From afea227fd4acf4f097a9e77bbc2f07d4856ebd01 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 12 Mar 2014 07:10:41 -0700 Subject: [PATCH] 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: Paul E. McKenney Reviewed-by: Josh Triplett --- include/linux/rcutiny.h | 4 ++++ include/linux/rcutree.h | 1 + kernel/rcu/rcutorture.c | 1 + kernel/rcu/tree.c | 17 +++++++++++++++++ kernel/rcu/tree.h | 8 +++++++- 5 files changed, 30 insertions(+), 1 deletion(-) diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 425c659d54e5..d40a6a451330 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -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) { } diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index a59ca05fd4e3..3e2f5d432743 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -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); diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 9decce0f110c..37ae5e1d4a1d 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -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; diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 3d15b5a82ae8..93e64381aa2a 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -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) || diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 75dc3c39a02a..c2fd1e722879 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -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. */ -- 2.34.1