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Message-Id: <20240816062532.51893-2-neeraj.upadhyay@kernel.org>
Date: Fri, 16 Aug 2024 11:55:31 +0530
From: neeraj.upadhyay@...nel.org
To: rcu@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
kernel-team@...a.com,
rostedt@...dmis.org,
paulmck@...nel.org,
neeraj.upadhyay@...nel.org,
neeraj.upadhyay@....com,
boqun.feng@...il.com,
joel@...lfernandes.org,
urezki@...il.com,
frederic@...nel.org
Subject: [PATCH rcu 2/3] srcu: Check for concurrent updates of heuristics
From: "Paul E. McKenney" <paulmck@...nel.org>
SRCU maintains the ->srcu_n_exp_nodelay and ->reschedule_count values
to guide heuristics governing auto-expediting of normal SRCU grace
periods and grace-period-state-machine delays. This commit adds KCSAN
ASSERT_EXCLUSIVE_WRITER() calls to check for concurrent updates to
these fields.
Signed-off-by: "Paul E. McKenney" <paulmck@...nel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@...nel.org>
---
kernel/rcu/srcutree.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 6fd9c914ce64..aaee09a6748c 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -629,6 +629,7 @@ static unsigned long srcu_get_delay(struct srcu_struct *ssp)
if (time_after(j, gpstart))
jbase += j - gpstart;
if (!jbase) {
+ ASSERT_EXCLUSIVE_WRITER(sup->srcu_n_exp_nodelay);
WRITE_ONCE(sup->srcu_n_exp_nodelay, READ_ONCE(sup->srcu_n_exp_nodelay) + 1);
if (READ_ONCE(sup->srcu_n_exp_nodelay) > srcu_max_nodelay_phase)
jbase = 1;
@@ -1819,6 +1820,7 @@ static void process_srcu(struct work_struct *work)
} else {
j = jiffies;
if (READ_ONCE(sup->reschedule_jiffies) == j) {
+ ASSERT_EXCLUSIVE_WRITER(sup->reschedule_count);
WRITE_ONCE(sup->reschedule_count, READ_ONCE(sup->reschedule_count) + 1);
if (READ_ONCE(sup->reschedule_count) > srcu_max_nodelay)
curdelay = 1;
--
2.40.1
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