Re: [x86] Unify semaphore_32.S and rwlock_64.S

From: H. Peter Anvin
Date: Wed Jan 20 2010 - 19:56:38 EST

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
> 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
> 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.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at