Re: [PATCH 03/11] ftrace: Cleanup regex_lock and ftrace_lock aroundhash updating

From: Steven Rostedt
Date: Thu May 09 2013 - 13:12:23 EST


On Thu, 2013-05-09 at 14:44 +0900, Masami Hiramatsu wrote:
> Cleanup regex_lock and ftrace_lock locking points around
> ftrace_ops hash update code.
>
> The new rule is that regex_lock protects ops->*_hash
> read-update-write code for each ftrace_ops. Usually,
> hash update is done by following sequence.
>
> 1. allocate a new local hash and copy the original hash.
> 2. update the local hash.
> 3. move(actually, copy) back the local hash to ftrace_ops.
> 4. update ftrace entries if needed.
> 5. release the local hash.
>
> This makes regex_lock to protect #1-#4, and ftrace_lock
> to protect #3 and #4.

Patch looks good, but I don't see how ftrace_lock protects #3. The two
things that I see ftrace_lock protecting is the update to the ftrace
entries, and the adding and removing ftrace_ops to the ftrace_ops_list.

-- Steve

>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Tom Zanussi <tom.zanussi@xxxxxxxxx>
> ---


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