| From 0ee23fda59740767324b4340247ca41a2f498ca6 Mon Sep 17 00:00:00 2001 |
| From: Frederic Weisbecker <fweisbec@gmail.com> |
| Date: Wed, 22 Aug 2012 17:27:34 +0200 |
| Subject: score: Add missing RCU idle APIs on idle loop |
| |
| From: Frederic Weisbecker <fweisbec@gmail.com> |
| |
| commit 0ee23fda59740767324b4340247ca41a2f498ca6 upstream. |
| |
| 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 scores's idle loop. |
| |
| Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> |
| Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> |
| Cc: Chen Liqin <liqin.chen@sunplusct.com> |
| Cc: Lennox Wu <lennox.wu@gmail.com> |
| Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> |
| Reviewed-by: Josh Triplett <josh@joshtriplett.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/score/kernel/process.c | 4 +++- |
| 1 file changed, 3 insertions(+), 1 deletion(-) |
| |
| --- a/arch/score/kernel/process.c |
| +++ b/arch/score/kernel/process.c |
| @@ -27,6 +27,7 @@ |
| #include <linux/reboot.h> |
| #include <linux/elfcore.h> |
| #include <linux/pm.h> |
| +#include <linux/rcupdate.h> |
| |
| void (*pm_power_off)(void); |
| EXPORT_SYMBOL(pm_power_off); |
| @@ -50,9 +51,10 @@ void __noreturn cpu_idle(void) |
| { |
| /* endless idle loop with no priority at all */ |
| while (1) { |
| + rcu_idle_enter(); |
| while (!need_resched()) |
| barrier(); |
| - |
| + rcu_idle_exit(); |
| schedule_preempt_disabled(); |
| } |
| } |