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authorPaul E. McKenney <paul.mckenney@linaro.org>2011-11-02 07:38:25 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-12-11 10:31:44 -0800
commit11dbaa8cb79a6e4a234a134898436f717a663f01 (patch)
tree79d18cd1af72016fcc54768388e46253208abe2e
parentaea1b35e29e658d42d7ba2237f3aa7f93e18509d (diff)
rcu: Fix idle-task checks
RCU has traditionally relied on idle_cpu() to determine whether a given CPU is running in the context of an idle task, but commit 908a3283 (Fix idle_cpu()) has invalidated this approach. After commit 908a3283, idle_cpu() will return true if the current CPU is currently running the idle task, and will be doing so for the foreseeable future. RCU instead needs to know whether or not the current CPU is currently running the idle task, regardless of what the near future might bring. This commit therefore switches from idle_cpu() to "current->pid != 0". Reported-by: Wu Fengguang <fengguang.wu@intel.com> Suggested-by: Carsten Emde <C.Emde@osadl.org> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Tested-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
-rw-r--r--kernel/rcutiny.c4
-rw-r--r--kernel/rcutree.c4
2 files changed, 4 insertions, 4 deletions
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index 6d70ff71a87..4e16ce36fa0 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -64,7 +64,7 @@ static void rcu_idle_enter_common(long long oldval)
return;
}
RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting));
- if (!idle_cpu(smp_processor_id())) {
+ if (current->pid != 0) {
struct task_struct *idle = idle_task(smp_processor_id());
RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task",
@@ -118,7 +118,7 @@ static void rcu_idle_exit_common(long long oldval)
return;
}
RCU_TRACE(trace_rcu_dyntick("End", oldval, rcu_dynticks_nesting));
- if (!idle_cpu(smp_processor_id())) {
+ if (current->pid != 0) {
struct task_struct *idle = idle_task(smp_processor_id());
RCU_TRACE(trace_rcu_dyntick("Error on exit: not idle task",
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index b1711c48a7e..49e0783fb20 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -355,7 +355,7 @@ static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval)
return;
}
trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting);
- if (!idle_cpu(smp_processor_id())) {
+ if (current->pid != 0) {
struct task_struct *idle = idle_task(smp_processor_id());
trace_rcu_dyntick("Error on entry: not idle task",
@@ -449,7 +449,7 @@ static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval)
smp_mb__after_atomic_inc(); /* See above. */
WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
trace_rcu_dyntick("End", oldval, rdtp->dynticks_nesting);
- if (!idle_cpu(smp_processor_id())) {
+ if (current->pid != 0) {
struct task_struct *idle = idle_task(smp_processor_id());
trace_rcu_dyntick("Error on exit: not idle task",