tracing: Use refcount for trace_event_file reference counter

[PATCH] tracing: Use refcount for trace_event_file reference counter

Posted by Steven Rostedt 1 year, 6 months ago

From: Steven Rostedt <rostedt@goodmis.org>

Instead of using an atomic counter for the trace_event_file reference
counter, use the refcount interface. It has various checks to make sure
the reference counting is correct, and will warn if it detects an error
(like refcount_inc() on '0').

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 include/linux/trace_events.h | 2 +-
 kernel/trace/trace_events.c  | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 9df3e2973626..fed58e54f15e 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -680,7 +680,7 @@ struct trace_event_file {
 	 * caching and such. Which is mostly OK ;-)
 	 */
 	unsigned long		flags;
-	atomic_t		ref;	/* ref count for opened files */
+	refcount_t		ref;	/* ref count for opened files */
 	atomic_t		sm_ref;	/* soft-mode reference counter */
 	atomic_t		tm_ref;	/* trigger-mode reference counter */
 };
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 852643d957de..81ade9ddcbe5 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -992,18 +992,18 @@ static void remove_subsystem(struct trace_subsystem_dir *dir)
 
 void event_file_get(struct trace_event_file *file)
 {
-	atomic_inc(&file->ref);
+	refcount_inc(&file->ref);
 }
 
 void event_file_put(struct trace_event_file *file)
 {
-	if (WARN_ON_ONCE(!atomic_read(&file->ref))) {
+	if (WARN_ON_ONCE(!refcount_read(&file->ref))) {
 		if (file->flags & EVENT_FILE_FL_FREED)
 			kmem_cache_free(file_cachep, file);
 		return;
 	}
 
-	if (atomic_dec_and_test(&file->ref)) {
+	if (refcount_dec_and_test(&file->ref)) {
 		/* Count should only go to zero when it is freed */
 		if (WARN_ON_ONCE(!(file->flags & EVENT_FILE_FL_FREED)))
 			return;
@@ -2999,7 +2999,7 @@ trace_create_new_event(struct trace_event_call *call,
 	atomic_set(&file->tm_ref, 0);
 	INIT_LIST_HEAD(&file->triggers);
 	list_add(&file->list, &tr->events);
-	event_file_get(file);
+	refcount_set(&file->ref, 1);
 
 	return file;
 }
-- 
2.43.0

Re: [PATCH] tracing: Use refcount for trace_event_file reference counter

Posted by Masami Hiramatsu (Google) 1 year, 6 months ago

On Fri, 26 Jul 2024 14:42:08 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: Steven Rostedt <rostedt@goodmis.org>
> 
> Instead of using an atomic counter for the trace_event_file reference
> counter, use the refcount interface. It has various checks to make sure
> the reference counting is correct, and will warn if it detects an error
> (like refcount_inc() on '0').
> 
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Looks good to me.

Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thanks,

> ---
>  include/linux/trace_events.h | 2 +-
>  kernel/trace/trace_events.c  | 8 ++++----
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> index 9df3e2973626..fed58e54f15e 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -680,7 +680,7 @@ struct trace_event_file {
>  	 * caching and such. Which is mostly OK ;-)
>  	 */
>  	unsigned long		flags;
> -	atomic_t		ref;	/* ref count for opened files */
> +	refcount_t		ref;	/* ref count for opened files */
>  	atomic_t		sm_ref;	/* soft-mode reference counter */
>  	atomic_t		tm_ref;	/* trigger-mode reference counter */
>  };
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 852643d957de..81ade9ddcbe5 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -992,18 +992,18 @@ static void remove_subsystem(struct trace_subsystem_dir *dir)
>  
>  void event_file_get(struct trace_event_file *file)
>  {
> -	atomic_inc(&file->ref);
> +	refcount_inc(&file->ref);
>  }
>  
>  void event_file_put(struct trace_event_file *file)
>  {
> -	if (WARN_ON_ONCE(!atomic_read(&file->ref))) {
> +	if (WARN_ON_ONCE(!refcount_read(&file->ref))) {
>  		if (file->flags & EVENT_FILE_FL_FREED)
>  			kmem_cache_free(file_cachep, file);
>  		return;
>  	}
>  
> -	if (atomic_dec_and_test(&file->ref)) {
> +	if (refcount_dec_and_test(&file->ref)) {
>  		/* Count should only go to zero when it is freed */
>  		if (WARN_ON_ONCE(!(file->flags & EVENT_FILE_FL_FREED)))
>  			return;
> @@ -2999,7 +2999,7 @@ trace_create_new_event(struct trace_event_call *call,
>  	atomic_set(&file->tm_ref, 0);
>  	INIT_LIST_HEAD(&file->triggers);
>  	list_add(&file->list, &tr->events);
> -	event_file_get(file);
> +	refcount_set(&file->ref, 1);
>  
>  	return file;
>  }
> -- 
> 2.43.0
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

Re: [PATCH] tracing: Use refcount for trace_event_file reference counter

Posted by Steven Rostedt 1 year, 6 months ago

On Mon, 29 Jul 2024 23:49:24 +0900
Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:

> On Fri, 26 Jul 2024 14:42:08 -0400
> Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> > From: Steven Rostedt <rostedt@goodmis.org>
> > 
> > Instead of using an atomic counter for the trace_event_file reference
> > counter, use the refcount interface. It has various checks to make sure
> > the reference counting is correct, and will warn if it detects an error
> > (like refcount_inc() on '0').
> > 
> > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>  
> 
> Looks good to me.
> 
> Masami Hiramatsu (Google) <mhiramat@kernel.org>

Is that an ack or a review? ;-)

-- Steve

Re: [PATCH] tracing: Use refcount for trace_event_file reference counter

Posted by Masami Hiramatsu (Google) 1 year, 6 months ago

On Mon, 29 Jul 2024 19:02:41 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Mon, 29 Jul 2024 23:49:24 +0900
> Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
> 
> > On Fri, 26 Jul 2024 14:42:08 -0400
> > Steven Rostedt <rostedt@goodmis.org> wrote:
> > 
> > > From: Steven Rostedt <rostedt@goodmis.org>
> > > 
> > > Instead of using an atomic counter for the trace_event_file reference
> > > counter, use the refcount interface. It has various checks to make sure
> > > the reference counting is correct, and will warn if it detects an error
> > > (like refcount_inc() on '0').
> > > 
> > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>  
> > 
> > Looks good to me.
> > 
> > Masami Hiramatsu (Google) <mhiramat@kernel.org>
> 
> Is that an ack or a review? ;-)

It was Ack,

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Sorry about that. I might be too sleep.

> 
> -- Steve
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>