--- /dev/null
+/* SPDX-License-Identifier: MIT */
+
+/*
+ * Copyright © 2019 Intel Corporation
+ */
+
+#include <linux/delay.h>
+#include <linux/dma-fence.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/sched/signal.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "selftest.h"
+
+static struct kmem_cache *slab_fences;
+
+static struct mock_fence {
+ struct dma_fence base;
+ struct spinlock lock;
+} *to_mock_fence(struct dma_fence *f) {
+ return container_of(f, struct mock_fence, base);
+}
+
+static const char *mock_name(struct dma_fence *f)
+{
+ return "mock";
+}
+
+static void mock_fence_release(struct dma_fence *f)
+{
+ kmem_cache_free(slab_fences, to_mock_fence(f));
+}
+
+struct wait_cb {
+ struct dma_fence_cb cb;
+ struct task_struct *task;
+};
+
+static void mock_wakeup(struct dma_fence *f, struct dma_fence_cb *cb)
+{
+ wake_up_process(container_of(cb, struct wait_cb, cb)->task);
+}
+
+static long mock_wait(struct dma_fence *f, bool intr, long timeout)
+{
+ const int state = intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
+ struct wait_cb cb = { .task = current };
+
+ if (dma_fence_add_callback(f, &cb.cb, mock_wakeup))
+ return timeout;
+
+ while (timeout) {
+ set_current_state(state);
+
+ if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &f->flags))
+ break;
+
+ if (signal_pending_state(state, current))
+ break;
+
+ timeout = schedule_timeout(timeout);
+ }
+ __set_current_state(TASK_RUNNING);
+
+ if (!dma_fence_remove_callback(f, &cb.cb))
+ return timeout;
+
+ if (signal_pending_state(state, current))
+ return -ERESTARTSYS;
+
+ return -ETIME;
+}
+
+static const struct dma_fence_ops mock_ops = {
+ .get_driver_name = mock_name,
+ .get_timeline_name = mock_name,
+ .wait = mock_wait,
+ .release = mock_fence_release,
+};
+
+static struct dma_fence *mock_fence(void)
+{
+ struct mock_fence *f;
+
+ f = kmem_cache_alloc(slab_fences, GFP_KERNEL);
+ if (!f)
+ return NULL;
+
+ spin_lock_init(&f->lock);
+ dma_fence_init(&f->base, &mock_ops, &f->lock, 0, 0);
+
+ return &f->base;
+}
+
+static int sanitycheck(void *arg)
+{
+ struct dma_fence *f;
+
+ f = mock_fence();
+ if (!f)
+ return -ENOMEM;
+
+ dma_fence_signal(f);
+ dma_fence_put(f);
+
+ return 0;
+}
+
+static int test_signaling(void *arg)
+{
+ struct dma_fence *f;
+ int err = -EINVAL;
+
+ f = mock_fence();
+ if (!f)
+ return -ENOMEM;
+
+ if (dma_fence_is_signaled(f)) {
+ pr_err("Fence unexpectedly signaled on creation\n");
+ goto err_free;
+ }
+
+ if (dma_fence_signal(f)) {
+ pr_err("Fence reported being already signaled\n");
+ goto err_free;
+ }
+
+ if (!dma_fence_is_signaled(f)) {
+ pr_err("Fence not reporting signaled\n");
+ goto err_free;
+ }
+
+ if (!dma_fence_signal(f)) {
+ pr_err("Fence reported not being already signaled\n");
+ goto err_free;
+ }
+
+ err = 0;
+err_free:
+ dma_fence_put(f);
+ return err;
+}
+
+struct simple_cb {
+ struct dma_fence_cb cb;
+ bool seen;
+};
+
+static void simple_callback(struct dma_fence *f, struct dma_fence_cb *cb)
+{
+ smp_store_mb(container_of(cb, struct simple_cb, cb)->seen, true);
+}
+
+static int test_add_callback(void *arg)
+{
+ struct simple_cb cb = {};
+ struct dma_fence *f;
+ int err = -EINVAL;
+
+ f = mock_fence();
+ if (!f)
+ return -ENOMEM;
+
+ if (dma_fence_add_callback(f, &cb.cb, simple_callback)) {
+ pr_err("Failed to add callback, fence already signaled!\n");
+ goto err_free;
+ }
+
+ dma_fence_signal(f);
+ if (!cb.seen) {
+ pr_err("Callback failed!\n");
+ goto err_free;
+ }
+
+ err = 0;
+err_free:
+ dma_fence_put(f);
+ return err;
+}
+
+static int test_late_add_callback(void *arg)
+{
+ struct simple_cb cb = {};
+ struct dma_fence *f;
+ int err = -EINVAL;
+
+ f = mock_fence();
+ if (!f)
+ return -ENOMEM;
+
+ dma_fence_signal(f);
+
+ if (!dma_fence_add_callback(f, &cb.cb, simple_callback)) {
+ pr_err("Added callback, but fence was already signaled!\n");
+ goto err_free;
+ }
+
+ dma_fence_signal(f);
+ if (cb.seen) {
+ pr_err("Callback called after failed attachment !\n");
+ goto err_free;
+ }
+
+ err = 0;
+err_free:
+ dma_fence_put(f);
+ return err;
+}
+
+static int test_rm_callback(void *arg)
+{
+ struct simple_cb cb = {};
+ struct dma_fence *f;
+ int err = -EINVAL;
+
+ f = mock_fence();
+ if (!f)
+ return -ENOMEM;
+
+ if (dma_fence_add_callback(f, &cb.cb, simple_callback)) {
+ pr_err("Failed to add callback, fence already signaled!\n");
+ goto err_free;
+ }
+
+ if (!dma_fence_remove_callback(f, &cb.cb)) {
+ pr_err("Failed to remove callback!\n");
+ goto err_free;
+ }
+
+ dma_fence_signal(f);
+ if (cb.seen) {
+ pr_err("Callback still signaled after removal!\n");
+ goto err_free;
+ }
+
+ err = 0;
+err_free:
+ dma_fence_put(f);
+ return err;
+}
+
+static int test_late_rm_callback(void *arg)
+{
+ struct simple_cb cb = {};
+ struct dma_fence *f;
+ int err = -EINVAL;
+
+ f = mock_fence();
+ if (!f)
+ return -ENOMEM;
+
+ if (dma_fence_add_callback(f, &cb.cb, simple_callback)) {
+ pr_err("Failed to add callback, fence already signaled!\n");
+ goto err_free;
+ }
+
+ dma_fence_signal(f);
+ if (!cb.seen) {
+ pr_err("Callback failed!\n");
+ goto err_free;
+ }
+
+ if (dma_fence_remove_callback(f, &cb.cb)) {
+ pr_err("Callback removal succeed after being executed!\n");
+ goto err_free;
+ }
+
+ err = 0;
+err_free:
+ dma_fence_put(f);
+ return err;
+}
+
+static int test_status(void *arg)
+{
+ struct dma_fence *f;
+ int err = -EINVAL;
+
+ f = mock_fence();
+ if (!f)
+ return -ENOMEM;
+
+ if (dma_fence_get_status(f)) {
+ pr_err("Fence unexpectedly has signaled status on creation\n");
+ goto err_free;
+ }
+
+ dma_fence_signal(f);
+ if (!dma_fence_get_status(f)) {
+ pr_err("Fence not reporting signaled status\n");
+ goto err_free;
+ }
+
+ err = 0;
+err_free:
+ dma_fence_put(f);
+ return err;
+}
+
+static int test_error(void *arg)
+{
+ struct dma_fence *f;
+ int err = -EINVAL;
+
+ f = mock_fence();
+ if (!f)
+ return -ENOMEM;
+
+ dma_fence_set_error(f, -EIO);
+
+ if (dma_fence_get_status(f)) {
+ pr_err("Fence unexpectedly has error status before signal\n");
+ goto err_free;
+ }
+
+ dma_fence_signal(f);
+ if (dma_fence_get_status(f) != -EIO) {
+ pr_err("Fence not reporting error status, got %d\n",
+ dma_fence_get_status(f));
+ goto err_free;
+ }
+
+ err = 0;
+err_free:
+ dma_fence_put(f);
+ return err;
+}
+
+static int test_wait(void *arg)
+{
+ struct dma_fence *f;
+ int err = -EINVAL;
+
+ f = mock_fence();
+ if (!f)
+ return -ENOMEM;
+
+ if (dma_fence_wait_timeout(f, false, 0) != -ETIME) {
+ pr_err("Wait reported complete before being signaled\n");
+ goto err_free;
+ }
+
+ dma_fence_signal(f);
+
+ if (dma_fence_wait_timeout(f, false, 0) != 0) {
+ pr_err("Wait reported incomplete after being signaled\n");
+ goto err_free;
+ }
+
+ err = 0;
+err_free:
+ dma_fence_signal(f);
+ dma_fence_put(f);
+ return err;
+}
+
+struct wait_timer {
+ struct timer_list timer;
+ struct dma_fence *f;
+};
+
+static void wait_timer(struct timer_list *timer)
+{
+ struct wait_timer *wt = from_timer(wt, timer, timer);
+
+ dma_fence_signal(wt->f);
+}
+
+static int test_wait_timeout(void *arg)
+{
+ struct wait_timer wt;
+ int err = -EINVAL;
+
+ timer_setup(&wt.timer, wait_timer, 0);
+
+ wt.f = mock_fence();
+ if (!wt.f)
+ return -ENOMEM;
+
+ if (dma_fence_wait_timeout(wt.f, false, 1) != -ETIME) {
+ pr_err("Wait reported complete before being signaled\n");
+ goto err_free;
+ }
+
+ mod_timer(&wt.timer, jiffies + 1);
+
+ if (dma_fence_wait_timeout(wt.f, false, 2) == -ETIME) {
+ if (timer_pending(&wt.timer)) {
+ pr_notice("Timer did not fire within the jiffie!\n");
+ err = 0; /* not our fault! */
+ } else {
+ pr_err("Wait reported incomplete after timeout\n");
+ }
+ goto err_free;
+ }
+
+ err = 0;
+err_free:
+ del_timer_sync(&wt.timer);
+ dma_fence_signal(wt.f);
+ dma_fence_put(wt.f);
+ return err;
+}
+
+static int test_stub(void *arg)
+{
+ struct dma_fence *f[64];
+ int err = -EINVAL;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(f); i++) {
+ f[i] = dma_fence_get_stub();
+ if (!dma_fence_is_signaled(f[i])) {
+ pr_err("Obtained unsignaled stub fence!\n");
+ goto err;
+ }
+ }
+
+ err = 0;
+err:
+ while (i--)
+ dma_fence_put(f[i]);
+ return err;
+}
+
+/* Now off to the races! */
+
+struct race_thread {
+ struct dma_fence __rcu **fences;
+ struct task_struct *task;
+ bool before;
+ int id;
+};
+
+static void __wait_for_callbacks(struct dma_fence *f)
+{
+ spin_lock_irq(f->lock);
+ spin_unlock_irq(f->lock);
+}
+
+static int thread_signal_callback(void *arg)
+{
+ const struct race_thread *t = arg;
+ unsigned long pass = 0;
+ unsigned long miss = 0;
+ int err = 0;
+
+ while (!err && !kthread_should_stop()) {
+ struct dma_fence *f1, *f2;
+ struct simple_cb cb;
+
+ f1 = mock_fence();
+ if (!f1) {
+ err = -ENOMEM;
+ break;
+ }
+
+ rcu_assign_pointer(t->fences[t->id], f1);
+ smp_wmb();
+
+ rcu_read_lock();
+ do {
+ f2 = dma_fence_get_rcu_safe(&t->fences[!t->id]);
+ } while (!f2 && !kthread_should_stop());
+ rcu_read_unlock();
+
+ if (t->before)
+ dma_fence_signal(f1);
+
+ smp_store_mb(cb.seen, false);
+ if (!f2 || dma_fence_add_callback(f2, &cb.cb, simple_callback))
+ miss++, cb.seen = true;
+
+ if (!t->before)
+ dma_fence_signal(f1);
+
+ if (!cb.seen) {
+ dma_fence_wait(f2, false);
+ __wait_for_callbacks(f2);
+ }
+
+ if (!READ_ONCE(cb.seen)) {
+ pr_err("Callback not seen on thread %d, pass %lu (%lu misses), signaling %s add_callback; fence signaled? %s\n",
+ t->id, pass, miss,
+ t->before ? "before" : "after",
+ dma_fence_is_signaled(f2) ? "yes" : "no");
+ err = -EINVAL;
+ }
+
+ dma_fence_put(f2);
+
+ rcu_assign_pointer(t->fences[t->id], NULL);
+ smp_wmb();
+
+ dma_fence_put(f1);
+
+ pass++;
+ }
+
+ pr_info("%s[%d] completed %lu passes, %lu misses\n",
+ __func__, t->id, pass, miss);
+ return err;
+}
+
+static int race_signal_callback(void *arg)
+{
+ struct dma_fence __rcu *f[2] = {};
+ int ret = 0;
+ int pass;
+
+ for (pass = 0; !ret && pass <= 1; pass++) {
+ struct race_thread t[2];
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(t); i++) {
+ t[i].fences = f;
+ t[i].id = i;
+ t[i].before = pass;
+ t[i].task = kthread_run(thread_signal_callback, &t[i],
+ "dma-fence:%d", i);
+ get_task_struct(t[i].task);
+ }
+
+ msleep(50);
+
+ for (i = 0; i < ARRAY_SIZE(t); i++) {
+ int err;
+
+ err = kthread_stop(t[i].task);
+ if (err && !ret)
+ ret = err;
+
+ put_task_struct(t[i].task);
+ }
+ }
+
+ return ret;
+}
+
+int dma_fence(void)
+{
+ static const struct subtest tests[] = {
+ SUBTEST(sanitycheck),
+ SUBTEST(test_signaling),
+ SUBTEST(test_add_callback),
+ SUBTEST(test_late_add_callback),
+ SUBTEST(test_rm_callback),
+ SUBTEST(test_late_rm_callback),
+ SUBTEST(test_status),
+ SUBTEST(test_error),
+ SUBTEST(test_wait),
+ SUBTEST(test_wait_timeout),
+ SUBTEST(test_stub),
+ SUBTEST(race_signal_callback),
+ };
+ int ret;
+
+ pr_info("sizeof(dma_fence)=%lu\n", sizeof(struct dma_fence));
+
+ slab_fences = KMEM_CACHE(mock_fence,
+ SLAB_TYPESAFE_BY_RCU |
+ SLAB_HWCACHE_ALIGN);
+ if (!slab_fences)
+ return -ENOMEM;
+
+ ret = subtests(tests, NULL);
+
+ kmem_cache_destroy(slab_fences);
+
+ return ret;
+}
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