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Date: Tue, 27 Jan 2015 04:38:39 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 00/16 v3] tracing: Add new file system tracefs
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On Mon, Jan 26, 2015 at 08:03:50PM -0500, Steven Rostedt wrote:
> On Mon, 26 Jan 2015 20:02:18 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> 
> > Now you see why I found just dropping the parent mutex easier.
> 
> And this is probably why kernfs does things the way it does. I can
> imagine it having the same locking issues.

The least said about kernfs locking, the better...

As for the use of trace_types_lock to serialize rmdir vs. event
addition/removal, I wonder what's wrong with actually using the
->i_mutex of /instances - you have a reference to its dentry,
after all...