[RFC PATCH] tracing: Revert "tracing: Remove pid in task_rename tracing output"

[RFC PATCH] tracing: Revert "tracing: Remove pid in task_rename tracing output"

[Xuewen Yan]

This reverts commit e3f6a42272e028c46695acc83fc7d7c42f2750ad.

The commit says that the tracepoint only deals with the current task,
however the following case is not current task:

comm_write
set_task_comm
__set_task_comm
trace_task_rename

So revert the patch to show pid.

Fixes: e3f6a42272e0 ("tracing: Remove pid in task_rename tracing output")
Reported-by: Guohua Yan <guohua.yan@unisoc.com>
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
---
 include/trace/events/task.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/trace/events/task.h b/include/trace/events/task.h
index 4f0759634306..b9a129eb54d9 100644
--- a/include/trace/events/task.h
+++ b/include/trace/events/task.h
@@ -38,19 +38,22 @@ TRACE_EVENT(task_rename,
 	TP_ARGS(task, comm),
 
 	TP_STRUCT__entry(
+		__field(	pid_t,	pid)
 		__array(	char, oldcomm,  TASK_COMM_LEN)
 		__array(	char, newcomm,  TASK_COMM_LEN)
 		__field(	short,	oom_score_adj)
 	),
 
 	TP_fast_assign(
+		__entry->pid = task->pid;
 		memcpy(entry->oldcomm, task->comm, TASK_COMM_LEN);
 		strscpy(entry->newcomm, comm, TASK_COMM_LEN);
 		__entry->oom_score_adj = task->signal->oom_score_adj;
 	),
 
-	TP_printk("oldcomm=%s newcomm=%s oom_score_adj=%hd",
-		  __entry->oldcomm, __entry->newcomm, __entry->oom_score_adj)
+	TP_printk("pid=%d oldcomm=%s newcomm=%s oom_score_adj=%hd",
+		__entry->pid, __entry->oldcomm,
+		__entry->newcomm, __entry->oom_score_adj)
 );
 
 /**
-- 
2.25.1

Re: [RFC PATCH] tracing: Revert "tracing: Remove pid in task_rename tracing output"

[Steven Rostedt]

On Thu, 5 Mar 2026 16:08:09 +0800
Xuewen Yan <xuewen.yan@unisoc.com> wrote:

> This reverts commit e3f6a42272e028c46695acc83fc7d7c42f2750ad.
> 
> The commit says that the tracepoint only deals with the current task,
> however the following case is not current task:
> 
> comm_write
> set_task_comm
> __set_task_comm
> trace_task_rename

I'm fine with the patch, but the change log can use a bit of work:

  comm_write() {
	p = get_proc_task(inode);
	if (!p)
		return -ESRCH;

	if (same_thread_group(current, p)) {
		set_task_comm(p, buffer);

  where set_task_comm() calls __set_task_comm() which records the update of
  p and not current.

The above states exactly why current isn't the pid that should be recorded.

Other than that.

Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

-- Steve


> 
> So revert the patch to show pid.
> 
> Fixes: e3f6a42272e0 ("tracing: Remove pid in task_rename tracing output")
> Reported-by: Guohua Yan <guohua.yan@unisoc.com>
> Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
> ---
>  include/trace/events/task.h | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/include/trace/events/task.h b/include/trace/events/task.h
> index 4f0759634306..b9a129eb54d9 100644
> --- a/include/trace/events/task.h
> +++ b/include/trace/events/task.h
> @@ -38,19 +38,22 @@ TRACE_EVENT(task_rename,
>  	TP_ARGS(task, comm),
>  
>  	TP_STRUCT__entry(
> +		__field(	pid_t,	pid)
>  		__array(	char, oldcomm,  TASK_COMM_LEN)
>  		__array(	char, newcomm,  TASK_COMM_LEN)
>  		__field(	short,	oom_score_adj)
>  	),
>  
>  	TP_fast_assign(
> +		__entry->pid = task->pid;
>  		memcpy(entry->oldcomm, task->comm, TASK_COMM_LEN);
>  		strscpy(entry->newcomm, comm, TASK_COMM_LEN);
>  		__entry->oom_score_adj = task->signal->oom_score_adj;
>  	),
>  
> -	TP_printk("oldcomm=%s newcomm=%s oom_score_adj=%hd",
> -		  __entry->oldcomm, __entry->newcomm, __entry->oom_score_adj)
> +	TP_printk("pid=%d oldcomm=%s newcomm=%s oom_score_adj=%hd",
> +		__entry->pid, __entry->oldcomm,
> +		__entry->newcomm, __entry->oom_score_adj)
>  );
>  
>  /**