Re: [PATCH 3/5 v2] tracing: Automatically mount tracefs on debugfs/tracing

From: Steven Rostedt
Date: Sun Jan 25 2015 - 14:38:40 EST


On Sun, 25 Jan 2015 21:22:07 +0800
Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:


> If we could do it in a non-racy way, that would be good, otherwise I
> don't see us being able to even take this patch :(

Is it still racy even if it's only done at boot up? This path only gets
hit the first time it is called. "if (tr->flags &TRACE_ARRAY_FL_GLOBAL)"
is the top level tracing directory ("tracing") and is only called
during boot up (fs_initcall) and never hit again. I could even make
this called directly by that code so we could label it "__init" to make
sure that it is to be never hit. Or is this racy even when done by
fs_initcall?

Waiting for Al to comment on this, because, I can't add this feature
until debugfs/tracing still containing the tracing information,
otherwise it will break all the tools that interact with the tracing
infrastructure, and we all know how happy Linus feels about such
changes.

-- Steve
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