* [PATCH tip/core/rcu 21/26] m68k: Add missing RCU idle APIs on idle loop [not found] ` <1346360743-3628-1-git-send-email-paulmck@linux.vnet.ibm.com> @ 2012-08-30 21:05 ` Paul E. McKenney [not found] ` <1346360743-3628-21-git-send-email-paulmck@linux.vnet.ibm.com> 1 sibling, 0 replies; 2+ messages in thread From: Paul E. McKenney @ 2012-08-30 21:05 UTC (permalink / raw) To: linux-kernel Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, niv, tglx, peterz, rostedt, Valdis.Kletnieks, dhowells, eric.dumazet, darren, fweisbec, sbw, patches, m68k, 3.2.x.., Paul E. McKenney From: Frederic Weisbecker <fweisbec@gmail.com> 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 m68k's idle loop. Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: m68k <linux-m68k@lists.linux-m68k.org> Cc: 3.2.x.. <stable@vger.kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> --- arch/m68k/kernel/process.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c index c488e3c..ac2892e 100644 --- a/arch/m68k/kernel/process.c +++ b/arch/m68k/kernel/process.c @@ -25,6 +25,7 @@ #include <linux/reboot.h> #include <linux/init_task.h> #include <linux/mqueue.h> +#include <linux/rcupdate.h> #include <asm/uaccess.h> #include <asm/traps.h> @@ -75,8 +76,10 @@ void cpu_idle(void) { /* endless idle loop with no priority at all */ while (1) { + rcu_idle_enter(); while (!need_resched()) idle(); + rcu_idle_exit(); schedule_preempt_disabled(); } } -- 1.7.8 ^ permalink raw reply related [flat|nested] 2+ messages in thread
[parent not found: <1346360743-3628-21-git-send-email-paulmck@linux.vnet.ibm.com>]
* Re: [PATCH tip/core/rcu 21/26] m68k: Add missing RCU idle APIs on idle loop [not found] ` <1346360743-3628-21-git-send-email-paulmck@linux.vnet.ibm.com> @ 2012-09-01 0:02 ` Josh Triplett 0 siblings, 0 replies; 2+ messages in thread From: Josh Triplett @ 2012-09-01 0:02 UTC (permalink / raw) To: Paul E. McKenney Cc: linux-kernel, mingo, laijs, dipankar, akpm, mathieu.desnoyers, niv, tglx, peterz, rostedt, Valdis.Kletnieks, dhowells, eric.dumazet, darren, fweisbec, sbw, patches, m68k, 3.2.x.. On Thu, Aug 30, 2012 at 02:05:38PM -0700, Paul E. McKenney wrote: > From: Frederic Weisbecker <fweisbec@gmail.com> > > 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 m68k's idle loop. > > Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> > Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> > Cc: m68k <linux-m68k@lists.linux-m68k.org> > Cc: 3.2.x.. <stable@vger.kernel.org> > Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> > arch/m68k/kernel/process.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c > index c488e3c..ac2892e 100644 > --- a/arch/m68k/kernel/process.c > +++ b/arch/m68k/kernel/process.c > @@ -25,6 +25,7 @@ > #include <linux/reboot.h> > #include <linux/init_task.h> > #include <linux/mqueue.h> > +#include <linux/rcupdate.h> > > #include <asm/uaccess.h> > #include <asm/traps.h> > @@ -75,8 +76,10 @@ void cpu_idle(void) > { > /* endless idle loop with no priority at all */ > while (1) { > + rcu_idle_enter(); > while (!need_resched()) > idle(); > + rcu_idle_exit(); > schedule_preempt_disabled(); > } > } > -- > 1.7.8 > ^ permalink raw reply [flat|nested] 2+ messages in thread
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[not found] ` <1346360743-3628-1-git-send-email-paulmck@linux.vnet.ibm.com>
2012-08-30 21:05 ` [PATCH tip/core/rcu 21/26] m68k: Add missing RCU idle APIs on idle loop Paul E. McKenney
[not found] ` <1346360743-3628-21-git-send-email-paulmck@linux.vnet.ibm.com>
2012-09-01 0:02 ` Josh Triplett
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