On Thu, Aug 30, 2012 at 02:05:33PM -0700, Paul E. McKenney wrote: > From: Frederic Weisbecker <fweisbec@xxxxxxxxx> > > In the old times, the whole idle task was considered > as an RCU quiescent state. But as RCU became more and > more successful overtime, some RCU read side critical > section have been added even in the code of some > architectures idle tasks, for tracing for example. > > So nowadays, rcu_idle_enter() and rcu_idle_exit() must > be called by the architecture to tell RCU about the part > in the idle loop that doesn't make use of rcu read side > critical sections, typically the part that puts the CPU > in low power mode. > > This is necessary for RCU to find the quiescent states in > idle in order to complete grace periods. > > Add this missing pair of calls in the Alpha's idle loop. > > Reported-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> > Cc: Richard Henderson <rth@xxxxxxxxxxx> > Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx> > Cc: Matt Turner <mattst88@xxxxxxxxx> > Cc: alpha <linux-alpha@xxxxxxxxxxxxxxx> > Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > Cc: Michael Cree <mcree@xxxxxxxxxxxx> > Cc: 3.2.x.. <stable@xxxxxxxxxxxxxxx> Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx> > arch/alpha/kernel/process.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c > index eac5e01..eb9558c 100644 > --- a/arch/alpha/kernel/process.c > +++ b/arch/alpha/kernel/process.c > @@ -28,6 +28,7 @@ > #include <linux/tty.h> > #include <linux/console.h> > #include <linux/slab.h> > +#include <linux/rcupdate.h> > > #include <asm/reg.h> > #include <asm/uaccess.h> > @@ -54,9 +55,11 @@ cpu_idle(void) > /* FIXME -- EV6 and LCA45 know how to power down > the CPU. */ > > + rcu_idle_enter(); > while (!need_resched()) > cpu_relax(); > > + rcu_idle_exit(); > schedule_preempt_disabled(); > } > } > -- > 1.7.8 > -- To unsubscribe from this list: send the line "unsubscribe linux-alpha" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
