Messages in this thread | | | Date | Mon, 27 May 2013 10:00:19 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 2/3] mutex: add support for wound/wait style locks, v3 |
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On Wed, May 22, 2013 at 07:24:38PM +0200, Maarten Lankhorst wrote: > >> +- Functions to only acquire a single w/w mutex, which results in the exact same > >> + semantics as a normal mutex. These functions have the _single postfix. > > This is missing rationale.
> trylock_single is useful when iterating over a list, and you want to evict a bo, but only the first one that can be acquired. > lock_single is useful when only a single bo needs to be acquired, for example to lock a buffer during mmap.
OK, so given that its still early, monday and I haven't actually spend much time thinking on this; would it be possible to make: ww_mutex_lock(.ctx=NULL) act like ww_mutex_lock_single()?
The idea is that if we don't provide a ctx, we'll get a different lockdep annotation; mutex_lock() vs mutex_lock_nest_lock(). So if we then go and make a mistake, lockdep should warn us.
Would that work or should I stock up on morning juice?
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