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Date: Sun, 11 Nov 2018 12:20:17 -0800
From: "Paul E. McKenney" <paulmck@...ux.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
"Paul E. McKenney" <paulmck@...ux.ibm.com>
Subject: [PATCH tip/core/rcu 07/17] rcutorture: Prepare for asynchronous access to rcu_fwd_startat
Because rcutorture's forward-progress checking will trigger from an
OOM notifier, this notifier will introduce asynchronous concurrent
access to the rcu_fwd_startat variable. This commit therefore prepares
for this by converting updates to WRITE_ONCE().
Signed-off-by: Paul E. McKenney <paulmck@...ux.ibm.com>
---
kernel/rcu/rcutorture.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 36a3bc42782d..c4fd61dccedb 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1679,7 +1679,7 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
sd = cur_ops->stall_dur() + 1;
sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
dur = sd4 + torture_random(&trs) % (sd - sd4);
- rcu_fwd_startat = jiffies;
+ WRITE_ONCE(rcu_fwd_startat, jiffies);
stopat = rcu_fwd_startat + dur;
while (time_before(jiffies, stopat) && !torture_must_stop()) {
idx = cur_ops->readlock();
@@ -1728,7 +1728,7 @@ static void rcu_torture_fwd_prog_cr(void)
/* Loop continuously posting RCU callbacks. */
WRITE_ONCE(rcu_fwd_cb_nodelay, true);
cur_ops->sync(); /* Later readers see above write. */
- rcu_fwd_startat = jiffies;
+ WRITE_ONCE(rcu_fwd_startat, jiffies);
stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
n_launders = 0;
n_launders_cb = 0;
--
2.17.1
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