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Commit cdc694b2 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Add kernel parameter to dump trace after RCU CPU stall warning 



This commit adds a rcu_cpu_stall_ftrace_dump kernel boot parameter, that,
when set, causes the trace buffer to be dumped after an RCU CPU stall
warning is printed.  This kernel boot parameter is disabled by default,
maintaining compatibility with previous behavior.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
parent 1f3ebc82

Documentation/admin-guide/kernel-parameters.txt

+4 −0
Original line number Diff line number Diff line
@@ -4047,6 +4047,10 @@ 
	rcutorture.verbose= [KNL]

			Enable additional printk() statements.



	rcupdate.rcu_cpu_stall_ftrace_dump= [KNL]

			Dump ftrace buffer after reporting RCU CPU

			stall warning.



	rcupdate.rcu_cpu_stall_suppress= [KNL]

			Suppress RCU CPU stall warning messages.

kernel/rcu/rcu.h

+1 −0
Original line number Diff line number Diff line
@@ -227,6 +227,7 @@ static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head) 


#ifdef CONFIG_RCU_STALL_COMMON



extern int rcu_cpu_stall_ftrace_dump;

extern int rcu_cpu_stall_suppress;

extern int rcu_cpu_stall_timeout;

int rcu_jiffies_till_stall_check(void);

kernel/rcu/tree_stall.h

+4 −0
Original line number Diff line number Diff line
@@ -527,6 +527,8 @@ static void check_cpu_stall(struct rcu_data *rdp) 


		/* We haven't checked in, so go dump stack. */

		print_cpu_stall();

		if (rcu_cpu_stall_ftrace_dump)

			rcu_ftrace_dump(DUMP_ALL);



	} else if (rcu_gp_in_progress() &&

		   ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY) &&
@@ -534,6 +536,8 @@ static void check_cpu_stall(struct rcu_data *rdp) 


		/* They had a few time units to dump stack, so complain. */

		print_other_cpu_stall(gs2);

		if (rcu_cpu_stall_ftrace_dump)

			rcu_ftrace_dump(DUMP_ALL);

	}

}

kernel/rcu/update.c

+2 −0
Original line number Diff line number Diff line
@@ -437,6 +437,8 @@ EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity); 
#endif



#ifdef CONFIG_RCU_STALL_COMMON

int rcu_cpu_stall_ftrace_dump __read_mostly;

module_param(rcu_cpu_stall_ftrace_dump, int, 0644);

int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */

EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress);

module_param(rcu_cpu_stall_suppress, int, 0644);