Op 27-05-13 10:00, Peter Zijlstra schreef: > 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? > It's easy to merge unlock_single and unlock, which I did in the next version I'll post. Lockdep will already warn if ww_mutex_lock and ww_mutex_lock_single are both used. ww_test_block_context and ww_test_context_block in lib/locking-selftest.c are the testcases for this. The locking paths are too different, it will end up with doing "if (ctx == NULL) mutex_lock(); else ww_mutex_lock();" ~Maarten _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
