On 7/26/06, s prashant <sprashant16@xxxxxxxxx> wrote:
On 7/26/06, Om. <om.turyx@xxxxxxxxx> wrote:
> On 7/25/06, Grob Team <grobteam@xxxxxxxxx> wrote:
> > On 7/25/06, s prashant <sprashant16@xxxxxxxxx> wrote:
> > > On 7/25/06, Gaurav Dhiman < gauravd.chd@xxxxxxxxx> wrote:
> > >
> > > > May I know where you read this. It does not seems ok to me.
> > > > I agree with your view point.
> > > >
> > > > Gaurav
> > > There are quite a few variants of spin locks.
> > > 1.spin_lock
> > > spin_unlock
> > >
> > > The above ones are used when you know the critical section that
> > > you are protecting will not accessed from an interrupt handler.
> > > In case of uniprocessor m/c these locks are not effective as they
> > > compile away to nothing.
> > >
> > > 2.spin_lock_irqsave
> > > spin_unlock_irqrestore
> > > These locks also disable the interrrupts.
> I agree with you that there are multiple types of spin locks and
<snip>
hi om,
here is a snap shot of spin_lock macro in 2.6 kernel
#define spin_lock(lock) \
do { \
preempt_disable(); \
if (unlikely(!_raw_spin_trylock(lock))) \
__preempt_spin_lock(lock); \
} while (0)
in the above the irq_disable is not called. The local interrupts
I apologize for the wrong comments. What Grob Team replied in his mail
is _correct_.
I overlooked some parts of Documentation/spin_lock.txt. It clearly
states what Grob said in his mail.
Sorry again for any misinformation that I caused to spread.
spin_locks() are used when one is sure that the critical section is
not accessed from an interrupt handler. Otherwise spin_lock_irqsave()
and variants to be used.
Om
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