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Message-Id: <20230317031339.10277-6-boqun.feng@gmail.com>
Date: Thu, 16 Mar 2023 20:13:37 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: rcu@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
Waiman Long <longman@...hat.com>,
Boqun Feng <boqun.feng@...il.com>,
Lai Jiangshan <jiangshanlai@...il.com>,
"Paul E. McKenney" <paulmck@...nel.org>,
Josh Triplett <josh@...htriplett.org>,
Steven Rostedt <rostedt@...dmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Davidlohr Bueso <dave@...olabs.net>,
Frederic Weisbecker <frederic@...nel.org>,
Neeraj Upadhyay <quic_neeraju@...cinc.com>,
Joel Fernandes <joel@...lfernandes.org>,
Shuah Khan <shuah@...nel.org>,
David Woodhouse <dwmw2@...radead.org>,
Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
seanjc@...gle.com, linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org
Subject: [PATCH rcu 5/7] rcutorture: Add SRCU deadlock scenarios
From: "Paul E. McKenney" <paulmck@...nel.org>
In order to test the new SRCU-lockdep functionality, this commit adds
an rcutorture.test_srcu_lockdep module parameter that, when non-zero,
selects an SRCU deadlock scenario to execute. This parameter is a
five-digit number formatted as DNNL, where "D" is 1 to force a deadlock
and 0 to avoid doing so; "NN" is the test number, 0 for SRCU-based, 1
for SRCU/mutex-based, and 2 for SRCU/rwsem-based; and "L" is the number
of steps in the deadlock cycle.
Note that rcutorture.test_srcu_lockdep=1 will also force a hard hang.
If a non-zero value of rcutorture.test_srcu_lockdep does not select a
deadlock scenario, a console message is printed and testing continues.
[ paulmck: Apply kernel test robot feedback, add rwsem support. ]
[ paulmck: Apply Dan Carpenter feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
Signed-off-by: Boqun Feng <boqun.feng@...il.com>
---
kernel/rcu/rcutorture.c | 151 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 151 insertions(+)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 8e6c023212cb..80ff9a743d31 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -120,6 +120,7 @@ torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
torture_param(int, test_boost_duration, 4, "Duration of each boost test, seconds.");
torture_param(int, test_boost_interval, 7, "Interval between boost tests, seconds.");
torture_param(bool, test_no_idle_hz, true, "Test support for tickless idle CPUs");
+torture_param(int, test_srcu_lockdep, 0, "Test specified SRCU deadlock scenario.");
torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
static char *torture_type = "rcu";
@@ -3463,6 +3464,154 @@ static void rcutorture_sync(void)
cur_ops->sync();
}
+static DEFINE_MUTEX(mut0);
+static DEFINE_MUTEX(mut1);
+static DEFINE_MUTEX(mut2);
+static DEFINE_MUTEX(mut3);
+static DEFINE_MUTEX(mut4);
+static DEFINE_MUTEX(mut5);
+static DEFINE_MUTEX(mut6);
+static DEFINE_MUTEX(mut7);
+static DEFINE_MUTEX(mut8);
+static DEFINE_MUTEX(mut9);
+
+static DECLARE_RWSEM(rwsem0);
+static DECLARE_RWSEM(rwsem1);
+static DECLARE_RWSEM(rwsem2);
+static DECLARE_RWSEM(rwsem3);
+static DECLARE_RWSEM(rwsem4);
+static DECLARE_RWSEM(rwsem5);
+static DECLARE_RWSEM(rwsem6);
+static DECLARE_RWSEM(rwsem7);
+static DECLARE_RWSEM(rwsem8);
+static DECLARE_RWSEM(rwsem9);
+
+DEFINE_STATIC_SRCU(srcu0);
+DEFINE_STATIC_SRCU(srcu1);
+DEFINE_STATIC_SRCU(srcu2);
+DEFINE_STATIC_SRCU(srcu3);
+DEFINE_STATIC_SRCU(srcu4);
+DEFINE_STATIC_SRCU(srcu5);
+DEFINE_STATIC_SRCU(srcu6);
+DEFINE_STATIC_SRCU(srcu7);
+DEFINE_STATIC_SRCU(srcu8);
+DEFINE_STATIC_SRCU(srcu9);
+
+static int srcu_lockdep_next(const char *f, const char *fl, const char *fs, const char *fu, int i,
+ int cyclelen, int deadlock)
+{
+ int j = i + 1;
+
+ if (j >= cyclelen)
+ j = deadlock ? 0 : -1;
+ if (j >= 0)
+ pr_info("%s: %s(%d), %s(%d), %s(%d)\n", f, fl, i, fs, j, fu, i);
+ else
+ pr_info("%s: %s(%d), %s(%d)\n", f, fl, i, fu, i);
+ return j;
+}
+
+// Test lockdep on SRCU-based deadlock scenarios.
+static void rcu_torture_init_srcu_lockdep(void)
+{
+ int cyclelen;
+ int deadlock;
+ bool err = false;
+ int i;
+ int j;
+ int idx;
+ struct mutex *muts[] = { &mut0, &mut1, &mut2, &mut3, &mut4,
+ &mut5, &mut6, &mut7, &mut8, &mut9 };
+ struct rw_semaphore *rwsems[] = { &rwsem0, &rwsem1, &rwsem2, &rwsem3, &rwsem4,
+ &rwsem5, &rwsem6, &rwsem7, &rwsem8, &rwsem9 };
+ struct srcu_struct *srcus[] = { &srcu0, &srcu1, &srcu2, &srcu3, &srcu4,
+ &srcu5, &srcu6, &srcu7, &srcu8, &srcu9 };
+ int testtype;
+
+ if (!test_srcu_lockdep)
+ return;
+
+ deadlock = test_srcu_lockdep / 1000;
+ testtype = (test_srcu_lockdep / 10) % 100;
+ cyclelen = test_srcu_lockdep % 10;
+ WARN_ON_ONCE(ARRAY_SIZE(muts) != ARRAY_SIZE(srcus));
+ if (WARN_ONCE(deadlock != !!deadlock,
+ "%s: test_srcu_lockdep=%d and deadlock digit %d must be zero or one.\n",
+ __func__, test_srcu_lockdep, deadlock))
+ err = true;
+ if (WARN_ONCE(cyclelen <= 0,
+ "%s: test_srcu_lockdep=%d and cycle-length digit %d must be greater than zero.\n",
+ __func__, test_srcu_lockdep, cyclelen))
+ err = true;
+ if (err)
+ goto err_out;
+
+ if (testtype == 0) {
+ pr_info("%s: test_srcu_lockdep = %05d: SRCU %d-way %sdeadlock.\n",
+ __func__, test_srcu_lockdep, cyclelen, deadlock ? "" : "non-");
+ if (deadlock && cyclelen == 1)
+ pr_info("%s: Expect hang.\n", __func__);
+ for (i = 0; i < cyclelen; i++) {
+ j = srcu_lockdep_next(__func__, "srcu_read_lock", "synchronize_srcu",
+ "srcu_read_unlock", i, cyclelen, deadlock);
+ idx = srcu_read_lock(srcus[i]);
+ if (j >= 0)
+ synchronize_srcu(srcus[j]);
+ srcu_read_unlock(srcus[i], idx);
+ }
+ return;
+ }
+
+ if (testtype == 1) {
+ pr_info("%s: test_srcu_lockdep = %05d: SRCU/mutex %d-way %sdeadlock.\n",
+ __func__, test_srcu_lockdep, cyclelen, deadlock ? "" : "non-");
+ for (i = 0; i < cyclelen; i++) {
+ pr_info("%s: srcu_read_lock(%d), mutex_lock(%d), mutex_unlock(%d), srcu_read_unlock(%d)\n",
+ __func__, i, i, i, i);
+ idx = srcu_read_lock(srcus[i]);
+ mutex_lock(muts[i]);
+ mutex_unlock(muts[i]);
+ srcu_read_unlock(srcus[i], idx);
+
+ j = srcu_lockdep_next(__func__, "mutex_lock", "synchronize_srcu",
+ "mutex_unlock", i, cyclelen, deadlock);
+ mutex_lock(muts[i]);
+ if (j >= 0)
+ synchronize_srcu(srcus[j]);
+ mutex_unlock(muts[i]);
+ }
+ return;
+ }
+
+ if (testtype == 2) {
+ pr_info("%s: test_srcu_lockdep = %05d: SRCU/rwsem %d-way %sdeadlock.\n",
+ __func__, test_srcu_lockdep, cyclelen, deadlock ? "" : "non-");
+ for (i = 0; i < cyclelen; i++) {
+ pr_info("%s: srcu_read_lock(%d), down_read(%d), up_read(%d), srcu_read_unlock(%d)\n",
+ __func__, i, i, i, i);
+ idx = srcu_read_lock(srcus[i]);
+ down_read(rwsems[i]);
+ up_read(rwsems[i]);
+ srcu_read_unlock(srcus[i], idx);
+
+ j = srcu_lockdep_next(__func__, "down_write", "synchronize_srcu",
+ "up_write", i, cyclelen, deadlock);
+ down_write(rwsems[i]);
+ if (j >= 0)
+ synchronize_srcu(srcus[j]);
+ up_write(rwsems[i]);
+ }
+ return;
+ }
+
+err_out:
+ pr_info("%s: test_srcu_lockdep = %05d does nothing.\n", __func__, test_srcu_lockdep);
+ pr_info("%s: test_srcu_lockdep = DNNL.\n", __func__);
+ pr_info("%s: D: Deadlock if nonzero.\n", __func__);
+ pr_info("%s: NN: Test number, 0=SRCU, 1=SRCU/mutex, 2=SRCU/rwsem.\n", __func__);
+ pr_info("%s: L: Cycle length.\n", __func__);
+}
+
static int __init
rcu_torture_init(void)
{
@@ -3504,6 +3653,8 @@ rcu_torture_init(void)
if (cur_ops->init)
cur_ops->init();
+ rcu_torture_init_srcu_lockdep();
+
if (nreaders >= 0) {
nrealreaders = nreaders;
} else {
--
2.39.2
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