
-		parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
-		return -ENOSPC;
-	}
-
-	filter->preds[filter->n_preds] = pred;
-	filter->n_preds++;
-
 	list_for_each_entry(call, &ftrace_events, list) {
 
 		if (!call->define_fields)
@@ -1029,12 +1002,12 @@ static int replace_preds(struct event_subsystem *system,
 
 		if (elt->op == OP_AND || elt->op == OP_OR) {
 			pred = create_logical_pred(elt->op);
-			if (call) {
+			if (call)
 				err = filter_add_pred(ps, call, pred);
-				filter_free_pred(pred);
-			} else
+			else
 				err = filter_add_subsystem_pred(ps, system,
 							pred, filter_string);
+			filter_free_pred(pred);
 			if (err)
 				return err;
 
@@ -1048,12 +1021,12 @@ static int replace_preds(struct event_subsystem *system,
 		}
 
 		pred = create_pred(elt->op, operand1, operand2);
-		if (call) {
+		if (call)
 			err = filter_add_pred(ps, call, pred);
-			filter_free_pred(pred);
-		} else
+		else
 			err = filter_add_subsystem_pred(ps, system, pred,
 							filter_string);
+		filter_free_pred(pred);
 		if (err)
 			return err;
 
-- 
1.6.1.2

[PATCH 2/2] tracing/filter: remove empty subsystem and it's directory

[Xiao Guangrong]

Remove empty subsystem and it's directory when module unload.

Before patch:
 # rmmod trace-events-sample.ko
 # ls sample
 enable  filter

After patch:
 # rmmod trace-events-sample.ko
 # ls sample
 ls: cannot access sample: No such file or directory

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
 kernel/trace/trace.h        |    1 +
 kernel/trace/trace_events.c |   32 +++++++++++++++++++++++++++++++-
 2 files changed, 32 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 61b4e94..0e7de4b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -780,6 +780,7 @@ struct event_subsystem {
 	const char		*name;
 	struct dentry		*entry;
 	void			*filter;
+	int			nr_events;
 };
 
 struct filter_pred;
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index fecac13..90cf936 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -851,8 +851,10 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
 
 	/* First see if we did not already create this dir */
 	list_for_each_entry(system, &event_subsystems, list) {
-		if (strcmp(system->name, name) == 0)
+		if (strcmp(system->name, name) == 0) {
+			system->nr_events++;
 			return system->entry;
+		}
 	}
 
 	/* need to create new entry */
@@ -871,6 +873,7 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
 		return d_events;
 	}
 
+	system->nr_events = 1;
 	system->name = kstrdup(name, GFP_KERNEL);
 	if (!system->name) {
 		debugfs_remove(system->entry);
@@ -905,6 +908,32 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
 	return system->entry;
 }
 
+static void remove_subsystem_dir(const char *name)
+{
+	struct event_subsystem *system;
+
+	if (strcmp(name, TRACE_SYSTEM) == 0)
+		return;
+
+	list_for_each_entry(system, &event_subsystems, list) {
+		if (strcmp(system->name, name) == 0) {
+			if (!--system->nr_events) {
+				struct event_filter *filter = system->filter;
+
+				debugfs_remove_recursive(system->entry);
+				list_del(&system->list);
+				if (filter) {
+					kfree(filter->filter_string);
+					kfree(filter);
+				}
+				kfree(system->name);
+				kfree(system);
+			}
+			break;
+		}
+	}
+}
+
 static int
 event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
 		 const struct file_operations *id,
@@ -1079,6 +1108,7 @@ static void trace_module_remove_events(struct module *mod)
 			list_del(&call->list);
 			trace_destroy_fields(call);
 			destroy_preds(call);
+			remove_subsystem_dir(call->system);
 		}
 	}
 
-- 
1.6.1.2

Re: [PATCH 1/2] tracing/filter: remove preds from struct event_subsystem

[Tom Zanussi]

On Thu, 2009-07-09 at 16:20 +0800, Xiao Guangrong wrote:
> No need to save preds to event_subsystem, because it's not used.
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>

Makes sense to me.

Acked-by: Tom Zanussi <tzanussi@gmail.com>

> ---
>  kernel/trace/trace_events_filter.c |   39 +++++------------------------------
>  1 files changed, 6 insertions(+), 33 deletions(-)
> 
> diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
> index 936c621..b9aae72 100644
> --- a/kernel/trace/trace_events_filter.c
> +++ b/kernel/trace/trace_events_filter.c
> @@ -420,17 +420,7 @@ EXPORT_SYMBOL_GPL(init_preds);
>  
>  static void filter_free_subsystem_preds(struct event_subsystem *system)
>  {
> -	struct event_filter *filter = system->filter;
>  	struct ftrace_event_call *call;
> -	int i;
> -
> -	if (filter->n_preds) {
> -		for (i = 0; i < filter->n_preds; i++)
> -			filter_free_pred(filter->preds[i]);
> -		kfree(filter->preds);
> -		filter->preds = NULL;
> -		filter->n_preds = 0;
> -	}
>  
>  	list_for_each_entry(call, &ftrace_events, list) {
>  		if (!call->define_fields)
> @@ -607,26 +597,9 @@ static int filter_add_subsystem_pred(struct filter_parse_state *ps,
>  				     struct filter_pred *pred,
>  				     char *filter_string)
>  {
> -	struct event_filter *filter = system->filter;
>  	struct ftrace_event_call *call;
>  	int err = 0;
>  
> -	if (!filter->preds) {
> -		filter->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
> -					GFP_KERNEL);
> -
> -		if (!filter->preds)
> -			return -ENOMEM;
> -	}
> -
> -	if (filter->n_preds == MAX_FILTER_PRED) {
> -		parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
> -		return -ENOSPC;
> -	}
> -
> -	filter->preds[filter->n_preds] = pred;
> -	filter->n_preds++;
> -
>  	list_for_each_entry(call, &ftrace_events, list) {
>  
>  		if (!call->define_fields)
> @@ -1029,12 +1002,12 @@ static int replace_preds(struct event_subsystem *system,
>  
>  		if (elt->op == OP_AND || elt->op == OP_OR) {
>  			pred = create_logical_pred(elt->op);
> -			if (call) {
> +			if (call)
>  				err = filter_add_pred(ps, call, pred);
> -				filter_free_pred(pred);
> -			} else
> +			else
>  				err = filter_add_subsystem_pred(ps, system,
>  							pred, filter_string);
> +			filter_free_pred(pred);
>  			if (err)
>  				return err;
>  
> @@ -1048,12 +1021,12 @@ static int replace_preds(struct event_subsystem *system,
>  		}
>  
>  		pred = create_pred(elt->op, operand1, operand2);
> -		if (call) {
> +		if (call)
>  			err = filter_add_pred(ps, call, pred);
> -			filter_free_pred(pred);
> -		} else
> +		else
>  			err = filter_add_subsystem_pred(ps, system, pred,
>  							filter_string);
> +		filter_free_pred(pred);
>  		if (err)
>  			return err;
>  

Re: [PATCH 2/2] tracing/filter: remove empty subsystem and it's directory

[Tom Zanussi]

On Thu, 2009-07-09 at 16:22 +0800, Xiao Guangrong wrote:
> Remove empty subsystem and it's directory when module unload.
> 
> Before patch:
>  # rmmod trace-events-sample.ko
>  # ls sample
>  enable  filter
> 
> After patch:
>  # rmmod trace-events-sample.ko
>  # ls sample
>  ls: cannot access sample: No such file or directory
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>

Looks like it does the trick.

Acked-by: Tom Zanussi <tzanussi@gmail.com>

> ---
>  kernel/trace/trace.h        |    1 +
>  kernel/trace/trace_events.c |   32 +++++++++++++++++++++++++++++++-
>  2 files changed, 32 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 61b4e94..0e7de4b 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -780,6 +780,7 @@ struct event_subsystem {
>  	const char		*name;
>  	struct dentry		*entry;
>  	void			*filter;
> +	int			nr_events;
>  };
>  
>  struct filter_pred;
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index fecac13..90cf936 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -851,8 +851,10 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
>  
>  	/* First see if we did not already create this dir */
>  	list_for_each_entry(system, &event_subsystems, list) {
> -		if (strcmp(system->name, name) == 0)
> +		if (strcmp(system->name, name) == 0) {
> +			system->nr_events++;
>  			return system->entry;
> +		}
>  	}
>  
>  	/* need to create new entry */
> @@ -871,6 +873,7 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
>  		return d_events;
>  	}
>  
> +	system->nr_events = 1;
>  	system->name = kstrdup(name, GFP_KERNEL);
>  	if (!system->name) {
>  		debugfs_remove(system->entry);
> @@ -905,6 +908,32 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
>  	return system->entry;
>  }
>  
> +static void remove_subsystem_dir(const char *name)
> +{
> +	struct event_subsystem *system;
> +
> +	if (strcmp(name, TRACE_SYSTEM) == 0)
> +		return;
> +
> +	list_for_each_entry(system, &event_subsystems, list) {
> +		if (strcmp(system->name, name) == 0) {
> +			if (!--system->nr_events) {
> +				struct event_filter *filter = system->filter;
> +
> +				debugfs_remove_recursive(system->entry);
> +				list_del(&system->list);
> +				if (filter) {
> +					kfree(filter->filter_string);
> +					kfree(filter);
> +				}
> +				kfree(system->name);
> +				kfree(system);
> +			}
> +			break;
> +		}
> +	}
> +}
> +
>  static int
>  event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
>  		 const struct file_operations *id,
> @@ -1079,6 +1108,7 @@ static void trace_module_remove_events(struct module *mod)
>  			list_del(&call->list);
>  			trace_destroy_fields(call);
>  			destroy_preds(call);
> +			remove_subsystem_dir(call->system);
>  		}
>  	}
>  

Re: [PATCH 1/2] tracing/filter: remove preds from struct event_subsystem

[Li Zefan]

Xiao Guangrong wrote:
> No need to save preds to event_subsystem, because it's not used.
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>

Nice cleanup.

Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>

> ---
>  kernel/trace/trace_events_filter.c |   39 +++++------------------------------
>  1 files changed, 6 insertions(+), 33 deletions(-)

Re: [PATCH 2/2] tracing/filter: remove empty subsystem and it's directory

[Li Zefan]

Tom Zanussi wrote:
> On Thu, 2009-07-09 at 16:22 +0800, Xiao Guangrong wrote:
>> Remove empty subsystem and it's directory when module unload.
>>
>> Before patch:
>>  # rmmod trace-events-sample.ko
>>  # ls sample
>>  enable  filter
>>
>> After patch:
>>  # rmmod trace-events-sample.ko
>>  # ls sample
>>  ls: cannot access sample: No such file or directory
>>
>> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> 
> Looks like it does the trick.
> 
> Acked-by: Tom Zanussi <tzanussi@gmail.com>
> 

It sure does. :)

Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>

>> ---
>>  kernel/trace/trace.h        |    1 +
>>  kernel/trace/trace_events.c |   32 +++++++++++++++++++++++++++++++-
>>  2 files changed, 32 insertions(+), 1 deletions(-)

[tip:tracing/core] tracing/filter: Remove preds from struct event_subsystem

[tip-bot for Xiao Guangrong]

Commit-ID:  c5cb183608167c744cb28bbd85884be5a4ce875d
Gitweb:     http://git.kernel.org/tip/c5cb183608167c744cb28bbd85884be5a4ce875d
Author:     Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
AuthorDate: Thu, 9 Jul 2009 16:20:12 +0800
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 10 Jul 2009 11:55:27 +0200

tracing/filter: Remove preds from struct event_subsystem

No need to save preds to event_subsystem, because it's not used.

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: Tom Zanussi <tzanussi@gmail.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A55A83C.1030005@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 kernel/trace/trace_events_filter.c |   39 +++++------------------------------
 1 files changed, 6 insertions(+), 33 deletions(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 936c621..b9aae72 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -420,17 +420,7 @@ EXPORT_SYMBOL_GPL(init_preds);
 
 static void filter_free_subsystem_preds(struct event_subsystem *system)
 {
-	struct event_filter *filter = system->filter;
 	struct ftrace_event_call *call;
-	int i;
-
-	if (filter->n_preds) {
-		for (i = 0; i < filter->n_preds; i++)
-			filter_free_pred(filter->preds[i]);
-		kfree(filter->preds);
-		filter->preds = NULL;
-		filter->n_preds = 0;
-	}
 
 	list_for_each_entry(call, &ftrace_events, list) {
 		if (!call->define_fields)
@@ -607,26 +597,9 @@ static int filter_add_subsystem_pred(struct filter_parse_state *ps,
 				     struct filter_pred *pred,
 				     char *filter_string)
 {
-	struct event_filter *filter = system->filter;
 	struct ftrace_event_call *call;
 	int err = 0;
 
-	if (!filter->preds) {
-		filter->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
-					GFP_KERNEL);
-
-		if (!filter->preds)
-			return -ENOMEM;
-	}
-
-	if (filter->n_preds == MAX_FILTER_PRED) {
-		parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
-		return -ENOSPC;
-	}
-
-	filter->preds[filter->n_preds] = pred;
-	filter->n_preds++;
-
 	list_for_each_entry(call, &ftrace_events, list) {
 
 		if (!call->define_fields)
@@ -1029,12 +1002,12 @@ static int replace_preds(struct event_subsystem *system,
 
 		if (elt->op == OP_AND || elt->op == OP_OR) {
 			pred = create_logical_pred(elt->op);
-			if (call) {
+			if (call)
 				err = filter_add_pred(ps, call, pred);
-				filter_free_pred(pred);
-			} else
+			else
 				err = filter_add_subsystem_pred(ps, system,
 							pred, filter_string);
+			filter_free_pred(pred);
 			if (err)
 				return err;
 
@@ -1048,12 +1021,12 @@ static int replace_preds(struct event_subsystem *system,
 		}
 
 		pred = create_pred(elt->op, operand1, operand2);
-		if (call) {
+		if (call)
 			err = filter_add_pred(ps, call, pred);
-			filter_free_pred(pred);
-		} else
+		else
 			err = filter_add_subsystem_pred(ps, system, pred,
 							filter_string);
+		filter_free_pred(pred);
 		if (err)
 			return err;
 

[tip:tracing/core] tracing/filter: Remove empty subsystem and its directory

[tip-bot for Xiao Guangrong]

Commit-ID:  dc82ec98a4727fd51b77e92d05fe7d2db3dcc11c
Gitweb:     http://git.kernel.org/tip/dc82ec98a4727fd51b77e92d05fe7d2db3dcc11c
Author:     Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
AuthorDate: Thu, 9 Jul 2009 16:22:22 +0800
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 10 Jul 2009 11:55:28 +0200

tracing/filter: Remove empty subsystem and its directory

Remove empty subsystem and its directory when module unload.

Before patch:
 # rmmod trace-events-sample.ko
 # ls sample
 enable  filter

After patch:
 # rmmod trace-events-sample.ko
 # ls sample
 ls: cannot access sample: No such file or directory

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: Tom Zanussi <tzanussi@gmail.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A55A8BE.9010707@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 kernel/trace/trace.h        |    1 +
 kernel/trace/trace_events.c |   32 +++++++++++++++++++++++++++++++-
 2 files changed, 32 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 52eb0d8..94305c7 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -757,6 +757,7 @@ struct event_subsystem {
 	const char		*name;
 	struct dentry		*entry;
 	void			*filter;
+	int			nr_events;
 };
 
 struct filter_pred;
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index fecac13..90cf936 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -851,8 +851,10 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
 
 	/* First see if we did not already create this dir */
 	list_for_each_entry(system, &event_subsystems, list) {
-		if (strcmp(system->name, name) == 0)
+		if (strcmp(system->name, name) == 0) {
+			system->nr_events++;
 			return system->entry;
+		}
 	}
 
 	/* need to create new entry */
@@ -871,6 +873,7 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
 		return d_events;
 	}
 
+	system->nr_events = 1;
 	system->name = kstrdup(name, GFP_KERNEL);
 	if (!system->name) {
 		debugfs_remove(system->entry);
@@ -905,6 +908,32 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
 	return system->entry;
 }
 
+static void remove_subsystem_dir(const char *name)
+{
+	struct event_subsystem *system;
+
+	if (strcmp(name, TRACE_SYSTEM) == 0)
+		return;
+
+	list_for_each_entry(system, &event_subsystems, list) {
+		if (strcmp(system->name, name) == 0) {
+			if (!--system->nr_events) {
+				struct event_filter *filter = system->filter;
+
+				debugfs_remove_recursive(system->entry);
+				list_del(&system->list);
+				if (filter) {
+					kfree(filter->filter_string);
+					kfree(filter);
+				}
+				kfree(system->name);
+				kfree(system);
+			}
+			break;
+		}
+	}
+}
+
 static int
 event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
 		 const struct file_operations *id,
@@ -1079,6 +1108,7 @@ static void trace_module_remove_events(struct module *mod)
 			list_del(&call->list);
 			trace_destroy_fields(call);
 			destroy_preds(call);
+			remove_subsystem_dir(call->system);
 		}
 	}
 

Re: [tip:tracing/core] tracing/filter: Remove empty subsystem and its directory

[Steven Rostedt]

On Fri, 10 Jul 2009, tip-bot for Xiao Guangrong wrote:

> Commit-ID:  dc82ec98a4727fd51b77e92d05fe7d2db3dcc11c
> Gitweb:     http://git.kernel.org/tip/dc82ec98a4727fd51b77e92d05fe7d2db3dcc11c
> Author:     Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> AuthorDate: Thu, 9 Jul 2009 16:22:22 +0800
> Committer:  Ingo Molnar <mingo@elte.hu>
> CommitDate: Fri, 10 Jul 2009 11:55:28 +0200
> 
> tracing/filter: Remove empty subsystem and its directory
> 
> Remove empty subsystem and its directory when module unload.
> 
> Before patch:
>  # rmmod trace-events-sample.ko
>  # ls sample
>  enable  filter
> 
> After patch:
>  # rmmod trace-events-sample.ko
>  # ls sample
>  ls: cannot access sample: No such file or directory
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> Acked-by: Tom Zanussi <tzanussi@gmail.com>
> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> LKML-Reference: <4A55A8BE.9010707@cn.fujitsu.com>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>

Thanks Xiao!

I've just came back from vacation so I missed acking it. But it looks 
good, and Ingo pulled it in.

-- Steve