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Subject[tip: core/rcu] rcutorture: Make rcu_torture_boost_failed() check for GP end
The following commit has been merged into the core/rcu branch of tip:

Commit-ID: bcd4af44e2f173074328980b60178fdbb1853e4f
Gitweb: https://git.kernel.org/tip/bcd4af44e2f173074328980b60178fdbb1853e4f
Author: Paul E. McKenney <paulmck@kernel.org>
AuthorDate: Thu, 08 Apr 2021 10:46:55 -07:00
Committer: Paul E. McKenney <paulmck@kernel.org>
CommitterDate: Mon, 10 May 2021 16:05:06 -07:00

rcutorture: Make rcu_torture_boost_failed() check for GP end

It is possible that a delayed grace period that rcu_torture_boost()
was polling for ended while rcu_torture_boost_failed() was printing the
failure splat. It would be good to know when this happens. This commit
therefore has rcu_torture_boost_failed() recheck the grace period after
printing the splat, and printing a message indicating whether or not
the grace period has ended.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/rcutorture.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 31338b2..02a14df 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -919,6 +919,7 @@ static void rcu_torture_enable_rt_throttle(void)
static bool rcu_torture_boost_failed(unsigned long gp_state, unsigned long start, unsigned long end)
{
static int dbg_done;
+ bool gp_done;

if (end - start > test_boost_duration * HZ - HZ / 2) {
// Recheck after checking time to avoid false positives.
@@ -931,6 +932,11 @@ static bool rcu_torture_boost_failed(unsigned long gp_state, unsigned long start
pr_info("Boost inversion thread ->rt_priority %u gp_state %lu jiffies %lu\n",
current->rt_priority, gp_state, end - start);
cur_ops->gp_kthread_dbg();
+ // Recheck after print to flag grace period ending during splat.
+ gp_done = cur_ops->poll_gp_state(gp_state);
+ pr_info("Boost inversion: GP %lu %s.\n", gp_state,
+ gp_done ? "ended already" : "still pending");
+
}

return true; // failed
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