Re: [PATCH v4 05/15] lockdep: Make check_prev_add can use a separate stack_trace

Byungchul Park
2017-01-13T02:45:27Z

On Thu, Jan 12, 2017 at 05:16:43PM +0100, Peter Zijlstra wrote:
> On Fri, Dec 09, 2016 at 02:12:01PM +0900, Byungchul Park wrote:
> > check_prev_add() saves a stack trace of the current. But crossrelease
> > feature needs to use a separate stack trace of another context in
> > check_prev_add(). So make it use a separate stack trace instead of one
> > of the current.
> >
>
> So I was thinking, can't we make check_prevs_add() create the stack
> trace unconditionally but record if we used it or not, and then return
> the entries when unused. All that is serialized by graph_lock anyway and
> that way we already pass a stack into check_prev_add() so we can easily
> pass in a different one.
>
> I think that removes a bunch of tricky and avoids all the new tricky.

Looks very good.