commit 0989cb46783188ea7346ba6490be0046b9b7a725
author Paul E. McKenney <paul.mckenney@linaro.org> Tue Nov 01 08:57:21 2011 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> Sun Dec 11 10:31:42 2011 -0800
tree ab3ca7e6099efd9ca814e9202a679388f36ecc90
parent 4145fa7fbee3ec1e61c52825b146192885d9759f

rcu: Add more information to the wrong-idle-task complaint

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>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

kernel/rcutiny.c

diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index 9b9bdf6..6d70ff7 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -65,10 +65,14 @@
 	}
 	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) */
 }
@@ -115,10 +119,14 @@
 	}
 	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! */
 	}
 }
 

kernel/rcutree.c

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 06e40dd..9888a0a 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -356,10 +356,14 @@
 	}
 	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 @@
 	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! */
 	}
 }