rcutorture: Add forward-progress checking for writer
The rcutorture output currently does not distinguish between stalls in the RCU implementation and stalls in the rcu_torture_writer() kthreads. This commit therefore adds some diagnostics to help distinguish between these two conditions, at least for the non-SRCU implementations. (SRCU does not provide evidence of update-side forward progress by design.) Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney
parent
c9eaa447e7
commit
ad0dc7f94d
3 changed files with 89 additions and 0 deletions
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@ -51,7 +51,17 @@ extern int rcu_expedited; /* for sysctl */
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extern int rcutorture_runnable; /* for sysctl */
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#endif /* #ifdef CONFIG_RCU_TORTURE_TEST */
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enum rcutorture_type {
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RCU_FLAVOR,
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RCU_BH_FLAVOR,
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RCU_SCHED_FLAVOR,
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SRCU_FLAVOR,
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INVALID_RCU_FLAVOR
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};
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#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
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void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
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unsigned long *gpnum, unsigned long *completed);
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void rcutorture_record_test_transition(void);
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void rcutorture_record_progress(unsigned long vernum);
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void do_trace_rcu_torture_read(const char *rcutorturename,
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@ -60,6 +70,15 @@ void do_trace_rcu_torture_read(const char *rcutorturename,
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unsigned long c_old,
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unsigned long c);
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#else
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static inline void rcutorture_get_gp_data(enum rcutorture_type test_type,
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int *flags,
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unsigned long *gpnum,
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unsigned long *completed)
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{
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*flags = 0;
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*gpnum = 0;
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*completed = 0;
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}
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static inline void rcutorture_record_test_transition(void)
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{
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}
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@ -138,6 +138,15 @@ static long n_barrier_attempts;
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static long n_barrier_successes;
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static struct list_head rcu_torture_removed;
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static int rcu_torture_writer_state;
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#define RTWS_FIXED_DELAY 0
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#define RTWS_DELAY 1
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#define RTWS_REPLACE 2
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#define RTWS_DEF_FREE 3
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#define RTWS_EXP_SYNC 4
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#define RTWS_STUTTER 5
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#define RTWS_STOPPING 6
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#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
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#define RCUTORTURE_RUNNABLE_INIT 1
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#else
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@ -214,6 +223,7 @@ rcu_torture_free(struct rcu_torture *p)
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*/
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struct rcu_torture_ops {
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int ttype;
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void (*init)(void);
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int (*readlock)(void);
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void (*read_delay)(struct torture_random_state *rrsp);
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@ -312,6 +322,7 @@ static void rcu_sync_torture_init(void)
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}
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static struct rcu_torture_ops rcu_ops = {
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.ttype = RCU_FLAVOR,
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.init = rcu_sync_torture_init,
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.readlock = rcu_torture_read_lock,
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.read_delay = rcu_read_delay,
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@ -355,6 +366,7 @@ static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
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}
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static struct rcu_torture_ops rcu_bh_ops = {
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.ttype = RCU_BH_FLAVOR,
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.init = rcu_sync_torture_init,
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.readlock = rcu_bh_torture_read_lock,
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.read_delay = rcu_read_delay, /* just reuse rcu's version. */
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@ -397,6 +409,7 @@ call_rcu_busted(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
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}
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static struct rcu_torture_ops rcu_busted_ops = {
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.ttype = INVALID_RCU_FLAVOR,
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.init = rcu_sync_torture_init,
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.readlock = rcu_torture_read_lock,
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.read_delay = rcu_read_delay, /* just reuse rcu's version. */
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@ -492,6 +505,7 @@ static void srcu_torture_synchronize_expedited(void)
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}
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static struct rcu_torture_ops srcu_ops = {
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.ttype = SRCU_FLAVOR,
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.init = rcu_sync_torture_init,
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.readlock = srcu_torture_read_lock,
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.read_delay = srcu_read_delay,
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@ -527,6 +541,7 @@ static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
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}
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static struct rcu_torture_ops sched_ops = {
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.ttype = RCU_SCHED_FLAVOR,
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.init = rcu_sync_torture_init,
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.readlock = sched_torture_read_lock,
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.read_delay = rcu_read_delay, /* just reuse rcu's version. */
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@ -699,12 +714,15 @@ rcu_torture_writer(void *arg)
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set_user_nice(current, MAX_NICE);
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do {
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rcu_torture_writer_state = RTWS_FIXED_DELAY;
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schedule_timeout_uninterruptible(1);
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rp = rcu_torture_alloc();
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if (rp == NULL)
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continue;
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rp->rtort_pipe_count = 0;
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rcu_torture_writer_state = RTWS_DELAY;
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udelay(torture_random(&rand) & 0x3ff);
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rcu_torture_writer_state = RTWS_REPLACE;
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old_rp = rcu_dereference_check(rcu_torture_current,
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current == writer_task);
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rp->rtort_mbtest = 1;
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@ -721,8 +739,10 @@ rcu_torture_writer(void *arg)
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else
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exp = gp_exp;
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if (!exp) {
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rcu_torture_writer_state = RTWS_DEF_FREE;
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cur_ops->deferred_free(old_rp);
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} else {
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rcu_torture_writer_state = RTWS_EXP_SYNC;
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cur_ops->exp_sync();
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list_add(&old_rp->rtort_free,
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&rcu_torture_removed);
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@ -743,8 +763,10 @@ rcu_torture_writer(void *arg)
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}
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}
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rcutorture_record_progress(++rcu_torture_current_version);
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rcu_torture_writer_state = RTWS_STUTTER;
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stutter_wait("rcu_torture_writer");
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} while (!torture_must_stop());
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rcu_torture_writer_state = RTWS_STOPPING;
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torture_kthread_stopping("rcu_torture_writer");
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return 0;
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}
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@ -937,6 +959,7 @@ rcu_torture_printk(char *page)
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int i;
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long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
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long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
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static unsigned long rtcv_snap = ULONG_MAX;
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for_each_possible_cpu(cpu) {
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for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
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@ -997,6 +1020,20 @@ rcu_torture_printk(char *page)
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page += sprintf(page, "\n");
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if (cur_ops->stats)
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cur_ops->stats(page);
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if (rtcv_snap == rcu_torture_current_version &&
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rcu_torture_current != NULL) {
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int __maybe_unused flags;
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unsigned long __maybe_unused gpnum;
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unsigned long __maybe_unused completed;
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rcutorture_get_gp_data(cur_ops->ttype,
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&flags, &gpnum, &completed);
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page += sprintf(page,
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"??? Writer stall state %d g%lu c%lu f%#x\n",
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rcu_torture_writer_state,
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gpnum, completed, flags);
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}
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rtcv_snap = rcu_torture_current_version;
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}
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/*
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@ -293,6 +293,39 @@ void rcutorture_record_test_transition(void)
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}
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EXPORT_SYMBOL_GPL(rcutorture_record_test_transition);
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/*
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* Send along grace-period-related data for rcutorture diagnostics.
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*/
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void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
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unsigned long *gpnum, unsigned long *completed)
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{
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struct rcu_state *rsp = NULL;
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switch (test_type) {
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case RCU_FLAVOR:
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rsp = rcu_state;
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break;
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case RCU_BH_FLAVOR:
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rsp = &rcu_bh_state;
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break;
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case RCU_SCHED_FLAVOR:
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rsp = &rcu_sched_state;
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break;
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default:
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break;
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}
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if (rsp != NULL) {
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*flags = ACCESS_ONCE(rsp->gp_flags);
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*gpnum = ACCESS_ONCE(rsp->gpnum);
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*completed = ACCESS_ONCE(rsp->completed);
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return;
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}
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*flags = 0;
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*gpnum = 0;
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*completed = 0;
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}
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EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);
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/*
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* Record the number of writer passes through the current rcutorture test.
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* This is also used to correlate debugfs tracing stats with the rcutorture
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