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Commit afea227f authored by Paul E. McKenney's avatar Paul E. McKenney
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rcutorture: Export RCU grace-period kthread wait state to rcutorture 



This commit allows rcutorture to print additional state for the
RCU grace-period kthreads in cases where RCU seems reluctant to
start a new grace period.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 945fa9c6

include/linux/rcutiny.h

+4 −0
Original line number Diff line number Diff line
@@ -119,6 +119,10 @@ static inline void rcu_sched_force_quiescent_state(void) 
{

}



static inline void show_rcu_gp_kthreads(void)

{

}



static inline void rcu_cpu_stall_reset(void)

{

}

include/linux/rcutree.h

+1 −0
Original line number Diff line number Diff line
@@ -84,6 +84,7 @@ extern unsigned long rcutorture_vernum; 
long rcu_batches_completed(void);

long rcu_batches_completed_bh(void);

long rcu_batches_completed_sched(void);

void show_rcu_gp_kthreads(void);



void rcu_force_quiescent_state(void);

void rcu_bh_force_quiescent_state(void);

kernel/rcu/rcutorture.c

+1 −0
Original line number Diff line number Diff line
@@ -1034,6 +1034,7 @@ rcu_torture_printk(char *page) 
				"??? Writer stall state %d g%lu c%lu f%#x\n",

				rcu_torture_writer_state,

				gpnum, completed, flags);

		show_rcu_gp_kthreads();

		rcutorture_trace_dump();

	}

	rtcv_snap = rcu_torture_current_version;

kernel/rcu/tree.c

+17 −0
Original line number Diff line number Diff line
@@ -279,6 +279,21 @@ void rcu_bh_force_quiescent_state(void) 
}

EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);



/*

 * Show the state of the grace-period kthreads.

 */

void show_rcu_gp_kthreads(void)

{

	struct rcu_state *rsp;



	for_each_rcu_flavor(rsp) {

		pr_info("%s: wait state: %d ->state: %#lx\n",

			rsp->name, rsp->gp_state, rsp->gp_kthread->state);

		/* sched_show_task(rsp->gp_kthread); */

	}

}

EXPORT_SYMBOL_GPL(show_rcu_gp_kthreads);



/*

 * Record the number of times rcutorture tests have been initiated and

 * terminated.  This information allows the debugfs tracing stats to be
@@ -1626,6 +1641,7 @@ static int __noreturn rcu_gp_kthread(void *arg) 
			trace_rcu_grace_period(rsp->name,

					       ACCESS_ONCE(rsp->gpnum),

					       TPS("reqwait"));

			rsp->gp_state = RCU_GP_WAIT_GPS;

			wait_event_interruptible(rsp->gp_wq,

						 ACCESS_ONCE(rsp->gp_flags) &

						 RCU_GP_FLAG_INIT);
@@ -1653,6 +1669,7 @@ static int __noreturn rcu_gp_kthread(void *arg) 
			trace_rcu_grace_period(rsp->name,

					       ACCESS_ONCE(rsp->gpnum),

					       TPS("fqswait"));

			rsp->gp_state = RCU_GP_WAIT_FQS;

			ret = wait_event_interruptible_timeout(rsp->gp_wq,

					((gf = ACCESS_ONCE(rsp->gp_flags)) &

					 RCU_GP_FLAG_FQS) ||

kernel/rcu/tree.h

+7 −1
Original line number Diff line number Diff line
@@ -406,7 +406,8 @@ struct rcu_state { 
	unsigned long completed;		/* # of last completed gp. */

	struct task_struct *gp_kthread;		/* Task for grace periods. */

	wait_queue_head_t gp_wq;		/* Where GP task waits. */

	int gp_flags;				/* Commands for GP task. */

	short gp_flags;				/* Commands for GP task. */

	short gp_state;				/* GP kthread sleep state. */



	/* End of fields guarded by root rcu_node's lock. */
@@ -469,6 +470,11 @@ struct rcu_state { 
#define RCU_GP_FLAG_INIT 0x1	/* Need grace-period initialization. */

#define RCU_GP_FLAG_FQS  0x2	/* Need grace-period quiescent-state forcing. */



/* Values for rcu_state structure's gp_flags field. */

#define RCU_GP_WAIT_INIT 0	/* Initial state. */

#define RCU_GP_WAIT_GPS  1	/* Wait for grace-period start. */

#define RCU_GP_WAIT_FQS  2	/* Wait for force-quiescent-state time. */



extern struct list_head rcu_struct_flavors;



/* Sequence through rcu_state structures for each RCU flavor. */