netdev - Re: [PATCH v3 09/11] tracing: Replace strncpy() with __get_task

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Date: Fri, 21 Jun 2024 13:37:42 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Yafang Shao <laoar.shao@...il.com>
Cc: torvalds@...ux-foundation.org, ebiederm@...ssion.com,
 alexei.starovoitov@...il.com, rostedt@...dmis.org, catalin.marinas@....com,
 akpm@...ux-foundation.org, penguin-kernel@...ove.sakura.ne.jp,
 linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, audit@...r.kernel.org,
 linux-security-module@...r.kernel.org, selinux@...r.kernel.org,
 bpf@...r.kernel.org, netdev@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, Masami Hiramatsu <mhiramat@...nel.org>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [PATCH v3 09/11] tracing: Replace strncpy() with
 __get_task_comm()

On Fri, 21 Jun 2024 10:29:57 +0800
Yafang Shao <laoar.shao@...il.com> wrote:

> Using __get_task_comm() to read the task comm ensures that the name is
> always NUL-terminated, regardless of the source string. This approach also
> facilitates future extensions to the task comm.

Good catch! Looks good to me.

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

Thank you,

> 
> Signed-off-by: Yafang Shao <laoar.shao@...il.com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> ---
>  kernel/trace/trace.c             | 2 +-
>  kernel/trace/trace_events_hist.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 578a49ff5c32..ce94a86154a2 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -1907,7 +1907,7 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
>  	max_data->critical_start = data->critical_start;
>  	max_data->critical_end = data->critical_end;
>  
> -	strncpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
> +	__get_task_comm(max_data->comm, TASK_COMM_LEN, tsk);
>  	max_data->pid = tsk->pid;
>  	/*
>  	 * If tsk == current, then use current_uid(), as that does not use
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 6ece1308d36a..721d4758a79f 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -1599,7 +1599,7 @@ static inline void save_comm(char *comm, struct task_struct *task)
>  		return;
>  	}
>  
> -	strncpy(comm, task->comm, TASK_COMM_LEN);
> +	__get_task_comm(comm, TASK_COMM_LEN, task);
>  }
>  
>  static void hist_elt_data_free(struct hist_elt_data *elt_data)
> -- 
> 2.39.1
> 


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