Prev: Fix possible NULL pointer dereference in print_IO_APIC
Next: [PATCH 1/2] dlm: cleanup remove unused code
From: David Howells on 19 May 2010 10:40
Michel Lespinasse <walken(a)google.com> wrote:

> The basic properties that have been true so far still hold:
> - RWSEM_ACTIVE_READ_BIAS & RWSEM_ACTIVE_MASK == 1
> - RWSEM_ACTIVE_WRITE_BIAS & RWSEM_ACTIVE_MASK == 1
> - RWSEM_WAITING_BIAS & RWSEM_ACTIVE_MASK == 0
> - RWSEM_ACTIVE_WRITE_BIAS < 0 and RWSEM_WAITING_BIAS < 0
>
> A new property is introduced: RWSEM_ACTIVE_WRITE_BIAS is set to be
> 'more negative' than RWSEM_WAITING_BIAS. This way, even the first writer
> will set the rwsem count to be < RWSEM_WAITING_BIAS and down_read_critical()
> can make use of this to determine if there are any active writers.
>
> Signed-off-by: Michel Lespinasse <walken(a)google.com>

Acked-by: David Howells <dhowells(a)redhat.com>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: Fix possible NULL pointer dereference in print_IO_APIC
Next: [PATCH 1/2] dlm: cleanup remove unused code