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rcutorture: Export RCU grace-period kthread wait state to rcutorture

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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: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney 2014-03-12 07:10:41 -07:00
parent 945fa9c631
commit afea227fd4
5 changed files with 30 additions and 1 deletions
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4
include/linux/rcutiny.h
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@ -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)
{
}

1
include/linux/rcutree.h
View File

@ -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);

1
kernel/rcu/rcutorture.c
View File

@ -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;

17
kernel/rcu/tree.c
View File

@ -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) ||

8
kernel/rcu/tree.h
View File

@ -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. */