From: Steven Rostedt <rostedt@goodmis.org>
To: Yang Jihong <yangjihong1@huawei.com>
Cc: <mingo@redhat.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] tracing: save cmdline only when task does not exist in savecmd for optimization
Date: Thu, 14 Oct 2021 10:32:01 -0400 [thread overview]
Message-ID: <20211014103201.685d3647@gandalf.local.home> (raw)
In-Reply-To: <20211011115018.88948-1-yangjihong1@huawei.com>
On Mon, 11 Oct 2021 19:50:18 +0800
Yang Jihong <yangjihong1@huawei.com> wrote:
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 7896d30d90f7..a795610a3b37 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -2427,8 +2427,11 @@ static int trace_save_cmdline(struct task_struct *tsk)
> savedcmd->cmdline_idx = idx;
> }
>
> - savedcmd->map_cmdline_to_pid[idx] = tsk->pid;
> - set_cmdline(idx, tsk->comm);
> + /* save cmdline only when task does not exist in savecmd */
> + if (savedcmd->map_cmdline_to_pid[idx] != tsk->pid) {
> + savedcmd->map_cmdline_to_pid[idx] = tsk->pid;
> + set_cmdline(idx, tsk->comm);
> + }
>
I now remember why I never did it this way. This breaks saving the command
line when we do an exec.
That is, just because mapped_pid == tsk->pid does not mean that the comm is
the same.
-- Steve
next prev parent reply other threads:[~2021-10-14 14:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-11 11:50 [PATCH] tracing: save cmdline only when task does not exist in savecmd for optimization Yang Jihong
2021-10-14 3:02 ` Steven Rostedt
2021-10-14 8:09 ` Yang Jihong
2021-10-14 14:32 ` Steven Rostedt [this message]
2021-10-15 1:27 ` Yang Jihong
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