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Date: Mon, 20 Mar 2023 18:08:17 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: rcu@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, kernel-team@...a.com,
rostedt@...dmis.org, John Stultz <jstultz@...gle.com>,
Davidlohr Bueso <dave@...olabs.net>,
"Paul E. McKenney" <paulmck@...nel.org>,
Josh Triplett <josh@...htriplett.org>,
Joel Fernandes <joel@...lfernandes.org>,
Juri Lelli <juri.lelli@...hat.com>,
Valentin Schneider <vschneid@...hat.com>,
Dietmar Eggemann <dietmar.eggemann@....com>,
kernel-team@...roid.com, Connor O'Brien <connoro@...gle.com>
Subject: [PATCH locktorture 1/5] locktorture: Add nested_[un]lock() hooks and nlocks parameter
From: John Stultz <jstultz@...gle.com>
In order to extend locktorture to support lock nesting, add
nested_lock() and nested_unlock() hooks to the torture ops.
These take a 32bit lockset mask which is generated at random,
so some number of locks will be taken before the main lock is
taken and released afterwards.
Additionally, add nested_locks module parameter to allow
specifying the number of nested locks to be used.
This has been helpful to uncover issues in the proxy-exec
series development.
This was inspired by locktorture extensions originally implemented
by Connor O'Brien, for stress testing the proxy-execution series:
https://lore.kernel.org/lkml/20221003214501.2050087-12-connoro@google.com/
Cc: Davidlohr Bueso <dave@...olabs.net>
Cc: "Paul E. McKenney" <paulmck@...nel.org>
Cc: Josh Triplett <josh@...htriplett.org>
Cc: Joel Fernandes <joel@...lfernandes.org>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Valentin Schneider <vschneid@...hat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>
Cc: kernel-team@...roid.com
Reviewed-by: Davidlohr Bueso <dave@...olabs.net>
Co-developed-by: Connor O'Brien <connoro@...gle.com>
Signed-off-by: Connor O'Brien <connoro@...gle.com>
Signed-off-by: John Stultz <jstultz@...gle.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
kernel/locking/locktorture.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index f04b1978899d..a8519af25ece 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -51,6 +51,9 @@ torture_param(int, rt_boost, 2,
torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens.");
torture_param(int, verbose, 1,
"Enable verbose debugging printk()s");
+torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)");
+/* Going much higher trips "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" errors */
+#define MAX_NESTED_LOCKS 8
static char *torture_type = "spin_lock";
module_param(torture_type, charp, 0444);
@@ -79,10 +82,12 @@ static void lock_torture_cleanup(void);
struct lock_torture_ops {
void (*init)(void);
void (*exit)(void);
+ int (*nested_lock)(int tid, u32 lockset);
int (*writelock)(int tid);
void (*write_delay)(struct torture_random_state *trsp);
void (*task_boost)(struct torture_random_state *trsp);
void (*writeunlock)(int tid);
+ void (*nested_unlock)(int tid, u32 lockset);
int (*readlock)(int tid);
void (*read_delay)(struct torture_random_state *trsp);
void (*readunlock)(int tid);
@@ -684,6 +689,7 @@ static int lock_torture_writer(void *arg)
struct lock_stress_stats *lwsp = arg;
int tid = lwsp - cxt.lwsa;
DEFINE_TORTURE_RANDOM(rand);
+ u32 lockset_mask;
VERBOSE_TOROUT_STRING("lock_torture_writer task started");
set_user_nice(current, MAX_NICE);
@@ -692,7 +698,10 @@ static int lock_torture_writer(void *arg)
if ((torture_random(&rand) & 0xfffff) == 0)
schedule_timeout_uninterruptible(1);
+ lockset_mask = torture_random(&rand);
cxt.cur_ops->task_boost(&rand);
+ if (cxt.cur_ops->nested_lock)
+ cxt.cur_ops->nested_lock(tid, lockset_mask);
cxt.cur_ops->writelock(tid);
if (WARN_ON_ONCE(lock_is_write_held))
lwsp->n_lock_fail++;
@@ -705,6 +714,8 @@ static int lock_torture_writer(void *arg)
lock_is_write_held = false;
WRITE_ONCE(last_lock_release, jiffies);
cxt.cur_ops->writeunlock(tid);
+ if (cxt.cur_ops->nested_unlock)
+ cxt.cur_ops->nested_unlock(tid, lockset_mask);
stutter_wait("lock_torture_writer");
} while (!torture_must_stop());
@@ -845,11 +856,11 @@ lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
const char *tag)
{
pr_alert("%s" TORTURE_FLAG
- "--- %s%s: nwriters_stress=%d nreaders_stress=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
+ "--- %s%s: nwriters_stress=%d nreaders_stress=%d nested_locks=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
torture_type, tag, cxt.debug_lock ? " [debug]": "",
- cxt.nrealwriters_stress, cxt.nrealreaders_stress, stat_interval,
- verbose, shuffle_interval, stutter, shutdown_secs,
- onoff_interval, onoff_holdoff);
+ cxt.nrealwriters_stress, cxt.nrealreaders_stress,
+ nested_locks, stat_interval, verbose, shuffle_interval,
+ stutter, shutdown_secs, onoff_interval, onoff_holdoff);
}
static void lock_torture_cleanup(void)
@@ -1068,6 +1079,10 @@ static int __init lock_torture_init(void)
}
}
+ /* cap nested_locks to MAX_NESTED_LOCKS */
+ if (nested_locks > MAX_NESTED_LOCKS)
+ nested_locks = MAX_NESTED_LOCKS;
+
if (cxt.cur_ops->readlock) {
reader_tasks = kcalloc(cxt.nrealreaders_stress,
sizeof(reader_tasks[0]),
--
2.40.0.rc2
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