rcu: add boot parameter to suppress RCU CPU stall warning messages (742734ee) · Commits · 戴 / test

Although the RCU CPU stall warning messages are a very good way to alert people to a problem, once alerted, it is sometimes helpful to shut them off in order to avoid obscuring other messages that might be being used to track down the problem. Although you can rebuild the kernel with CONFIG_RCU_CPU_STALL_DETECTOR=n, this is sometimes inconvenient. This commit therefore adds a boot parameter named "rcu_cpu_stall_suppress" that shuts these messages off without requiring a rebuild (though a reboot might be needed for those not brave enough to patch their kernel while it is running). This message-suppression was already in place for the panic case, so this commit need only rename the variable and export it via module_param(). Signed-off-by:

Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcutree.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -143,6 +143,11 @@ module_param(blimit, int, 0);
		module_param(qhimark, int, 0);
		module_param(qlowmark, int, 0);

		#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
		int rcu_cpu_stall_suppress __read_mostly;
		module_param(rcu_cpu_stall_suppress, int, 0);
		#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */

		static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
		static int rcu_pending(int cpu);

		@@ -450,7 +455,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)

		#ifdef CONFIG_RCU_CPU_STALL_DETECTOR

		int rcu_cpu_stall_panicking __read_mostly;
		int rcu_cpu_stall_suppress __read_mostly;

		static void record_gp_stall_check_time(struct rcu_state *rsp)
		{
		@@ -530,7 +535,7 @@ static void check_cpu_stall(struct rcu_state rsp, struct rcu_data rdp)
		long delta;
		struct rcu_node *rnp;

		if (rcu_cpu_stall_panicking)
		if (rcu_cpu_stall_suppress)
		return;
		delta = jiffies - rsp->jiffies_stall;
		rnp = rdp->mynode;
		@@ -548,7 +553,7 @@ static void check_cpu_stall(struct rcu_state rsp, struct rcu_data rdp)

		static int rcu_panic(struct notifier_block this, unsigned long ev, void ptr)
		{
		rcu_cpu_stall_panicking = 1;
		rcu_cpu_stall_suppress = 1;
		return NOTIFY_DONE;
		}

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