On śro, 2015-02-04 at 05:14 -0800, Paul E. McKenney wrote: > On Wed, Feb 04, 2015 at 01:00:18PM +0000, Russell King - ARM Linux wrote: > > On Wed, Feb 04, 2015 at 12:39:07PM +0100, Krzysztof Kozlowski wrote: > > > +Cc some ARM people > > > > I wish that people would CC this list with problems seen on ARM. I'm > > minded to just ignore this message because of this in the hope that by > > doing so, people will learn something... > > > > > > Another thing I could do would be to have an arch-specific Kconfig > > > > variable that made ARM responsible for informing RCU that the CPU > > > > was departing, which would allow a call to as follows to be placed > > > > immediately after the complete(): > > > > > > > > rcu_cpu_notify(NULL, CPU_DYING_IDLE, (void *)(long)smp_processor_id()); > > > > > > > > Note: This absolutely requires that the rcu_cpu_notify() -always- > > > > be allowed to execute!!! This will not work if there is -any- > > > > possibility > > > > of __cpu_die() powering off the outgoing CPU before the call to > > > > rcu_cpu_notify() returns. > > > > Exactly, so that's not going to be possible. The completion at that > > point marks the point at which power _could_ be removed from the CPU > > going down. > > OK, sounds like a polling loop is required.
I thought about using wait_on_bit() in __cpu_die() (the waiting thread) and clearing the bit on CPU being powered down. What do you think about such idea? Best regards, Krzysztof -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
