lkml.org 
[lkml]   [2010]   [Jan]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [x86] Unify semaphore_32.S and rwlock_64.S


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.

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.

Linus


\
 
 \ /
  Last update: 2010-01-21 01:49    [W:0.066 / U:0.048 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site