Messages in this thread | | | Date | Fri, 31 Mar 2006 10:44:01 +1000 | From | Nick Piggin <> | Subject | Re: Synchronizing Bit operations V2 |
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Christoph Lameter wrote: > Changelog: > > V2 > - Fix various oversights > - Follow Hans Boehm's scheme for the barrier logic > > The following patchset implements the ability to specify a > synchronization mode for bit operations. > > I.e. instead of set_bit(x,y) we can do set_bit(x,y, mode). > > The following modes are supported: >
This has acquire and release, instead of the generic kernel memory barriers rmb and wmb. As such, I don't think it would get merged.
> Note that the current semantics for bitops IA64 are broken. Both > smp_mb__after/before_clear_bit are now set to full memory barriers > to compensate which may affect performance.
I think you should fight the fights you can win and get a 90% solution ;) at any rate you do need to fix the existing routines unless you plan to audit all callers...
First, fix up ia64 in 2.6-head, this means fixing test_and_set_bit and friends, smp_mb__*_clear_bit, and all the atomic operations that both modify and return a value.
Then add test_and_set_bit_lock / clear_bit_unlock, and apply them to a couple of critical places like page lock and buffer lock.
Is this being planned?
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