[PATCH rcu v2] 06/11] rcutorture: Add ftrace-compatible timestamp to GP# failure/close-call output

[Paul E. McKenney]

This commit adds an ftrace-compatible microsecond-scale timestamp
to the failure/close-call output, but only in kernels built with
CONFIG_RCU_TORTURE_TEST_LOG_GP=y.

Signed-off-by: Paul E. McKenney <paul...@kernel.org>
---
 kernel/rcu/rcutorture.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 5b0510c79fde..0f5a94542719 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -275,6 +275,7 @@ struct rt_read_seg {
        int rt_end_cpu;
        unsigned long long rt_gp_seq;
        unsigned long long rt_gp_seq_end;
+       u64 rt_ts;
 };
 static int err_segs_recorded;
 static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
@@ -2000,6 +2001,7 @@ static void rcutorture_one_extend(int *readstate, int 
newstate, bool insoftirq,
        // Sample grace-period sequence number, as good a place as any.
        if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_LOG_GP) && 
cur_ops->gather_gp_seqs) {
                rtrsp->rt_gp_seq = cur_ops->gather_gp_seqs();
+               rtrsp->rt_ts = ktime_get_mono_fast_ns();
                if (!first)
                        rtrsp[-1].rt_gp_seq_end = rtrsp->rt_gp_seq;
        }
@@ -3674,7 +3676,11 @@ rcu_torture_cleanup(void)
                        pr_alert("\t: No segments recorded!!!\n");
                firsttime = 1;
                for (i = 0; i < rt_read_nsegs; i++) {
-                       pr_alert("\t%d: %#4x", i, err_segs[i].rt_readstate);
+                       if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_LOG_GP))
+                               pr_alert("\t%lluus ", 
div64_u64(err_segs[i].rt_ts, 1000ULL));
+                       else
+                               pr_alert("\t");
+                       pr_cont("%d: %#4x", i, err_segs[i].rt_readstate);
                        if (err_segs[i].rt_delay_jiffies != 0) {
                                pr_cont("%s%ldjiffies", firsttime ? "" : "+",
                                        err_segs[i].rt_delay_jiffies);
-- 
2.40.1