Messages in this thread | | | Date | Wed, 20 Jan 2010 16:55:42 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [x86] Unify semaphore_32.S and rwlock_64.S |
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On 01/20/2010 04:46 PM, Linus Torvalds wrote: > > > On Wed, 20 Jan 2010, Linus Torvalds wrote: >> >> #define RWSEM_UNLOCKED_VALUE 0x00000000 >> #define RWSEM_ACTIVE_BIAS 0x00000001 >> #define RWSEM_ACTIVE_MASK 0x3fffffff >> #define RWSEM_WAITING_BIAS (~RWSEM_ACTIVE_MASK) >> #define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS >> #define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) > > Btw, doing that RWSEM_WAITING_BIAS cleanup (we currently have it as an > independent constant) means that now all constants are shared except for > that RWSEM_ACTIVE_MASK. So it ends up being something like this: > > #ifdef CONFIG_RWSEM_64bit > typedef __s64 rwsem_count_t; > #define RWSEM_ACTIVE_MASK 0x3fffffff > #else > typedef __s32 rwsem_count_t; > #define RWSEM_ACTIVE_MASK 0xffff > #endif > > #define RWSEM_UNLOCKED_VALUE 0x00000000 > #define RWSEM_ACTIVE_BIAS 0x00000001 > #define RWSEM_WAITING_BIAS (~RWSEM_ACTIVE_MASK) > #define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS > #define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) > > with just that two-line difference for the 32-bit/64-bit case. > > At least I _think_ so. >
Yes, I already had that change in my tree (or rather, I wrote it as (-RWSEM_ACTIVE_MASK-1) to be consistent with what was previously there, but (~RWSEM_ACTIVE_MASK) makes more sense.)
> And it's worth noting (again) that I didn't actually push the > twsem_count_t changes down into the slow-path code in lib/rwsem.c. There's > a few variables there that might need looking at too. I _think_ they are > all ok as-is (unlike the header file, lib/rwsem.c seems to consistently > use 'signed long' rather than mix 32-bit and 64-bit types), but it migh be > cleaner to make them rwsem_count_t's too.
Yes, if we have it we should it consistently.
-hpa
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