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* [PATCH 1/2 v5] tracing/uprobes: Support ftrace_event_file base multibuffer
@ 2013-07-04  6:53 zhangwei(Jovi)
  2013-07-04  7:01 ` [PATCH 1/2 v5 typo updated] " zhangwei(Jovi)
  0 siblings, 1 reply; 5+ messages in thread
From: zhangwei(Jovi) @ 2013-07-04  6:53 UTC (permalink / raw)
  To: Steven Rostedt, Oleg Nesterov, Masami Hiramatsu
  Cc: Frederic Weisbecker, Srikar Dronamraju, Ingo Molnar, linux-kernel

Support multi-buffer on uprobe-based dynamic events by
using ftrace_event_file.

This patch is based kprobe-based dynamic events multibuffer
support work initially, commited by Masami(commit 41a7dd420c),
but revised as below:

Oleg changed the kprobe-based multibuffer design from
array-pointers of ftrace_event_file into simple list,
so this patch also change to the list design.

rcu_read_lock/unlock added into uprobe_trace_func/uretprobe_trace_func,
to synchronize with ftrace_event_file list add and delete.

Even though we allow multi-uprobes instances now,
but TP_FLAG_PROFILE/TP_FLAG_TRACE are still mutually exclusive
in probe_event_enable currently, this means we cannot allow
one user is using uprobe-tracer, and another user is using
perf-probe on same uprobe concurrently.
(Perhaps this will be fix in future, kprobe dont't have this
limitation now)

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---
 kernel/trace/trace_uprobe.c |  119 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 100 insertions(+), 19 deletions(-)

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 32494fb0..2fc9931 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -53,6 +53,7 @@ struct trace_uprobe {
 	struct list_head		list;
 	struct ftrace_event_class	class;
 	struct ftrace_event_call	call;
+	struct list_head		files;
 	struct trace_uprobe_filter	filter;
 	struct uprobe_consumer		consumer;
 	struct inode			*inode;
@@ -65,6 +66,11 @@ struct trace_uprobe {
 	struct probe_arg		args[];
 };

+struct event_file_link {
+	struct ftrace_event_file	*file;
+	struct list_head		list;
+};
+
 #define SIZEOF_TRACE_UPROBE(n)			\
 	(offsetof(struct trace_uprobe, args) +	\
 	(sizeof(struct probe_arg) * (n)))
@@ -124,6 +130,7 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
 		goto error;

 	INIT_LIST_HEAD(&tu->list);
+	INIT_LIST_HEAD(&tu->files);
 	tu->consumer.handler = uprobe_dispatcher;
 	if (is_ret)
 		tu->consumer.ret_handler = uretprobe_dispatcher;
@@ -511,7 +518,8 @@ static const struct file_operations uprobe_profile_ops = {
 };

 static void uprobe_trace_print(struct trace_uprobe *tu,
-				unsigned long func, struct pt_regs *regs)
+				unsigned long func, struct pt_regs *regs,
+				struct ftrace_event_file *ftrace_file)
 {
 	struct uprobe_trace_entry_head *entry;
 	struct ring_buffer_event *event;
@@ -520,9 +528,12 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
 	int size, i;
 	struct ftrace_event_call *call = &tu->call;

+	WARN_ON(call != ftrace_file->event_call);
+
 	size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
-	event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
-						  size + tu->size, 0, 0);
+	event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
+						call->event.type,
+						size + tu->size, 0, 0);
 	if (!event)
 		return;

@@ -546,15 +557,28 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
 /* uprobe handler */
 static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
 {
-	if (!is_ret_probe(tu))
-		uprobe_trace_print(tu, 0, regs);
+	struct event_file_link *link;
+
+	if (is_ret_probe(tu))
+		return 0;
+
+	rcu_read_lock();
+	list_for_each_entry(link, &tu->files, list)
+		uprobe_trace_print(tu, 0, regs, link->file);
+	rcu_read_unlock();
+
 	return 0;
 }

 static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
 				struct pt_regs *regs)
 {
-	uprobe_trace_print(tu, func, regs);
+	struct event_file_link *link;
+
+	rcu_read_lock();
+	list_for_each_entry(link, &tu->files, list)
+		uprobe_trace_print(tu, func, regs, link->file);
+	rcu_read_unlock();
 }

 /* Event entry printers */
@@ -605,33 +629,89 @@ typedef bool (*filter_func_t)(struct uprobe_consumer *self,
 				struct mm_struct *mm);

 static int
-probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
+probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file,
+		   filter_func_t filter)
 {
-	int ret = 0;
+	bool enabled = is_trace_uprobe_enabled(tu);
+	struct event_file_link *link;
+	int ret;
+
+	if (file) {
+		if (tu->flags & TP_FLAG_PROFILE)
+			return -EINTR;

-	if (is_trace_uprobe_enabled(tu))
-		return -EINTR;
+		link = kmalloc(sizeof(*link), GFP_KERNEL);
+		if (!link)
+			return -ENOMEM;
+
+		link->file = file;
+		list_add_tail_rcu(&link->list, &tu->files);
+
+		tu->flags |= TP_FLAG_TRACE;
+	} else {
+		if (tu->flags & TP_FLAG_TRACE)
+			return -EINTR;
+
+		tu->flags |= TP_FLAG_PROFILE;
+	}

 	WARN_ON(!uprobe_filter_is_empty(&tu->filter));

-	tu->flags |= flag;
+	if (enabled)
+		return;
+
 	tu->consumer.filter = filter;
 	ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
-	if (ret)
-		tu->flags &= ~flag;
+	if (ret) {
+		if (file) {
+			list_del(&link->list);
+			kfree(link);
+			tu->flags &= ~TP_FLAG_TRACE;
+		} else
+			tu->flags &= ~TP_FLAG_PROFILE;
+	}

 	return ret;
 }

-static void probe_event_disable(struct trace_uprobe *tu, int flag)
+static struct event_file_link *
+find_event_file_link(struct trace_uprobe *tu, struct ftrace_event_file *file)
+{
+	struct event_file_link *link;
+
+	list_for_each_entry(link, &tu->files, list)
+		if (link->file == file)
+			return link;
+
+	return NULL;
+}
+
+static void
+probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file)
 {
 	if (!is_trace_uprobe_enabled(tu))
 		return;

+	if (file) {
+		struct event_file_link *link;
+
+		link = find_event_file_link(tu, file);
+		if (!link)
+			return;
+
+		list_del_rcu(&link->list);
+		/* synchronize with uprobe_trace_func/uretprobe_trace_func */
+		synchronize_sched();
+		kfree(link);
+
+		if (!list_empty(&tu->files))
+			return;
+	}
+
 	WARN_ON(!uprobe_filter_is_empty(&tu->filter));

 	uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
-	tu->flags &= ~flag;
+	tu->flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
 }

 static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
@@ -867,21 +947,22 @@ static
 int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
 {
 	struct trace_uprobe *tu = event->data;
+	struct ftrace_event_file *file = data;

 	switch (type) {
 	case TRACE_REG_REGISTER:
-		return probe_event_enable(tu, TP_FLAG_TRACE, NULL);
+		return probe_event_enable(tu, file, NULL);

 	case TRACE_REG_UNREGISTER:
-		probe_event_disable(tu, TP_FLAG_TRACE);
+		probe_event_disable(tu, file);
 		return 0;

 #ifdef CONFIG_PERF_EVENTS
 	case TRACE_REG_PERF_REGISTER:
-		return probe_event_enable(tu, TP_FLAG_PROFILE, uprobe_perf_filter);
+		return probe_event_enable(tu, NULL, uprobe_perf_filter);

 	case TRACE_REG_PERF_UNREGISTER:
-		probe_event_disable(tu, TP_FLAG_PROFILE);
+		probe_event_disable(tu, NULL);
 		return 0;

 	case TRACE_REG_PERF_OPEN:
-- 
1.7.9.7



^ permalink raw reply related	[flat|nested] 5+ messages in thread
* [PATCH 1/2 v5 typo updated] tracing/uprobes: Support ftrace_event_file base multibuffer
  2013-07-04  6:53 [PATCH 1/2 v5] tracing/uprobes: Support ftrace_event_file base multibuffer zhangwei(Jovi)
@ 2013-07-04  7:01 ` zhangwei(Jovi)
  2013-07-04  7:41   ` Namhyung Kim
  0 siblings, 1 reply; 5+ messages in thread
From: zhangwei(Jovi) @ 2013-07-04  7:01 UTC (permalink / raw)
  To: Steven Rostedt, Oleg Nesterov, Masami Hiramatsu
  Cc: Frederic Weisbecker, Srikar Dronamraju, Ingo Molnar, linux-kernel

Support multi-buffer on uprobe-based dynamic events by
using ftrace_event_file.

This patch is based kprobe-based dynamic events multibuffer
support work initially, commited by Masami(commit 41a7dd420c),
but revised as below:

Oleg changed the kprobe-based multibuffer design from
array-pointers of ftrace_event_file into simple list,
so this patch also change to the list design.

rcu_read_lock/unlock added into uprobe_trace_func/uretprobe_trace_func,
to synchronize with ftrace_event_file list add and delete.

Even though we allow multi-uprobes instances now,
but TP_FLAG_PROFILE/TP_FLAG_TRACE are still mutually exclusive
in probe_event_enable currently, this means we cannot allow
one user is using uprobe-tracer, and another user is using
perf-probe on same uprobe concurrently.
(Perhaps this will be fix in future, kprobe dont't have this
limitation now)

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---
 kernel/trace/trace_uprobe.c |  119 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 100 insertions(+), 19 deletions(-)

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 32494fb0..2fc9931 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -53,6 +53,7 @@ struct trace_uprobe {
 	struct list_head		list;
 	struct ftrace_event_class	class;
 	struct ftrace_event_call	call;
+	struct list_head		files;
 	struct trace_uprobe_filter	filter;
 	struct uprobe_consumer		consumer;
 	struct inode			*inode;
@@ -65,6 +66,11 @@ struct trace_uprobe {
 	struct probe_arg		args[];
 };

+struct event_file_link {
+	struct ftrace_event_file	*file;
+	struct list_head		list;
+};
+
 #define SIZEOF_TRACE_UPROBE(n)			\
 	(offsetof(struct trace_uprobe, args) +	\
 	(sizeof(struct probe_arg) * (n)))
@@ -124,6 +130,7 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
 		goto error;

 	INIT_LIST_HEAD(&tu->list);
+	INIT_LIST_HEAD(&tu->files);
 	tu->consumer.handler = uprobe_dispatcher;
 	if (is_ret)
 		tu->consumer.ret_handler = uretprobe_dispatcher;
@@ -511,7 +518,8 @@ static const struct file_operations uprobe_profile_ops = {
 };

 static void uprobe_trace_print(struct trace_uprobe *tu,
-				unsigned long func, struct pt_regs *regs)
+				unsigned long func, struct pt_regs *regs,
+				struct ftrace_event_file *ftrace_file)
 {
 	struct uprobe_trace_entry_head *entry;
 	struct ring_buffer_event *event;
@@ -520,9 +528,12 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
 	int size, i;
 	struct ftrace_event_call *call = &tu->call;

+	WARN_ON(call != ftrace_file->event_call);
+
 	size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
-	event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
-						  size + tu->size, 0, 0);
+	event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
+						call->event.type,
+						size + tu->size, 0, 0);
 	if (!event)
 		return;

@@ -546,15 +557,28 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
 /* uprobe handler */
 static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
 {
-	if (!is_ret_probe(tu))
-		uprobe_trace_print(tu, 0, regs);
+	struct event_file_link *link;
+
+	if (is_ret_probe(tu))
+		return 0;
+
+	rcu_read_lock();
+	list_for_each_entry(link, &tu->files, list)
+		uprobe_trace_print(tu, 0, regs, link->file);
+	rcu_read_unlock();
+
 	return 0;
 }

 static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
 				struct pt_regs *regs)
 {
-	uprobe_trace_print(tu, func, regs);
+	struct event_file_link *link;
+
+	rcu_read_lock();
+	list_for_each_entry(link, &tu->files, list)
+		uprobe_trace_print(tu, func, regs, link->file);
+	rcu_read_unlock();
 }

 /* Event entry printers */
@@ -605,33 +629,89 @@ typedef bool (*filter_func_t)(struct uprobe_consumer *self,
 				struct mm_struct *mm);

 static int
-probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
+probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file,
+		   filter_func_t filter)
 {
-	int ret = 0;
+	bool enabled = is_trace_uprobe_enabled(tu);
+	struct event_file_link *link;
+	int ret;
+
+	if (file) {
+		if (tu->flags & TP_FLAG_PROFILE)
+			return -EINTR;

-	if (is_trace_uprobe_enabled(tu))
-		return -EINTR;
+		link = kmalloc(sizeof(*link), GFP_KERNEL);
+		if (!link)
+			return -ENOMEM;
+
+		link->file = file;
+		list_add_tail_rcu(&link->list, &tu->files);
+
+		tu->flags |= TP_FLAG_TRACE;
+	} else {
+		if (tu->flags & TP_FLAG_TRACE)
+			return -EINTR;
+
+		tu->flags |= TP_FLAG_PROFILE;
+	}

 	WARN_ON(!uprobe_filter_is_empty(&tu->filter));

-	tu->flags |= flag;
+	if (enabled)
+		return 0;
+
 	tu->consumer.filter = filter;
 	ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
-	if (ret)
-		tu->flags &= ~flag;
+	if (ret) {
+		if (file) {
+			list_del(&link->list);
+			kfree(link);
+			tu->flags &= ~TP_FLAG_TRACE;
+		} else
+			tu->flags &= ~TP_FLAG_PROFILE;
+	}

 	return ret;
 }

-static void probe_event_disable(struct trace_uprobe *tu, int flag)
+static struct event_file_link *
+find_event_file_link(struct trace_uprobe *tu, struct ftrace_event_file *file)
+{
+	struct event_file_link *link;
+
+	list_for_each_entry(link, &tu->files, list)
+		if (link->file == file)
+			return link;
+
+	return NULL;
+}
+
+static void
+probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file)
 {
 	if (!is_trace_uprobe_enabled(tu))
 		return;

+	if (file) {
+		struct event_file_link *link;
+
+		link = find_event_file_link(tu, file);
+		if (!link)
+			return;
+
+		list_del_rcu(&link->list);
+		/* synchronize with uprobe_trace_func/uretprobe_trace_func */
+		synchronize_sched();
+		kfree(link);
+
+		if (!list_empty(&tu->files))
+			return;
+	}
+
 	WARN_ON(!uprobe_filter_is_empty(&tu->filter));

 	uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
-	tu->flags &= ~flag;
+	tu->flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
 }

 static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
@@ -867,21 +947,22 @@ static
 int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
 {
 	struct trace_uprobe *tu = event->data;
+	struct ftrace_event_file *file = data;

 	switch (type) {
 	case TRACE_REG_REGISTER:
-		return probe_event_enable(tu, TP_FLAG_TRACE, NULL);
+		return probe_event_enable(tu, file, NULL);

 	case TRACE_REG_UNREGISTER:
-		probe_event_disable(tu, TP_FLAG_TRACE);
+		probe_event_disable(tu, file);
 		return 0;

 #ifdef CONFIG_PERF_EVENTS
 	case TRACE_REG_PERF_REGISTER:
-		return probe_event_enable(tu, TP_FLAG_PROFILE, uprobe_perf_filter);
+		return probe_event_enable(tu, NULL, uprobe_perf_filter);

 	case TRACE_REG_PERF_UNREGISTER:
-		probe_event_disable(tu, TP_FLAG_PROFILE);
+		probe_event_disable(tu, NULL);
 		return 0;

 	case TRACE_REG_PERF_OPEN:
-- 1.7.9.7



^ permalink raw reply related	[flat|nested] 5+ messages in thread
* Re: [PATCH 1/2 v5 typo updated] tracing/uprobes: Support ftrace_event_file base multibuffer
  2013-07-04  7:01 ` [PATCH 1/2 v5 typo updated] " zhangwei(Jovi)
@ 2013-07-04  7:41   ` Namhyung Kim
  2013-07-04  8:02     ` zhangwei(Jovi)
  0 siblings, 1 reply; 5+ messages in thread
From: Namhyung Kim @ 2013-07-04  7:41 UTC (permalink / raw)
  To: zhangwei(Jovi)
  Cc: Steven Rostedt, Oleg Nesterov, Masami Hiramatsu,
	Frederic Weisbecker, Srikar Dronamraju, Ingo Molnar,
	linux-kernel

Hi Jovi,

Just a few of dummy questions..


On Thu, 4 Jul 2013 15:01:10 +0800, zhangwei wrote:
> Support multi-buffer on uprobe-based dynamic events by
> using ftrace_event_file.
>
> This patch is based kprobe-based dynamic events multibuffer
> support work initially, commited by Masami(commit 41a7dd420c),
> but revised as below:
>
> Oleg changed the kprobe-based multibuffer design from
> array-pointers of ftrace_event_file into simple list,
> so this patch also change to the list design.
>
> rcu_read_lock/unlock added into uprobe_trace_func/uretprobe_trace_func,
> to synchronize with ftrace_event_file list add and delete.
>
> Even though we allow multi-uprobes instances now,
> but TP_FLAG_PROFILE/TP_FLAG_TRACE are still mutually exclusive
> in probe_event_enable currently, this means we cannot allow
> one user is using uprobe-tracer, and another user is using
> perf-probe on same uprobe concurrently.
> (Perhaps this will be fix in future, kprobe dont't have this
> limitation now)

So why does this limitation exist?  Didn't we support this kind of thing
in the original code?

>
> Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> ---
[SNIP]
> +	rcu_read_lock();
> +	list_for_each_entry(link, &tu->files, list)

list_for_each_entry_rcu() ?


> +		uprobe_trace_print(tu, 0, regs, link->file);
> +	rcu_read_unlock();
> +
>  	return 0;
>  }
>
>  static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
>  				struct pt_regs *regs)
>  {
> -	uprobe_trace_print(tu, func, regs);
> +	struct event_file_link *link;
> +
> +	rcu_read_lock();
> +	list_for_each_entry(link, &tu->files, list)

Ditto.


> +		uprobe_trace_print(tu, func, regs, link->file);
> +	rcu_read_unlock();
>  }
[SNIP]
> -static void probe_event_disable(struct trace_uprobe *tu, int flag)
> +static struct event_file_link *
> +find_event_file_link(struct trace_uprobe *tu, struct ftrace_event_file *file)
> +{
> +	struct event_file_link *link;
> +
> +	list_for_each_entry(link, &tu->files, list)

Not sure of this case. ;)

Thanks,
Namhyung

> +		if (link->file == file)
> +			return link;
> +
> +	return NULL;
> +}
> +
> +static void
> +probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file)
>  {
>  	if (!is_trace_uprobe_enabled(tu))
>  		return;
>
> +	if (file) {
> +		struct event_file_link *link;
> +
> +		link = find_event_file_link(tu, file);
> +		if (!link)
> +			return;
> +
> +		list_del_rcu(&link->list);
> +		/* synchronize with uprobe_trace_func/uretprobe_trace_func */
> +		synchronize_sched();
> +		kfree(link);
> +
> +		if (!list_empty(&tu->files))
> +			return;
> +	}
> +
>  	WARN_ON(!uprobe_filter_is_empty(&tu->filter));
>
>  	uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
> -	tu->flags &= ~flag;
> +	tu->flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
>  }
>
>  static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
> @@ -867,21 +947,22 @@ static
>  int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
>  {
>  	struct trace_uprobe *tu = event->data;
> +	struct ftrace_event_file *file = data;
>
>  	switch (type) {
>  	case TRACE_REG_REGISTER:
> -		return probe_event_enable(tu, TP_FLAG_TRACE, NULL);
> +		return probe_event_enable(tu, file, NULL);
>
>  	case TRACE_REG_UNREGISTER:
> -		probe_event_disable(tu, TP_FLAG_TRACE);
> +		probe_event_disable(tu, file);
>  		return 0;
>
>  #ifdef CONFIG_PERF_EVENTS
>  	case TRACE_REG_PERF_REGISTER:
> -		return probe_event_enable(tu, TP_FLAG_PROFILE, uprobe_perf_filter);
> +		return probe_event_enable(tu, NULL, uprobe_perf_filter);
>
>  	case TRACE_REG_PERF_UNREGISTER:
> -		probe_event_disable(tu, TP_FLAG_PROFILE);
> +		probe_event_disable(tu, NULL);
>  		return 0;
>
>  	case TRACE_REG_PERF_OPEN:
> -- 1.7.9.7

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [PATCH 1/2 v5 typo updated] tracing/uprobes: Support ftrace_event_file base multibuffer
  2013-07-04  7:41   ` Namhyung Kim
@ 2013-07-04  8:02     ` zhangwei(Jovi)
  2013-07-04 17:57       ` Oleg Nesterov
  0 siblings, 1 reply; 5+ messages in thread
From: zhangwei(Jovi) @ 2013-07-04  8:02 UTC (permalink / raw)
  To: Namhyung Kim
  Cc: Steven Rostedt, Oleg Nesterov, Masami Hiramatsu,
	Frederic Weisbecker, Srikar Dronamraju, Ingo Molnar,
	linux-kernel

On 2013/7/4 15:41, Namhyung Kim wrote:
> Hi Jovi,
> 
> Just a few of dummy questions..
> 
> 
> On Thu, 4 Jul 2013 15:01:10 +0800, zhangwei wrote:
>> Support multi-buffer on uprobe-based dynamic events by
>> using ftrace_event_file.
>>
>> This patch is based kprobe-based dynamic events multibuffer
>> support work initially, commited by Masami(commit 41a7dd420c),
>> but revised as below:
>>
>> Oleg changed the kprobe-based multibuffer design from
>> array-pointers of ftrace_event_file into simple list,
>> so this patch also change to the list design.
>>
>> rcu_read_lock/unlock added into uprobe_trace_func/uretprobe_trace_func,
>> to synchronize with ftrace_event_file list add and delete.
>>
>> Even though we allow multi-uprobes instances now,
>> but TP_FLAG_PROFILE/TP_FLAG_TRACE are still mutually exclusive
>> in probe_event_enable currently, this means we cannot allow
>> one user is using uprobe-tracer, and another user is using
>> perf-probe on same uprobe concurrently.
>> (Perhaps this will be fix in future, kprobe dont't have this
>> limitation now)
> 
> So why does this limitation exist?  Didn't we support this kind of thing
> in the original code?
> 
Yes, it existed(maybe not exist before uprobe pre-filter work), because uprobe filter
is associated with trace_uprobe tightly at present, so we cannot assign
TP_FLAG_PROFILE/TP_FLAG_TRACE for same trace_uprobe with different filter.

Perhaps we need to remove the limitation in future.

>>
>> Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>> Cc: Oleg Nesterov <oleg@redhat.com>
>> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
>> ---
> [SNIP]
>> +	rcu_read_lock();
>> +	list_for_each_entry(link, &tu->files, list)
> 
> list_for_each_entry_rcu() ?
> 
I haven't noticed this, thanks, I will update it.
> 
>> +		uprobe_trace_print(tu, 0, regs, link->file);
>> +	rcu_read_unlock();
>> +
>>  	return 0;
>>  }
>>
>>  static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
>>  				struct pt_regs *regs)
>>  {
>> -	uprobe_trace_print(tu, func, regs);
>> +	struct event_file_link *link;
>> +
>> +	rcu_read_lock();
>> +	list_for_each_entry(link, &tu->files, list)
> 
> Ditto.
> 
> 
>> +		uprobe_trace_print(tu, func, regs, link->file);
>> +	rcu_read_unlock();
>>  }
> [SNIP]
>> -static void probe_event_disable(struct trace_uprobe *tu, int flag)
>> +static struct event_file_link *
>> +find_event_file_link(struct trace_uprobe *tu, struct ftrace_event_file *file)
>> +{
>> +	struct event_file_link *link;
>> +
>> +	list_for_each_entry(link, &tu->files, list)
> 
> Not sure of this case. ;)
> 
Yes, _rcu is not needed in here, it's only called in event disable serialized case.

> Thanks,
> Namhyung
> 
>> +		if (link->file == file)
>> +			return link;
>> +
>> +	return NULL;
>> +}
>> +
>> +static void
>> +probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file)
>>  {
>>  	if (!is_trace_uprobe_enabled(tu))
>>  		return;
>>
>> +	if (file) {
>> +		struct event_file_link *link;
>> +
>> +		link = find_event_file_link(tu, file);
>> +		if (!link)
>> +			return;
>> +
>> +		list_del_rcu(&link->list);
>> +		/* synchronize with uprobe_trace_func/uretprobe_trace_func */
>> +		synchronize_sched();
>> +		kfree(link);
>> +
>> +		if (!list_empty(&tu->files))
>> +			return;
>> +	}
>> +
>>  	WARN_ON(!uprobe_filter_is_empty(&tu->filter));
>>
>>  	uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
>> -	tu->flags &= ~flag;
>> +	tu->flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
>>  }
>>
>>  static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
>> @@ -867,21 +947,22 @@ static
>>  int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
>>  {
>>  	struct trace_uprobe *tu = event->data;
>> +	struct ftrace_event_file *file = data;
>>
>>  	switch (type) {
>>  	case TRACE_REG_REGISTER:
>> -		return probe_event_enable(tu, TP_FLAG_TRACE, NULL);
>> +		return probe_event_enable(tu, file, NULL);
>>
>>  	case TRACE_REG_UNREGISTER:
>> -		probe_event_disable(tu, TP_FLAG_TRACE);
>> +		probe_event_disable(tu, file);
>>  		return 0;
>>
>>  #ifdef CONFIG_PERF_EVENTS
>>  	case TRACE_REG_PERF_REGISTER:
>> -		return probe_event_enable(tu, TP_FLAG_PROFILE, uprobe_perf_filter);
>> +		return probe_event_enable(tu, NULL, uprobe_perf_filter);
>>
>>  	case TRACE_REG_PERF_UNREGISTER:
>> -		probe_event_disable(tu, TP_FLAG_PROFILE);
>> +		probe_event_disable(tu, NULL);
>>  		return 0;
>>
>>  	case TRACE_REG_PERF_OPEN:
>> -- 1.7.9.7
> 
> .
> 



^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [PATCH 1/2 v5 typo updated] tracing/uprobes: Support ftrace_event_file base multibuffer
  2013-07-04  8:02     ` zhangwei(Jovi)
@ 2013-07-04 17:57       ` Oleg Nesterov
  0 siblings, 0 replies; 5+ messages in thread
From: Oleg Nesterov @ 2013-07-04 17:57 UTC (permalink / raw)
  To: zhangwei(Jovi)
  Cc: Namhyung Kim, Steven Rostedt, Masami Hiramatsu,
	Frederic Weisbecker, Srikar Dronamraju, Ingo Molnar,
	linux-kernel

On 07/04, zhangwei(Jovi) wrote:
>
> On 2013/7/4 15:41, Namhyung Kim wrote:
> >>
> >> Even though we allow multi-uprobes instances now,
> >> but TP_FLAG_PROFILE/TP_FLAG_TRACE are still mutually exclusive
> >> in probe_event_enable currently, this means we cannot allow
> >> one user is using uprobe-tracer, and another user is using
> >> perf-probe on same uprobe concurrently.
> >> (Perhaps this will be fix in future, kprobe dont't have this
> >> limitation now)
> >
> > So why does this limitation exist?  Didn't we support this kind of thing
> > in the original code?

For no reason.

> Yes, it existed(maybe not exist before uprobe pre-filter work),

No, it was always here and I never understood it.

> because uprobe filter
> is associated with trace_uprobe tightly at present, so we cannot assign
> TP_FLAG_PROFILE/TP_FLAG_TRACE for same trace_uprobe with different filter.

More precisely, TRACE_REG_REGISTER should participate (inc/dec nr_systemwide)
if CONFIG_PERF_EVENTS.

> Perhaps we need to remove the limitation in future.

Yes, I'll remove it.

Oleg.


^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2013-07-04 18:01 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-07-04  6:53 [PATCH 1/2 v5] tracing/uprobes: Support ftrace_event_file base multibuffer zhangwei(Jovi)
2013-07-04  7:01 ` [PATCH 1/2 v5 typo updated] " zhangwei(Jovi)
2013-07-04  7:41   ` Namhyung Kim
2013-07-04  8:02     ` zhangwei(Jovi)
2013-07-04 17:57       ` Oleg Nesterov

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