Re: [PATCH 1/2] locking/rwsem: Add CONFIG_RWSEM_SPIN_ON_OWNER

Davidlohr Bueso
2014-06-06T18:12:44Z

On Fri, 2014-06-06 at 10:13 -0700, Jason Low wrote:
> On Fri, 2014-06-06 at 08:55 -0700, Davidlohr Bueso wrote:
> > Just like with mutexes (CONFIG_MUTEX_SPIN_ON_OWNER),
> > encapsulate the dependencies for rwsem optimistic spinning.
> > No logical changes here as it continues to depend on both
> > SMP and the XADD algorithm variant.
> >
> > Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
> > ---
> > include/linux/rwsem.h | 4 ++--
> > kernel/Kconfig.locks | 4 ++++
> > kernel/locking/rwsem.c | 2 +-
> > 3 files changed, 7 insertions(+), 3 deletions(-)
>
> Do we also want to add an #ifdef CONFIG_RWSEM_SPIN_ON_OWNER in
> __init_rwsem() and in the optimistic spinning functions for rwsem-xadd?
>

Not really, as we conditionally build rwsem-xadd.o based on
CONFIG_RWSEM_XCHGADD_ALGORITHM:

obj-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
obj-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem-xadd.o

So leaving just SMP is ok there.

>
> Besides that:
>
> Acked-by: Jason Low <jason.low2@hp.com>
>

Thanks,
Davidlohr