From 6231069bdab575fce862ca786f1c0ba5e4e9ba3b Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 6 Mar 2013 13:37:09 -0800 Subject: rcu: Add softirq-stall indications to stall-warning messages If RCU's softirq handler is prevented from executing, an RCU CPU stall warning can result. Ways to prevent RCU's softirq handler from executing include: (1) CPU spinning with interrupts disabled, (2) infinite loop in some softirq handler, and (3) in -rt kernels, an infinite loop in a set of real-time threads running at priorities higher than that of RCU's softirq handler. Because this situation can be difficult to track down, this commit causes the count of RCU softirq handler invocations to be printed with RCU CPU stall warnings. This information does require some interpretation, as now documented in Documentation/RCU/stallwarn.txt. Reported-by: Thomas Gleixner Signed-off-by: Paul E. McKenney Tested-by: Paul Gortmaker --- kernel/rcutree.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'kernel/rcutree.h') diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 8e756099a1a..26c9bb3166a 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -325,6 +325,11 @@ struct rcu_data { struct task_struct *nocb_kthread; #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ + /* 8) RCU CPU stall data. */ +#ifdef CONFIG_RCU_CPU_STALL_INFO + unsigned int softirq_snap; /* Snapshot of softirq activity. */ +#endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ + int cpu; struct rcu_state *rsp; }; -- cgit v1.2.3-18-g5258