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locking/ww_mutex: Add kselftests for ww_mutex stress
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Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Nicolai Hähnle <nhaehnle@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20161201114711.28697-8-chris@chris-wilson.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Chris Wilson authored and Ingo Molnar committed Jan 14, 2017
1 parent d1b42b8 commit 2a0c112
Showing 1 changed file with 254 additions and 0 deletions.
254 changes: 254 additions & 0 deletions kernel/locking/test-ww_mutex.c
Original file line number Diff line number Diff line change
Expand Up @@ -19,8 +19,10 @@
#include <linux/kernel.h>

#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/ww_mutex.h>

Expand Down Expand Up @@ -348,6 +350,246 @@ static int test_cycle(unsigned int ncpus)
return 0;
}

struct stress {
struct work_struct work;
struct ww_mutex *locks;
int nlocks;
int nloops;
};

static int *get_random_order(int count)
{
int *order;
int n, r, tmp;

order = kmalloc_array(count, sizeof(*order), GFP_TEMPORARY);
if (!order)
return order;

for (n = 0; n < count; n++)
order[n] = n;

for (n = count - 1; n > 1; n--) {
r = get_random_int() % (n + 1);
if (r != n) {
tmp = order[n];
order[n] = order[r];
order[r] = tmp;
}
}

return order;
}

static void dummy_load(struct stress *stress)
{
usleep_range(1000, 2000);
}

static void stress_inorder_work(struct work_struct *work)
{
struct stress *stress = container_of(work, typeof(*stress), work);
const int nlocks = stress->nlocks;
struct ww_mutex *locks = stress->locks;
struct ww_acquire_ctx ctx;
int *order;

order = get_random_order(nlocks);
if (!order)
return;

ww_acquire_init(&ctx, &ww_class);

do {
int contended = -1;
int n, err;

retry:
err = 0;
for (n = 0; n < nlocks; n++) {
if (n == contended)
continue;

err = ww_mutex_lock(&locks[order[n]], &ctx);
if (err < 0)
break;
}
if (!err)
dummy_load(stress);

if (contended > n)
ww_mutex_unlock(&locks[order[contended]]);
contended = n;
while (n--)
ww_mutex_unlock(&locks[order[n]]);

if (err == -EDEADLK) {
ww_mutex_lock_slow(&locks[order[contended]], &ctx);
goto retry;
}

if (err) {
pr_err_once("stress (%s) failed with %d\n",
__func__, err);
break;
}
} while (--stress->nloops);

ww_acquire_fini(&ctx);

kfree(order);
kfree(stress);
}

struct reorder_lock {
struct list_head link;
struct ww_mutex *lock;
};

static void stress_reorder_work(struct work_struct *work)
{
struct stress *stress = container_of(work, typeof(*stress), work);
LIST_HEAD(locks);
struct ww_acquire_ctx ctx;
struct reorder_lock *ll, *ln;
int *order;
int n, err;

order = get_random_order(stress->nlocks);
if (!order)
return;

for (n = 0; n < stress->nlocks; n++) {
ll = kmalloc(sizeof(*ll), GFP_KERNEL);
if (!ll)
goto out;

ll->lock = &stress->locks[order[n]];
list_add(&ll->link, &locks);
}
kfree(order);
order = NULL;

ww_acquire_init(&ctx, &ww_class);

do {
list_for_each_entry(ll, &locks, link) {
err = ww_mutex_lock(ll->lock, &ctx);
if (!err)
continue;

ln = ll;
list_for_each_entry_continue_reverse(ln, &locks, link)
ww_mutex_unlock(ln->lock);

if (err != -EDEADLK) {
pr_err_once("stress (%s) failed with %d\n",
__func__, err);
break;
}

ww_mutex_lock_slow(ll->lock, &ctx);
list_move(&ll->link, &locks); /* restarts iteration */
}

dummy_load(stress);
list_for_each_entry(ll, &locks, link)
ww_mutex_unlock(ll->lock);
} while (--stress->nloops);

ww_acquire_fini(&ctx);

out:
list_for_each_entry_safe(ll, ln, &locks, link)
kfree(ll);
kfree(order);
kfree(stress);
}

static void stress_one_work(struct work_struct *work)
{
struct stress *stress = container_of(work, typeof(*stress), work);
const int nlocks = stress->nlocks;
struct ww_mutex *lock = stress->locks + (get_random_int() % nlocks);
int err;

do {
err = ww_mutex_lock(lock, NULL);
if (!err) {
dummy_load(stress);
ww_mutex_unlock(lock);
} else {
pr_err_once("stress (%s) failed with %d\n",
__func__, err);
break;
}
} while (--stress->nloops);

kfree(stress);
}

#define STRESS_INORDER BIT(0)
#define STRESS_REORDER BIT(1)
#define STRESS_ONE BIT(2)
#define STRESS_ALL (STRESS_INORDER | STRESS_REORDER | STRESS_ONE)

static int stress(int nlocks, int nthreads, int nloops, unsigned int flags)
{
struct ww_mutex *locks;
int n;

locks = kmalloc_array(nlocks, sizeof(*locks), GFP_KERNEL);
if (!locks)
return -ENOMEM;

for (n = 0; n < nlocks; n++)
ww_mutex_init(&locks[n], &ww_class);

for (n = 0; nthreads; n++) {
struct stress *stress;
void (*fn)(struct work_struct *work);

fn = NULL;
switch (n & 3) {
case 0:
if (flags & STRESS_INORDER)
fn = stress_inorder_work;
break;
case 1:
if (flags & STRESS_REORDER)
fn = stress_reorder_work;
break;
case 2:
if (flags & STRESS_ONE)
fn = stress_one_work;
break;
}

if (!fn)
continue;

stress = kmalloc(sizeof(*stress), GFP_KERNEL);
if (!stress)
break;

INIT_WORK(&stress->work, fn);
stress->locks = locks;
stress->nlocks = nlocks;
stress->nloops = nloops;

queue_work(wq, &stress->work);
nthreads--;
}

flush_workqueue(wq);

for (n = 0; n < nlocks; n++)
ww_mutex_destroy(&locks[n]);
kfree(locks);

return 0;
}

static int __init test_ww_mutex_init(void)
{
int ncpus = num_online_cpus();
Expand Down Expand Up @@ -377,6 +619,18 @@ static int __init test_ww_mutex_init(void)
if (ret)
return ret;

ret = stress(16, 2*ncpus, 1<<10, STRESS_INORDER);
if (ret)
return ret;

ret = stress(16, 2*ncpus, 1<<10, STRESS_REORDER);
if (ret)
return ret;

ret = stress(4096, hweight32(STRESS_ALL)*ncpus, 1<<12, STRESS_ALL);
if (ret)
return ret;

return 0;
}

Expand Down

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