Re: [patch 05/44] generic {,test_and_}{set,clear,change}_bit()

[Russell King <rmk+lkml@arm.linux.org.uk>]

On Fri, Feb 03, 2006 at 10:55:36AM +0100, Martin Waitz wrote:
> On Wed, Feb 01, 2006 at 06:02:29PM +0900, Akinobu Mita wrote:
> > +static __inline__ void set_bit(int nr, volatile unsigned long *addr)
> > +{
> > +	unsigned long mask = BITOP_MASK(nr);
> > +	unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
> > +	unsigned long flags;
> > +
> > +	_atomic_spin_lock_irqsave(p, flags);
> > +	*p  |= mask;
> > +	_atomic_spin_unlock_irqrestore(p, flags);
> > +}
> 
> You could even use your new generic non-atomic bitops to implement these

Depends - to do so would increase the amount of code within the
locked region, which raises the probability of contention since the
locked time becomes longer.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/