Messages in this thread | | | Date | Tue, 28 Mar 2006 23:42:20 +0200 | From | Zoltan Menyhart <> | Subject | Re: Fix unlock_buffer() to work the same way as bit_unlock() |
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Chen, Kenneth W wrote: > Nick Piggin wrote on Tuesday, March 28, 2006 12:11 AM > >>Also, I think there is still the issue of ia64 not having the >>correct memory consistency semantics. To start with, all the bitops >>and atomic ops which both modify their operand and return a value >>should be full memory barriers before and after the operation, >>according to Documentation/atomic_ops.txt. > > I suppose the usage of atomic ops is abused, it is used in both lock > and unlock path. And it naturally suck because it now requires full > memory barrier. A better way is to define 3 variants: one for lock > path, one for unlock path, and one with full memory fence.
I agree. As I wrote a few days ago:
Why not to use separate bit operations for different purposes?
- e.g. "test_and_set_bit_N_acquire()" for lock acquisition - "test_and_set_bit()", "clear_bit()" as they are today - "release_N_clear_bit()"...
Thanks,
Zoltan
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