Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH RFC tip/core/rcu 3/3] cpuidle: Inform RCU of read-side critical sections | Date | Thu, 2 Feb 2012 17:12:48 -0800 |
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From: "Paul E. McKenney" <paul.mckenney@linaro.org>
The cpuidle_idle_call() function is invoked in the inner idle loop, after the call to rcu_idle_enter() and before the call to rcu_idle_exit(). This means that RCU is ignoring the CPU at this point. Unfortunately, cpuidle_idle_call() nevertheless contains tracepoints (important ones used by powertop) that expect RCU to be paying attention. The consequences of using RCU read-side critical sections on CPUs that RCU is ignoring can be severe, including random corruption of random memory.
Therefore, this commit uses the new RCU_NONIDLE() macro to let RCU do its job with respect to the tracepoints.
Suggested-by: Nicolas Pitre <nicolas.pitre@linaro.org> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Kevin Hilman <khilman@ti.com> Cc: Len Brown <len.brown@intel.com> Cc: Trinabh Gupta <g.trinabh@gmail.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Deepthi Dharwar <deepthi@linux.vnet.ibm.com> --- drivers/cpuidle/cpuidle.c | 12 ++++++++---- 1 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 59f4261..cd8a553 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -94,13 +94,17 @@ int cpuidle_idle_call(void) target_state = &drv->states[next_state]; - trace_power_start(POWER_CSTATE, next_state, dev->cpu); - trace_cpu_idle(next_state, dev->cpu); + RCU_NONIDLE( + trace_power_start(POWER_CSTATE, next_state, dev->cpu); + trace_cpu_idle(next_state, dev->cpu) + ); entered_state = target_state->enter(dev, drv, next_state); - trace_power_end(dev->cpu); - trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu); + RCU_NONIDLE( + trace_power_end(dev->cpu); + trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu); + ); if (entered_state >= 0) { /* Update cpuidle counters */ -- 1.7.8
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