From: Steven Rostedt <rostedt@goodmis.org>
To: Brian Norris <briannorris@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] tracefs: Only clobber mode/uid/gid on remount if asked
Date: Wed, 7 Sep 2022 17:46:04 -0400 [thread overview]
Message-ID: <20220907174604.06809ff2@gandalf.local.home> (raw)
In-Reply-To: <20220826174353.2.Iab6e5ea57963d6deca5311b27fb7226790d44406@changeid>
On Fri, 26 Aug 2022 17:44:17 -0700
Brian Norris <briannorris@chromium.org> wrote:
> Users may have explicitly configured their tracefs permissions; we
> shouldn't overwrite those just because a second mount appeared.
>
> Only clobber if the options were provided at mount time.
>
> Note: the previous behavior was especially surprising in the presence of
> automounted /sys/kernel/debug/tracing/.
>
> # Don't change /sys/kernel/tracing/ permissions on automount.
> umount /sys/kernel/debug/tracing/
BTW, I noticed that the above doesn't do anything. That is,
you cannot unmount tracefs from /sys/kernel/debug/tracing.
# ls /sys/kernel/debug/tracing/
available_events buffer_total_size_kb error_log hwlat_detector options recursed_functions set_event_notrace_pid set_ftrace_pid stack_trace trace_clock trace_stat uprobe_events
available_filter_functions current_tracer eval_map instances osnoise saved_cmdlines set_event_pid set_graph_function stack_trace_filter trace_marker tracing_cpumask uprobe_profile
available_tracers dynamic_events events kprobe_events per_cpu saved_cmdlines_size set_ftrace_filter set_graph_notrace synthetic_events trace_marker_raw tracing_max_latency user_events_data
buffer_percent dyn_ftrace_total_info free_buffer kprobe_profile printk_formats saved_tgids set_ftrace_notrace snapshot timestamp_mode trace_options tracing_on user_events_status
buffer_size_kb enabled_functions function_profile_enabled max_graph_depth README set_event set_ftrace_notrace_pid stack_max_size trace trace_pipe tracing_thresh
# umount /sys/kernel/debug/tracing/
# ls /sys/kernel/debug/tracing/
available_events buffer_total_size_kb error_log hwlat_detector options recursed_functions set_event_notrace_pid set_ftrace_pid stack_trace trace_clock trace_stat uprobe_events
available_filter_functions current_tracer eval_map instances osnoise saved_cmdlines set_event_pid set_graph_function stack_trace_filter trace_marker tracing_cpumask uprobe_profile
available_tracers dynamic_events events kprobe_events per_cpu saved_cmdlines_size set_ftrace_filter set_graph_notrace synthetic_events trace_marker_raw tracing_max_latency user_events_data
buffer_percent dyn_ftrace_total_info free_buffer kprobe_profile printk_formats saved_tgids set_ftrace_notrace snapshot timestamp_mode trace_options tracing_on user_events_status
buffer_size_kb enabled_functions function_profile_enabled max_graph_depth README set_event set_ftrace_notrace_pid stack_max_size trace trace_pipe tracing_thresh
-- Steve
> stat /sys/kernel/debug/tracing/.
>
> # Don't change /sys/kernel/tracing/ permissions.
> mount -t tracefs none /mnt/foo
>
> # Change /sys/kernel/tracing/ mode and uid, but not gid.
> mount -t tracefs -o uid=bar,mode=0750 none /mnt/baz
>
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
>
next prev parent reply other threads:[~2022-09-07 21:45 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-27 0:44 [PATCH 1/2] debugfs: Only clobber mode/uid/gid on remount if asked Brian Norris
2022-08-27 0:44 ` [PATCH 2/2] tracefs: " Brian Norris
2022-09-07 11:44 ` Steven Rostedt
2022-09-07 20:52 ` Brian Norris
2022-09-08 1:25 ` Steven Rostedt
2022-09-07 21:46 ` Steven Rostedt [this message]
2022-09-07 21:48 ` Steven Rostedt
2022-09-07 21:53 ` Brian Norris
2022-09-07 22:45 ` Steven Rostedt
2022-09-01 15:58 ` [PATCH 1/2] debugfs: " Greg Kroah-Hartman
2022-09-01 16:11 ` Steven Rostedt
2022-09-01 22:32 ` Brian Norris
2022-09-02 5:45 ` Greg Kroah-Hartman
2022-09-09 0:16 ` Brian Norris
2022-09-09 0:43 ` Steven Rostedt
2022-09-09 0:57 ` Brian Norris
2022-09-09 1:05 ` Steven Rostedt
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