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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 18:45:24 -0400	[thread overview]
Message-ID: <20220907184524.0dfb3a8a@gandalf.local.home> (raw)
In-Reply-To: <YxkS5uzouv2bn6ZB@google.com>

On Wed, 7 Sep 2022 14:53:42 -0700
Brian Norris <briannorris@chromium.org> wrote:

> Try these:
> 
>   umount /sys/kernel/debug/tracing/
>   grep tracefs /proc/mounts
>   stat /sys/kernel/debug/tracing/.
>   grep tracefs /proc/mounts
> 
> The first and the second grep will give you different results.

How about this:

  # grep tracefs /proc/mounts
tracefs /sys/kernel/tracing tracefs rw,nosuid,nodev,noexec,relatime 0 0
tracefs /sys/kernel/debug/tracing tracefs rw,nosuid,nodev,noexec,relatime 0 0

 # umount /sys/kernel/debug/tracing 
 # grep tracefs /proc/mounts
tracefs /sys/kernel/tracing tracefs rw,nosuid,nodev,noexec,relatime 0 0

 # ls /sys/kernel/debug/tracing
available_events            hwlat_detector       set_event_notrace_pid   trace_clock
available_filter_functions  instances            set_event_pid           trace_marker
available_tracers           kprobe_events        set_ftrace_filter       trace_marker_raw
buffer_percent              kprobe_profile       set_ftrace_notrace      trace_options
buffer_size_kb              max_graph_depth      set_ftrace_notrace_pid  trace_pipe
buffer_total_size_kb        options              set_ftrace_pid          trace_stat
current_tracer              osnoise              set_graph_function      tracing_cpumask
dynamic_events              per_cpu              set_graph_notrace       tracing_max_latency
dyn_ftrace_total_info       printk_formats       snapshot                tracing_on
enabled_functions           README               stack_max_size          tracing_thresh
error_log                   recursed_functions   stack_trace             uprobe_events
eval_map                    saved_cmdlines       stack_trace_filter      uprobe_profile
events                      saved_cmdlines_size  synthetic_events        user_events_data
free_buffer                 saved_tgids          timestamp_mode          user_events_status
function_profile_enabled    set_event            trace

 # grep tracefs /proc/mounts
tracefs /sys/kernel/tracing tracefs rw,nosuid,nodev,noexec,relatime 0 0
tracefs /sys/kernel/debug/tracing tracefs rw,nosuid,nodev,noexec,relatime 0 0

So it appears that accessing debugfs/tracing will automatically remount it.

Lean something new everyday! ;-)

-- Steve

  reply	other threads:[~2022-09-07 22:44 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
2022-09-07 21:48     ` Steven Rostedt
2022-09-07 21:53       ` Brian Norris
2022-09-07 22:45         ` Steven Rostedt [this message]
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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