diff mbox

[tip/core/rcu,38/47] lockdep: Add CPU-idle/offline warning to lockdep-RCU splat

Message ID 1328319922-30828-38-git-send-email-paulmck@linux.vnet.ibm.com
State Accepted
Commit c5fdcec927ee31fc96e92339c3a83ac6e0725289
Headers show

Commit Message

Paul E. McKenney Feb. 4, 2012, 1:45 a.m. UTC 
From: "Paul E. McKenney" <paul.mckenney@linaro.org>

It is illegal to use RCU from a CPU that has reported idleness or
offlinedness to RCU.  However, it can be quite difficult to determine
from a stack trace whether or not a given CPU is idle or offline.
Therefore, this commit adds idle/offline diagnostics to the lockdep-RCU
error message.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/lockdep.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
diff mbox

Patch

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 8889f7d..ea9ee45 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -4176,7 +4176,13 @@  void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
 	printk("-------------------------------\n");
 	printk("%s:%d %s!\n", file, line, s);
 	printk("\nother info that might help us debug this:\n\n");
-	printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
+	printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
+	       !rcu_lockdep_current_cpu_online()
+			? "RCU used illegally from offline CPU!\n"
+			: rcu_is_cpu_idle()
+				? "RCU used illegally from idle CPU!\n"
+				: "",
+	       rcu_scheduler_active, debug_locks);
 
 	/*
 	 * If a CPU is in the RCU-free window in idle (ie: in the section