| From | "Paul E. McKenney" <> | Subject | [PATCH RFC tip/core/rcu 37/41] lockdep: Add CPU-idle/offline warning to lockdep-RCU splat | Date | Wed, 1 Feb 2012 11:41:55 -0800 |
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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 --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 -- 1.7.8
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