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Subject[PATCH RFC tip/core/rcu 26/28] rcu: Add more information to the wrong-idle-task complaint
Date
From: Paul E. McKenney <paul.mckenney@linaro.org>

The current code just complains if the current task is not the idle task.
This commit therefore adds printing of the identity of the idle task.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcutiny.c | 12 ++++++++++--
kernel/rcutree.c | 12 ++++++++++--
2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index e0df33f..f4e7bc3 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -66,10 +66,14 @@ static void rcu_idle_enter_common(long long oldval)
}
RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting));
if (!idle_cpu(smp_processor_id())) {
- WARN_ON_ONCE(1); /* must be idle task! */
+ struct task_struct *idle = idle_task(smp_processor_id());
+
RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task",
oldval, rcu_dynticks_nesting));
ftrace_dump(DUMP_ALL);
+ WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
+ current->pid, current->comm,
+ idle->pid, idle->comm); /* must be idle task! */
}
rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */
}
@@ -116,10 +120,14 @@ static void rcu_idle_exit_common(long long oldval)
}
RCU_TRACE(trace_rcu_dyntick("End", oldval, rcu_dynticks_nesting));
if (!idle_cpu(smp_processor_id())) {
- WARN_ON_ONCE(1); /* must be idle task! */
+ struct task_struct *idle = idle_task(smp_processor_id());
+
RCU_TRACE(trace_rcu_dyntick("Error on exit: not idle task",
oldval, rcu_dynticks_nesting));
ftrace_dump(DUMP_ALL);
+ WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
+ current->pid, current->comm,
+ idle->pid, idle->comm); /* must be idle task! */
}
}

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index cc04876..2a8d9a6 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -356,10 +356,14 @@ static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval)
}
trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting);
if (!idle_cpu(smp_processor_id())) {
- WARN_ON_ONCE(1); /* must be idle task! */
+ struct task_struct *idle = idle_task(smp_processor_id());
+
trace_rcu_dyntick("Error on entry: not idle task",
oldval, rdtp->dynticks_nesting);
ftrace_dump(DUMP_ALL);
+ WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
+ current->pid, current->comm,
+ idle->pid, idle->comm); /* must be idle task! */
}
/* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
smp_mb__before_atomic_inc(); /* See above. */
@@ -445,10 +449,14 @@ static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval)
WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
trace_rcu_dyntick("End", oldval, rdtp->dynticks_nesting);
if (!idle_cpu(smp_processor_id())) {
- WARN_ON_ONCE(1); /* must be idle task! */
+ struct task_struct *idle = idle_task(smp_processor_id());
+
trace_rcu_dyntick("Error on exit: not idle task",
oldval, rdtp->dynticks_nesting);
ftrace_dump(DUMP_ALL);
+ WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
+ current->pid, current->comm,
+ idle->pid, idle->comm); /* must be idle task! */
}
}

--
1.7.3.2


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