From 565cfb9e64dac1aadf7e2130fcda19a1c018df66 Mon Sep 17 00:00:00 2001 From: Sangmoon Kim Date: Tue, 2 Mar 2021 20:55:15 +0900 Subject: rcu/tree: Add a trace event for RCU CPU stall warnings This commit adds a trace event which allows tracing the beginnings of RCU CPU stall warnings on systems where sysctl_panic_on_rcu_stall is disabled. The first parameter is the name of RCU flavor like other trace events. The second parameter indicates whether this is a stall of an expedited grace period, a self-detected stall of a normal grace period, or a stall of a normal grace period detected by some CPU other than the one that is stalled. RCU CPU stall warnings are often caused by external-to-RCU issues, for example, in interrupt handling or task scheduling. Therefore, this event uses TRACE_EVENT, not TRACE_EVENT_RCU, to avoid requiring those interested in tracing RCU CPU stalls to rebuild their kernels with CONFIG_RCU_TRACE=y. Reviewed-by: Uladzislau Rezki (Sony) Reviewed-by: Neeraj Upadhyay Signed-off-by: Sangmoon Kim Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_exp.h | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/rcu/tree_exp.h') diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 6c6ff06d4ae6..2796084ef85a 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -521,6 +521,7 @@ static void synchronize_rcu_expedited_wait(void) if (rcu_stall_is_suppressed()) continue; panic_on_rcu_stall(); + trace_rcu_stall_warning(rcu_state.name, TPS("ExpeditedStall")); pr_err("INFO: %s detected expedited stalls on CPUs/tasks: {", rcu_state.name); ndetected = 0; -- cgit v1.2.3