Messages in this thread | | | Date | Fri, 5 Jun 2015 11:55:52 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 13/14] lockdep: Implement lock pinning |
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* Peter Zijlstra <peterz@infradead.org> wrote:
> RFC: a possible alternative API would be something like: > > int cookie = lockdep_pin_lock(&foo); > ... > lockdep_unpin_lock(&foo, cookie);
Yeah, this would be even nicer.
> Where we pick a random number for the pin_count; this makes it > impossible to sneak a lock break in without also passing the right > cookie along. > > I've not done this because it ends up generating code for !LOCKDEP, > esp. if you need to pass the cookie around for some reason.
The cookie could be a zero-size structure, which can be 'passed around' syntactically but creates no overhead in the code.
But I'd expect cookie-passing to be a sign of badness in most cases: the lock should generally be unpinned at the same level of abstraction...
Thanks,
Ingo
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