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Subject[PATCH 1/4] locktorture: Support rwlocks
Date
Add a "rw_lock" torture test to stress kernel rwlocks and their irq
variant. Reader critical regions are 5x longer than writers. As such
a similar ratio of lock acquisitions is seen in the statistics. In the
case of massive contention, both hold the lock for 1/10 of a second.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
Documentation/locking/locktorture.txt | 5 +
kernel/locking/locktorture.c | 115 ++++++++++++++++++++-
.../selftests/rcutorture/configs/lock/CFLIST | 1 +
.../selftests/rcutorture/configs/lock/LOCK04 | 6 ++
.../selftests/rcutorture/configs/lock/LOCK04.boot | 1 +
5 files changed, 125 insertions(+), 3 deletions(-)
create mode 100644 tools/testing/selftests/rcutorture/configs/lock/LOCK04
create mode 100644 tools/testing/selftests/rcutorture/configs/lock/LOCK04.boot

diff --git a/Documentation/locking/locktorture.txt b/Documentation/locking/locktorture.txt
index be71501..619f2bb 100644
--- a/Documentation/locking/locktorture.txt
+++ b/Documentation/locking/locktorture.txt
@@ -45,6 +45,11 @@ torture_type Type of lock to torture. By default, only spinlocks will
o "spin_lock_irq": spin_lock_irq() and spin_unlock_irq()
pairs.

+ o "rw_lock": read/write lock() and unlock() rwlock pairs.
+
+ o "rw_lock_irq": read/write lock_irq() and unlock_irq()
+ rwlock pairs.
+
o "mutex_lock": mutex_lock() and mutex_unlock() pairs.

o "rwsem_lock": read/write down() and up() semaphore pairs.
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 540d5df..0762b25 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -27,6 +27,7 @@
#include <linux/kthread.h>
#include <linux/err.h>
#include <linux/spinlock.h>
+#include <linux/rwlock.h>
#include <linux/mutex.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
@@ -229,6 +230,110 @@ static struct lock_torture_ops spin_lock_irq_ops = {
.name = "spin_lock_irq"
};

+static DEFINE_RWLOCK(torture_rwlock);
+
+static int torture_rwlock_write_lock(void) __acquires(torture_rwlock)
+{
+ write_lock(&torture_rwlock);
+ return 0;
+}
+
+static void torture_rwlock_write_delay(struct torture_random_state *trsp)
+{
+ const unsigned long shortdelay_us = 2;
+ const unsigned long longdelay_ms = 100;
+
+ /* We want a short delay mostly to emulate likely code, and
+ * we want a long delay occasionally to force massive contention.
+ */
+ if (!(torture_random(trsp) %
+ (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
+ mdelay(longdelay_ms);
+ else
+ udelay(shortdelay_us);
+}
+
+static void torture_rwlock_write_unlock(void) __releases(torture_rwlock)
+{
+ write_unlock(&torture_rwlock);
+}
+
+static int torture_rwlock_read_lock(void) __acquires(torture_rwlock)
+{
+ read_lock(&torture_rwlock);
+ return 0;
+}
+
+static void torture_rwlock_read_delay(struct torture_random_state *trsp)
+{
+ const unsigned long shortdelay_us = 10;
+ const unsigned long longdelay_ms = 100;
+
+ /* We want a short delay mostly to emulate likely code, and
+ * we want a long delay occasionally to force massive contention.
+ */
+ if (!(torture_random(trsp) %
+ (cxt.nrealreaders_stress * 2000 * longdelay_ms)))
+ mdelay(longdelay_ms);
+ else
+ udelay(shortdelay_us);
+}
+
+static void torture_rwlock_read_unlock(void) __releases(torture_rwlock)
+{
+ read_unlock(&torture_rwlock);
+}
+
+static struct lock_torture_ops rw_lock_ops = {
+ .writelock = torture_rwlock_write_lock,
+ .write_delay = torture_rwlock_write_delay,
+ .writeunlock = torture_rwlock_write_unlock,
+ .readlock = torture_rwlock_read_lock,
+ .read_delay = torture_rwlock_read_delay,
+ .readunlock = torture_rwlock_read_unlock,
+ .name = "rw_lock"
+};
+
+static int torture_rwlock_write_lock_irq(void) __acquires(torture_rwlock)
+{
+ unsigned long flags;
+
+ write_lock_irqsave(&torture_rwlock, flags);
+ cxt.cur_ops->flags = flags;
+ return 0;
+}
+
+static void torture_rwlock_write_unlock_irq(void)
+__releases(torture_rwlock)
+{
+ write_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
+}
+
+static int torture_rwlock_read_lock_irq(void) __acquires(torture_rwlock)
+{
+ unsigned long flags;
+
+ read_lock_irqsave(&torture_rwlock, flags);
+ cxt.cur_ops->flags = flags;
+ return 0;
+}
+
+static void torture_rwlock_read_unlock_irq(void)
+__releases(torture_rwlock)
+{
+ write_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
+}
+
+static struct lock_torture_ops rw_lock_irq_ops = {
+ .writelock = torture_rwlock_write_lock_irq,
+ .write_delay = torture_rwlock_write_delay,
+ .writeunlock = torture_rwlock_write_unlock_irq,
+ .readlock = torture_rwlock_read_lock_irq,
+ .read_delay = torture_rwlock_read_delay,
+ .readunlock = torture_rwlock_read_unlock_irq,
+ .name = "rw_lock_irq"
+};
+
static DEFINE_MUTEX(torture_mutex);

static int torture_mutex_lock(void) __acquires(torture_mutex)
@@ -535,8 +640,11 @@ static int __init lock_torture_init(void)
int i, j;
int firsterr = 0;
static struct lock_torture_ops *torture_ops[] = {
- &lock_busted_ops, &spin_lock_ops, &spin_lock_irq_ops,
- &mutex_lock_ops, &rwsem_lock_ops,
+ &lock_busted_ops,
+ &spin_lock_ops, &spin_lock_irq_ops,
+ &rw_lock_ops, &rw_lock_irq_ops,
+ &mutex_lock_ops,
+ &rwsem_lock_ops,
};

if (!torture_init_begin(torture_type, verbose, &torture_runnable))
@@ -571,7 +679,8 @@ static int __init lock_torture_init(void)
cxt.debug_lock = true;
#endif
#ifdef CONFIG_DEBUG_SPINLOCK
- if (strncmp(torture_type, "spin", 4) == 0)
+ if ((strncmp(torture_type, "spin", 4) == 0) ||
+ (strncmp(torture_type, "rw_lock", 7) == 0))
cxt.debug_lock = true;
#endif

diff --git a/tools/testing/selftests/rcutorture/configs/lock/CFLIST b/tools/testing/selftests/rcutorture/configs/lock/CFLIST
index 6108137..6910b73 100644
--- a/tools/testing/selftests/rcutorture/configs/lock/CFLIST
+++ b/tools/testing/selftests/rcutorture/configs/lock/CFLIST
@@ -1,3 +1,4 @@
LOCK01
LOCK02
LOCK03
+LOCK04
\ No newline at end of file
diff --git a/tools/testing/selftests/rcutorture/configs/lock/LOCK04 b/tools/testing/selftests/rcutorture/configs/lock/LOCK04
new file mode 100644
index 0000000..1d1da14
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/lock/LOCK04
@@ -0,0 +1,6 @@
+CONFIG_SMP=y
+CONFIG_NR_CPUS=4
+CONFIG_HOTPLUG_CPU=y
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
diff --git a/tools/testing/selftests/rcutorture/configs/lock/LOCK04.boot b/tools/testing/selftests/rcutorture/configs/lock/LOCK04.boot
new file mode 100644
index 0000000..48c04fe
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/lock/LOCK04.boot
@@ -0,0 +1 @@
+locktorture.torture_type=rw_lock
--
1.8.4.5


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