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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 21:25:42 -0400	[thread overview]
Message-ID: <20220907212542.513afad2@gandalf.local.home> (raw)
In-Reply-To: <YxkEfzVusTXj9JST@google.com>

On Wed, 7 Sep 2022 13:52:15 -0700
Brian Norris <briannorris@chromium.org> wrote:

> Existing behavior:
> 
>   ## Pre-existing status: tracefs is 0755.
>   # stat -c '%A' /sys/kernel/tracing/
>   drwxr-xr-x
> 
>   ## (Re)trigger the automount.
>   # umount /sys/kernel/debug/tracing
>   # stat -c '%A' /sys/kernel/debug/tracing/.
>   drwx------
> 
>   ## Unexpected: the automount changed mode for other mount instances.
>   # stat -c '%A' /sys/kernel/tracing/
>   drwx------
> 
> New behavior:
> 
>   ## Pre-existing status: tracefs is 0755.
>   # stat -c '%A' /sys/kernel/tracing/
>   drwxr-xr-x
> 
>   ## (Re)trigger the automount.
>   # umount /sys/kernel/debug/tracing
>   # stat -c '%A' /sys/kernel/debug/tracing/.
>   drwxr-xr-x
> 
>   ## Expected: the automount does not change other mount instances.
>   # stat -c '%A' /sys/kernel/tracing/
>   drwxr-xr-x

Thanks!

Here's the new change log:

-- Steve

From: Brian Norris <briannorris@chromium.org>
Subject: [PATCH] tracefs: Only clobber mode/uid/gid on remount if asked

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/.

Existing behavior:

  ## Pre-existing status: tracefs is 0755.
  # stat -c '%A' /sys/kernel/tracing/
  drwxr-xr-x

  ## (Re)trigger the automount.
  # umount /sys/kernel/debug/tracing
  # stat -c '%A' /sys/kernel/debug/tracing/.
  drwx------

  ## Unexpected: the automount changed mode for other mount instances.
  # stat -c '%A' /sys/kernel/tracing/
  drwx------

New behavior (after this change):

  ## Pre-existing status: tracefs is 0755.
  # stat -c '%A' /sys/kernel/tracing/
  drwxr-xr-x

  ## (Re)trigger the automount.
  # umount /sys/kernel/debug/tracing
  # stat -c '%A' /sys/kernel/debug/tracing/.
  drwxr-xr-x

  ## Expected: the automount does not change other mount instances.
  # stat -c '%A' /sys/kernel/tracing/
  drwxr-xr-x


Signed-off-by: Brian Norris <briannorris@chromium.org>

  reply	other threads:[~2022-09-08  1:25 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 [this message]
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
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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