From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH rcu 4/7] locktorture: Mark statistics data races
Date: Wed, 21 Jul 2021 14:04:38 -0700 [thread overview]
Message-ID: <20210721210441.796995-4-paulmck@kernel.org> (raw)
In-Reply-To: <20210721210421.GA788053@paulmck-ThinkPad-P17-Gen-1>
The lock_stress_stats structure's ->n_lock_fail and ->n_lock_acquired
fields are incremented and sampled locklessly using plain C-language
statements, which KCSAN objects to. This commit therefore marks the
statistics gathering with data_race() to flag the intent. While in
the area, this commit also reduces the number of accesses to the
->n_lock_acquired field, thus eliminating some possible check/use
confusion.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/locking/locktorture.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index b3adb40549bf3..313d5e613fbe6 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -738,20 +738,22 @@ static int lock_torture_reader(void *arg)
static void __torture_print_stats(char *page,
struct lock_stress_stats *statp, bool write)
{
+ long cur;
bool fail = false;
int i, n_stress;
- long max = 0, min = statp ? statp[0].n_lock_acquired : 0;
+ long max = 0, min = statp ? data_race(statp[0].n_lock_acquired) : 0;
long long sum = 0;
n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress;
for (i = 0; i < n_stress; i++) {
- if (statp[i].n_lock_fail)
+ if (data_race(statp[i].n_lock_fail))
fail = true;
- sum += statp[i].n_lock_acquired;
- if (max < statp[i].n_lock_acquired)
- max = statp[i].n_lock_acquired;
- if (min > statp[i].n_lock_acquired)
- min = statp[i].n_lock_acquired;
+ cur = data_race(statp[i].n_lock_acquired);
+ sum += cur;
+ if (max < cur)
+ max = cur;
+ if (min > cur)
+ min = cur;
}
page += sprintf(page,
"%s: Total: %lld Max/Min: %ld/%ld %s Fail: %d %s\n",
--
2.31.1.189.g2e36527f23
next prev parent reply other threads:[~2021-07-21 21:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-21 21:04 [PATCH rcu 0/7] Torture-test updates for v5.15 Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 1/7] refscale: Add measurement of clock readout Paul E. McKenney
2021-07-28 17:38 ` [PATCH v2 " Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 2/7] rcutorture: Preempt rather than block when testing task stalls Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 3/7] rcuscale: Console output claims too few grace periods Paul E. McKenney
2021-07-21 21:04 ` Paul E. McKenney [this message]
2021-07-21 21:04 ` [PATCH rcu 5/7] locktorture: Count lock readers Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 6/7] scftorture: Add RPC-like IPI tests Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 7/7] scftorture: Avoid NULL pointer exception on early exit Paul E. McKenney
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