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locktorture: Support rtmutex torturing 

Real time mutexes is one of the few general primitives
that we do not have in locktorture. Address this -- a few
considerations:

o To spice things up, enable competing thread(s) to become
rt, such that we can stress different prio boosting paths
in the rtmutex code. Introduce a ->task_boost callback,
only used by rtmutex-torturer. Tasks will boost/deboost
around every 50k (arbitrarily) lock/unlock operations.

o Hold times are similar to what we have for other locks:
only occasionally having longer hold times (per ~200k ops).
So we roughly do two full rt boost+deboosting ops with
short hold times.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Davidlohr Bueso 2015-07-22 14:07:27 -07:00 committed by Paul E. McKenney
parent 19a5ecde08
commit 095777c417
5 changed files with 124 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/locking/locktorture.txt
View File

@ -52,6 +52,9 @@ torture_type Type of lock to torture. By default, only spinlocks will
o "mutex_lock": mutex_lock() and mutex_unlock() pairs.
o "rtmutex_lock": rtmutex_lock() and rtmutex_unlock()
pairs. Kernel must have CONFIG_RT_MUTEX=y.
o "rwsem_lock": read/write down() and up() semaphore pairs.
torture_runnable Start locktorture at boot time in the case where the

114
kernel/locking/locktorture.c
View File

@ -17,12 +17,14 @@
*
* Copyright (C) IBM Corporation, 2014
*
* Author: Paul E. McKenney <paulmck@us.ibm.com>
* Authors: Paul E. McKenney <paulmck@us.ibm.com>
* Davidlohr Bueso <dave@stgolabs.net>
* Based on kernel/rcu/torture.c.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/sched/rt.h>
#include <linux/spinlock.h>
#include <linux/rwlock.h>
#include <linux/mutex.h>
@ -91,11 +93,13 @@ struct lock_torture_ops {
void (*init)(void);
int (*writelock)(void);
void (*write_delay)(struct torture_random_state *trsp);
void (*task_boost)(struct torture_random_state *trsp);
void (*writeunlock)(void);
int (*readlock)(void);
void (*read_delay)(struct torture_random_state *trsp);
void (*readunlock)(void);
unsigned long flags;
unsigned long flags; /* for irq spinlocks */
const char *name;
};
@ -139,9 +143,15 @@ static void torture_lock_busted_write_unlock(void)
/* BUGGY, do not use in real life!!! */
}
static void torture_boost_dummy(struct torture_random_state *trsp)
{
/* Only rtmutexes care about priority */
}
static struct lock_torture_ops lock_busted_ops = {
.writelock = torture_lock_busted_write_lock,
.write_delay = torture_lock_busted_write_delay,
.task_boost = torture_boost_dummy,
.writeunlock = torture_lock_busted_write_unlock,
.readlock = NULL,
.read_delay = NULL,
@ -185,6 +195,7 @@ static void torture_spin_lock_write_unlock(void) __releases(torture_spinlock)
static struct lock_torture_ops spin_lock_ops = {
.writelock = torture_spin_lock_write_lock,
.write_delay = torture_spin_lock_write_delay,
.task_boost = torture_boost_dummy,
.writeunlock = torture_spin_lock_write_unlock,
.readlock = NULL,
.read_delay = NULL,
@ -211,6 +222,7 @@ __releases(torture_spinlock)
static struct lock_torture_ops spin_lock_irq_ops = {
.writelock = torture_spin_lock_write_lock_irq,
.write_delay = torture_spin_lock_write_delay,
.task_boost = torture_boost_dummy,
.writeunlock = torture_lock_spin_write_unlock_irq,
.readlock = NULL,
.read_delay = NULL,
@ -275,6 +287,7 @@ static void torture_rwlock_read_unlock(void) __releases(torture_rwlock)
static struct lock_torture_ops rw_lock_ops = {
.writelock = torture_rwlock_write_lock,
.write_delay = torture_rwlock_write_delay,
.task_boost = torture_boost_dummy,
.writeunlock = torture_rwlock_write_unlock,
.readlock = torture_rwlock_read_lock,
.read_delay = torture_rwlock_read_delay,
@ -315,6 +328,7 @@ __releases(torture_rwlock)
static struct lock_torture_ops rw_lock_irq_ops = {
.writelock = torture_rwlock_write_lock_irq,
.write_delay = torture_rwlock_write_delay,
.task_boost = torture_boost_dummy,
.writeunlock = torture_rwlock_write_unlock_irq,
.readlock = torture_rwlock_read_lock_irq,
.read_delay = torture_rwlock_read_delay,
@ -354,6 +368,7 @@ static void torture_mutex_unlock(void) __releases(torture_mutex)
static struct lock_torture_ops mutex_lock_ops = {
.writelock = torture_mutex_lock,
.write_delay = torture_mutex_delay,
.task_boost = torture_boost_dummy,
.writeunlock = torture_mutex_unlock,
.readlock = NULL,
.read_delay = NULL,
@ -361,6 +376,90 @@ static struct lock_torture_ops mutex_lock_ops = {
.name = "mutex_lock"
};
#ifdef CONFIG_RT_MUTEXES
static DEFINE_RT_MUTEX(torture_rtmutex);
static int torture_rtmutex_lock(void) __acquires(torture_rtmutex)
{
rt_mutex_lock(&torture_rtmutex);
return 0;
}
static void torture_rtmutex_boost(struct torture_random_state *trsp)
{
int policy;
struct sched_param param;
const unsigned int factor = 50000; /* yes, quite arbitrary */
if (!rt_task(current)) {
/*
* (1) Boost priority once every ~50k operations. When the
* task tries to take the lock, the rtmutex it will account
* for the new priority, and do any corresponding pi-dance.
*/
if (!(torture_random(trsp) %
(cxt.nrealwriters_stress * factor))) {
policy = SCHED_FIFO;
param.sched_priority = MAX_RT_PRIO - 1;
} else /* common case, do nothing */
return;
} else {
/*
* The task will remain boosted for another ~500k operations,
* then restored back to its original prio, and so forth.
*
* When @trsp is nil, we want to force-reset the task for
* stopping the kthread.
*/
if (!trsp || !(torture_random(trsp) %
(cxt.nrealwriters_stress * factor * 2))) {
policy = SCHED_NORMAL;
param.sched_priority = 0;
} else /* common case, do nothing */
return;
}
sched_setscheduler_nocheck(current, policy, &param);
}
static void torture_rtmutex_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);
if (!(torture_random(trsp) %
(cxt.nrealwriters_stress * 2 * shortdelay_us)))
udelay(shortdelay_us);
#ifdef CONFIG_PREEMPT
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
preempt_schedule(); /* Allow test to be preempted. */
#endif
}
static void torture_rtmutex_unlock(void) __releases(torture_rtmutex)
{
rt_mutex_unlock(&torture_rtmutex);
}
static struct lock_torture_ops rtmutex_lock_ops = {
.writelock = torture_rtmutex_lock,
.write_delay = torture_rtmutex_delay,
.task_boost = torture_rtmutex_boost,
.writeunlock = torture_rtmutex_unlock,
.readlock = NULL,
.read_delay = NULL,
.readunlock = NULL,
.name = "rtmutex_lock"
};
#endif
static DECLARE_RWSEM(torture_rwsem);
static int torture_rwsem_down_write(void) __acquires(torture_rwsem)
{
@ -419,6 +518,7 @@ static void torture_rwsem_up_read(void) __releases(torture_rwsem)
static struct lock_torture_ops rwsem_lock_ops = {
.writelock = torture_rwsem_down_write,
.write_delay = torture_rwsem_write_delay,
.task_boost = torture_boost_dummy,
.writeunlock = torture_rwsem_up_write,
.readlock = torture_rwsem_down_read,
.read_delay = torture_rwsem_read_delay,
@ -442,6 +542,7 @@ static int lock_torture_writer(void *arg)
if ((torture_random(&rand) & 0xfffff) == 0)
schedule_timeout_uninterruptible(1);
cxt.cur_ops->task_boost(&rand);
cxt.cur_ops->writelock();
if (WARN_ON_ONCE(lock_is_write_held))
lwsp->n_lock_fail++;
@ -456,6 +557,8 @@ static int lock_torture_writer(void *arg)
stutter_wait("lock_torture_writer");
} while (!torture_must_stop());
cxt.cur_ops->task_boost(NULL); /* reset prio */
torture_kthread_stopping("lock_torture_writer");
return 0;
}
@ -642,6 +745,9 @@ static int __init lock_torture_init(void)
&spin_lock_ops, &spin_lock_irq_ops,
&rw_lock_ops, &rw_lock_irq_ops,
&mutex_lock_ops,
#ifdef CONFIG_RT_MUTEXES
&rtmutex_lock_ops,
#endif
&rwsem_lock_ops,
};
@ -676,6 +782,10 @@ static int __init lock_torture_init(void)
if (strncmp(torture_type, "mutex", 5) == 0)
cxt.debug_lock = true;
#endif
#ifdef CONFIG_DEBUG_RT_MUTEXES
if (strncmp(torture_type, "rtmutex", 7) == 0)
cxt.debug_lock = true;
#endif
#ifdef CONFIG_DEBUG_SPINLOCK
if ((strncmp(torture_type, "spin", 4) == 0) ||
(strncmp(torture_type, "rw_lock", 7) == 0))

3
tools/testing/selftests/rcutorture/configs/lock/CFLIST
View File

@ -1,4 +1,5 @@
LOCK01
LOCK02
LOCK03
LOCK04
LOCK04
LOCK05

6
tools/testing/selftests/rcutorture/configs/lock/LOCK05 Normal file
View File

@ -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

1
tools/testing/selftests/rcutorture/configs/lock/LOCK05.boot Normal file
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@ -0,0 +1 @@
locktorture.torture_type=rtmutex_lock