On Thu, 18 Feb 2010, Peter Zijlstra wrote: > On Wed, 2010-02-17 at 18:47 +0000, Thomas Gleixner wrote: > > > > xtime_lock needs a raw_spinlock in preempt-rt. Convert it to > > raw_seqlock and fix up all users. > > > s/raw_spinlock/raw_seqlock/ ? > > Maybe add an explanation on _why_ -rt needs this for the uninformed > amongst us. > > -rt switches to sleeping spinlocks, but since the vdso is basically > userspace it cannot schedule, hence we need to keep using actual > spinlocks (this is also the reason the vdso things must not call into > lockdep) No, the read_seq side is not taking the lock. It's just the write side which is taking the spinlock to serialize against other writers. xtime_lock is write locked in the timer interrupt context and therefor cannot take a sleeping spinlock. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
