drm: Revert syncobj timeline changes.

Daniel suggested I submit this, since we're still seeing regressions
from it.  This is a revert to before 48197bc564c7 ("drm: add syncobj
timeline support v9") and its followon fixes.

Fixes this on first V3D testcase execution:

[   48.767088] ============================================
[   48.772410] WARNING: possible recursive locking detected
[   48.777739] 4.19.0-rc6+ #489 Not tainted
[   48.781668] --------------------------------------------
[   48.786993] shader_runner/3284 is trying to acquire lock:
[   48.792408] ce309d7f (&(&array->lock)->rlock){....}, at: dma_fence_add_callback+0x30/0x23c
[   48.800714]
[   48.800714] but task is already holding lock:
[   48.806559] c5952bd3 (&(&array->lock)->rlock){....}, at: dma_fence_add_callback+0x30/0x23c
[   48.814862]
[   48.814862] other info that might help us debug this:
[   48.821410]  Possible unsafe locking scenario:
[   48.821410]
[   48.827338]        CPU0
[   48.829788]        ----
[   48.832239]   lock(&(&array->lock)->rlock);
[   48.836434]   lock(&(&array->lock)->rlock);
[   48.840640]
[   48.840640]  *** DEADLOCK ***
[   48.840640]
[   48.846582]  May be due to missing lock nesting notation
[  130.763560] 1 lock held by cts-runner/3270:
[  130.767745]  #0: 7834b793 (&(&array->lock)->rlock){-...}, at: dma_fence_add_callback+0x30/0x23c
[  130.776461]
               stack backtrace:
[  130.780825] CPU: 1 PID: 3270 Comm: cts-runner Not tainted 4.19.0-rc6+ #486
[  130.787706] Hardware name: Broadcom STB (Flattened Device Tree)
[  130.793645] [<c021269c>] (unwind_backtrace) from [<c020db1c>] (show_stack+0x10/0x14)
[  130.801404] [<c020db1c>] (show_stack) from [<c0c2c4b0>] (dump_stack+0xa8/0xd4)
[  130.808642] [<c0c2c4b0>] (dump_stack) from [<c0281a84>] (__lock_acquire+0x848/0x1a68)
[  130.816483] [<c0281a84>] (__lock_acquire) from [<c02835d8>] (lock_acquire+0xd8/0x22c)
[  130.824326] [<c02835d8>] (lock_acquire) from [<c0c49948>] (_raw_spin_lock_irqsave+0x54/0x68)
[  130.832777] [<c0c49948>] (_raw_spin_lock_irqsave) from [<c086bf54>] (dma_fence_add_callback+0x30/0x23c)
[  130.842183] [<c086bf54>] (dma_fence_add_callback) from [<c086d4c8>] (dma_fence_array_enable_signaling+0x58/0xec)
[  130.852371] [<c086d4c8>] (dma_fence_array_enable_signaling) from [<c086c00c>] (dma_fence_add_callback+0xe8/0x23c)
[  130.862647] [<c086c00c>] (dma_fence_add_callback) from [<c06d8774>] (drm_syncobj_wait_ioctl+0x518/0x614)
[  130.872143] [<c06d8774>] (drm_syncobj_wait_ioctl) from [<c06b8458>] (drm_ioctl_kernel+0xb0/0xf0)
[  130.880940] [<c06b8458>] (drm_ioctl_kernel) from [<c06b8818>] (drm_ioctl+0x1d8/0x390)
[  130.888782] [<c06b8818>] (drm_ioctl) from [<c03a4510>] (do_vfs_ioctl+0xb0/0x8ac)
[  130.896187] [<c03a4510>] (do_vfs_ioctl) from [<c03a4d40>] (ksys_ioctl+0x34/0x60)
[  130.903593] [<c03a4d40>] (ksys_ioctl) from [<c0201000>] (ret_fast_syscall+0x0/0x28)

Cc: Chunming Zhou <david1.zhou@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/261044/

1 files changed, 71 insertions, 288 deletions

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index da2b85eec6cf..90e0a6dce086 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -56,9 +56,6 @@
 #include "drm_internal.h"
 #include <drm/drm_syncobj.h>
 
-/* merge normal syncobj to timeline syncobj, the point interval is 1 */
-#define DRM_SYNCOBJ_BINARY_POINT 1
-
 struct drm_syncobj_stub_fence {
         struct dma_fence base;
         spinlock_t lock;
@@ -74,29 +71,7 @@ static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
         .get_timeline_name = drm_syncobj_stub_fence_get_name,
 };
 
-struct drm_syncobj_signal_pt {
-        struct dma_fence_array *fence_array;
-        u64    value;
-        struct list_head list;
-};
-
-static DEFINE_SPINLOCK(signaled_fence_lock);
-static struct dma_fence signaled_fence;
 
-static struct dma_fence *drm_syncobj_get_stub_fence(void)
-{
-        spin_lock(&signaled_fence_lock);
-        if (!signaled_fence.ops) {
-                dma_fence_init(&signaled_fence,
-                               &drm_syncobj_stub_fence_ops,
-                               &signaled_fence_lock,
-                               0, 0);
-                dma_fence_signal_locked(&signaled_fence);
-        }
-        spin_unlock(&signaled_fence_lock);
-
-        return dma_fence_get(&signaled_fence);
-}
 /**
  * drm_syncobj_find - lookup and reference a sync object.
  * @file_private: drm file private pointer
@@ -123,27 +98,6 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
 }
 EXPORT_SYMBOL(drm_syncobj_find);
 
-static struct dma_fence *
-drm_syncobj_find_signal_pt_for_point(struct drm_syncobj *syncobj,
-                                     uint64_t point)
-{
-        struct drm_syncobj_signal_pt *signal_pt;
-
-        if ((syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) &&
-            (point <= syncobj->timeline))
-                return drm_syncobj_get_stub_fence();
-
-        list_for_each_entry(signal_pt, &syncobj->signal_pt_list, list) {
-                if (point > signal_pt->value)
-                        continue;
-                if ((syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) &&
-                    (point != signal_pt->value))
-                        continue;
-                return dma_fence_get(&signal_pt->fence_array->base);
-        }
-        return NULL;
-}
-
 static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,
                                             struct drm_syncobj_cb *cb,
                                             drm_syncobj_func_t func)
@@ -152,158 +106,53 @@ static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,
         list_add_tail(&cb->node, &syncobj->cb_list);
 }
 
-static void drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj,
-                                                  struct dma_fence **fence,
-                                                  struct drm_syncobj_cb *cb,
-                                                  drm_syncobj_func_t func)
+static int drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj,
+                                                 struct dma_fence **fence,
+                                                 struct drm_syncobj_cb *cb,
+                                                 drm_syncobj_func_t func)
 {
-        u64 pt_value = 0;
-
-        WARN_ON(*fence);
+        int ret;
 
-        if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) {
-                /*BINARY syncobj always wait on last pt */
-                pt_value = syncobj->signal_point;
+        *fence = drm_syncobj_fence_get(syncobj);
+        if (*fence)
+                return 1;
 
-                if (pt_value == 0)
-                        pt_value += DRM_SYNCOBJ_BINARY_POINT;
-        }
-
-        mutex_lock(&syncobj->cb_mutex);
-        spin_lock(&syncobj->pt_lock);
-        *fence = drm_syncobj_find_signal_pt_for_point(syncobj, pt_value);
-        spin_unlock(&syncobj->pt_lock);
-        if (!*fence)
+        spin_lock(&syncobj->lock);
+        /* We've already tried once to get a fence and failed.  Now that we
+         * have the lock, try one more time just to be sure we don't add a
+         * callback when a fence has already been set.
+         */
+        if (syncobj->fence) {
+                *fence = dma_fence_get(rcu_dereference_protected(syncobj->fence,
+                                                                 lockdep_is_held(&syncobj->lock)));
+                ret = 1;
+        } else {
+                *fence = NULL;
                 drm_syncobj_add_callback_locked(syncobj, cb, func);
-        mutex_unlock(&syncobj->cb_mutex);
-}
-
-static void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
-                                        struct drm_syncobj_cb *cb)
-{
-        mutex_lock(&syncobj->cb_mutex);
-        list_del_init(&cb->node);
-        mutex_unlock(&syncobj->cb_mutex);
-}
+                ret = 0;
+        }
+        spin_unlock(&syncobj->lock);
 
-static void drm_syncobj_init(struct drm_syncobj *syncobj)
-{
-        spin_lock(&syncobj->pt_lock);
-        syncobj->timeline_context = dma_fence_context_alloc(1);
-        syncobj->timeline = 0;
-        syncobj->signal_point = 0;
-        init_waitqueue_head(&syncobj->wq);
-
-        INIT_LIST_HEAD(&syncobj->signal_pt_list);
-        spin_unlock(&syncobj->pt_lock);
+        return ret;
 }
 
-static void drm_syncobj_fini(struct drm_syncobj *syncobj)
+void drm_syncobj_add_callback(struct drm_syncobj *syncobj,
+                              struct drm_syncobj_cb *cb,
+                              drm_syncobj_func_t func)
 {
-        struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;
-
-        spin_lock(&syncobj->pt_lock);
-        list_for_each_entry_safe(signal_pt, tmp,
-                                 &syncobj->signal_pt_list, list) {
-                list_del(&signal_pt->list);
-                dma_fence_put(&signal_pt->fence_array->base);
-                kfree(signal_pt);
-        }
-        spin_unlock(&syncobj->pt_lock);
+        spin_lock(&syncobj->lock);
+        drm_syncobj_add_callback_locked(syncobj, cb, func);
+        spin_unlock(&syncobj->lock);
 }
 
-static int drm_syncobj_create_signal_pt(struct drm_syncobj *syncobj,
-                                        struct dma_fence *fence,
-                                        u64 point)
+void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
+                                 struct drm_syncobj_cb *cb)
 {
-        struct drm_syncobj_signal_pt *signal_pt =
-                kzalloc(sizeof(struct drm_syncobj_signal_pt), GFP_KERNEL);
-        struct drm_syncobj_signal_pt *tail_pt;
-        struct dma_fence **fences;
-        int num_fences = 0;
-        int ret = 0, i;
-
-        if (!signal_pt)
-                return -ENOMEM;
-        if (!fence)
-                goto out;
-
-        fences = kmalloc_array(sizeof(void *), 2, GFP_KERNEL);
-        if (!fences) {
-                ret = -ENOMEM;
-                goto out;
-        }
-        fences[num_fences++] = dma_fence_get(fence);
-        /* timeline syncobj must take this dependency */
-        if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
-                spin_lock(&syncobj->pt_lock);
-                if (!list_empty(&syncobj->signal_pt_list)) {
-                        tail_pt = list_last_entry(&syncobj->signal_pt_list,
-                                                  struct drm_syncobj_signal_pt, list);
-                        fences[num_fences++] =
-                                dma_fence_get(&tail_pt->fence_array->base);
-                }
-                spin_unlock(&syncobj->pt_lock);
-        }
-        signal_pt->fence_array = dma_fence_array_create(num_fences, fences,
-                                                        syncobj->timeline_context,
-                                                        point, false);
-        if (!signal_pt->fence_array) {
-                ret = -ENOMEM;
-                goto fail;
-        }
-
-        spin_lock(&syncobj->pt_lock);
-        if (syncobj->signal_point >= point) {
-                DRM_WARN("A later signal is ready!");
-                spin_unlock(&syncobj->pt_lock);
-                goto exist;
-        }
-        signal_pt->value = point;
-        list_add_tail(&signal_pt->list, &syncobj->signal_pt_list);
-        syncobj->signal_point = point;
-        spin_unlock(&syncobj->pt_lock);
-        wake_up_all(&syncobj->wq);
-
-        return 0;
-exist:
-        dma_fence_put(&signal_pt->fence_array->base);
-fail:
-        for (i = 0; i < num_fences; i++)
-                dma_fence_put(fences[i]);
-        kfree(fences);
-out:
-        kfree(signal_pt);
-        return ret;
+        spin_lock(&syncobj->lock);
+        list_del_init(&cb->node);
+        spin_unlock(&syncobj->lock);
 }
 
-static void drm_syncobj_garbage_collection(struct drm_syncobj *syncobj)
-{
-        struct drm_syncobj_signal_pt *signal_pt, *tmp, *tail_pt;
-
-        spin_lock(&syncobj->pt_lock);
-        tail_pt = list_last_entry(&syncobj->signal_pt_list,
-                                  struct drm_syncobj_signal_pt,
-                                  list);
-        list_for_each_entry_safe(signal_pt, tmp,
-                                 &syncobj->signal_pt_list, list) {
-                if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY &&
-                    signal_pt == tail_pt)
-                        continue;
-                if (dma_fence_is_signaled(&signal_pt->fence_array->base)) {
-                        syncobj->timeline = signal_pt->value;
-                        list_del(&signal_pt->list);
-                        dma_fence_put(&signal_pt->fence_array->base);
-                        kfree(signal_pt);
-                } else {
-                        /*signal_pt is in order in list, from small to big, so
-                         * the later must not be signal either */
-                        break;
-                }
-        }
-
-        spin_unlock(&syncobj->pt_lock);
-}
 /**
  * drm_syncobj_replace_fence - replace fence in a sync object.
  * @syncobj: Sync object to replace fence in
@@ -316,30 +165,28 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
                                u64 point,
                                struct dma_fence *fence)
 {
-        u64 pt_value = point;
-
-        drm_syncobj_garbage_collection(syncobj);
-        if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) {
-                if (!fence) {
-                        drm_syncobj_fini(syncobj);
-                        drm_syncobj_init(syncobj);
-                        return;
-                }
-                pt_value = syncobj->signal_point +
-                        DRM_SYNCOBJ_BINARY_POINT;
-        }
-        drm_syncobj_create_signal_pt(syncobj, fence, pt_value);
-        if (fence) {
-                struct drm_syncobj_cb *cur, *tmp;
-                LIST_HEAD(cb_list);
+        struct dma_fence *old_fence;
+        struct drm_syncobj_cb *cur, *tmp;
+
+        if (fence)
+                dma_fence_get(fence);
+
+        spin_lock(&syncobj->lock);
+
+        old_fence = rcu_dereference_protected(syncobj->fence,
+                                              lockdep_is_held(&syncobj->lock));
+        rcu_assign_pointer(syncobj->fence, fence);
 
-                mutex_lock(&syncobj->cb_mutex);
+        if (fence != old_fence) {
                 list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node) {
                         list_del_init(&cur->node);
                         cur->func(syncobj, cur);
                 }
-                mutex_unlock(&syncobj->cb_mutex);
         }
+
+        spin_unlock(&syncobj->lock);
+
+        dma_fence_put(old_fence);
 }
 EXPORT_SYMBOL(drm_syncobj_replace_fence);
 
@@ -362,64 +209,6 @@ static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
         return 0;
 }
 
-static int
-drm_syncobj_point_get(struct drm_syncobj *syncobj, u64 point, u64 flags,
-                      struct dma_fence **fence)
-{
-        int ret = 0;
-
-        if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
-                ret = wait_event_interruptible(syncobj->wq,
-                                               point <= syncobj->signal_point);
-                if (ret < 0)
-                        return ret;
-        }
-        spin_lock(&syncobj->pt_lock);
-        *fence = drm_syncobj_find_signal_pt_for_point(syncobj, point);
-        if (!*fence)
-                ret = -EINVAL;
-        spin_unlock(&syncobj->pt_lock);
-        return ret;
-}
-
-/**
- * drm_syncobj_search_fence - lookup and reference the fence in a sync object or
- * in a timeline point
- * @syncobj: sync object pointer
- * @point: timeline point
- * @flags: DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT or not
- * @fence: out parameter for the fence
- *
- * if flags is DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT, the function will block
- * here until specific timeline points is reached.
- * if not, you need a submit thread and block in userspace until all future
- * timeline points have materialized, only then you can submit to the kernel,
- * otherwise, function will fail to return fence.
- *
- * Returns 0 on success or a negative error value on failure. On success @fence
- * contains a reference to the fence, which must be released by calling
- * dma_fence_put().
- */
-int drm_syncobj_search_fence(struct drm_syncobj *syncobj, u64 point,
-                             u64 flags, struct dma_fence **fence)
-{
-        u64 pt_value = point;
-
-        if (!syncobj)
-                return -ENOENT;
-
-        drm_syncobj_garbage_collection(syncobj);
-        if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) {
-                /*BINARY syncobj always wait on last pt */
-                pt_value = syncobj->signal_point;
-
-                if (pt_value == 0)
-                        pt_value += DRM_SYNCOBJ_BINARY_POINT;
-        }
-        return drm_syncobj_point_get(syncobj, pt_value, flags, fence);
-}
-EXPORT_SYMBOL(drm_syncobj_search_fence);
-
 /**
  * drm_syncobj_find_fence - lookup and reference the fence in a sync object
  * @file_private: drm file private pointer
@@ -429,7 +218,7 @@ EXPORT_SYMBOL(drm_syncobj_search_fence);
  * @fence: out parameter for the fence
  *
  * This is just a convenience function that combines drm_syncobj_find() and
- * drm_syncobj_lookup_fence().
+ * drm_syncobj_fence_get().
  *
  * Returns 0 on success or a negative error value on failure. On success @fence
  * contains a reference to the fence, which must be released by calling
@@ -440,11 +229,16 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
                            struct dma_fence **fence)
 {
         struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
-        int ret;
+        int ret = 0;
 
-        ret = drm_syncobj_search_fence(syncobj, point, flags, fence);
-        if (syncobj)
-                drm_syncobj_put(syncobj);
+        if (!syncobj)
+                return -ENOENT;
+
+        *fence = drm_syncobj_fence_get(syncobj);
+        if (!*fence) {
+                ret = -EINVAL;
+        }
+        drm_syncobj_put(syncobj);
         return ret;
 }
 EXPORT_SYMBOL(drm_syncobj_find_fence);
@@ -460,7 +254,7 @@ void drm_syncobj_free(struct kref *kref)
         struct drm_syncobj *syncobj = container_of(kref,
                                                    struct drm_syncobj,
                                                    refcount);
-        drm_syncobj_fini(syncobj);
+        drm_syncobj_replace_fence(syncobj, 0, NULL);
         kfree(syncobj);
 }
 EXPORT_SYMBOL(drm_syncobj_free);
@@ -493,13 +287,7 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
 
         kref_init(&syncobj->refcount);
         INIT_LIST_HEAD(&syncobj->cb_list);
-        spin_lock_init(&syncobj->pt_lock);
-        mutex_init(&syncobj->cb_mutex);
-        if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE)
-                syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE;
-        else
-                syncobj->type = DRM_SYNCOBJ_TYPE_BINARY;
-        drm_syncobj_init(syncobj);
+        spin_lock_init(&syncobj->lock);
 
         if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
                 ret = drm_syncobj_assign_null_handle(syncobj);
@@ -782,8 +570,7 @@ drm_syncobj_create_ioctl(struct drm_device *dev, void *data,
                 return -EOPNOTSUPP;
 
         /* no valid flags yet */
-        if (args->flags & ~(DRM_SYNCOBJ_CREATE_SIGNALED |
-                            DRM_SYNCOBJ_CREATE_TYPE_TIMELINE))
+        if (args->flags & ~DRM_SYNCOBJ_CREATE_SIGNALED)
                 return -EINVAL;
 
         return drm_syncobj_create_as_handle(file_private,
@@ -876,8 +663,9 @@ static void syncobj_wait_syncobj_func(struct drm_syncobj *syncobj,
         struct syncobj_wait_entry *wait =
                 container_of(cb, struct syncobj_wait_entry, syncobj_cb);
 
-        drm_syncobj_search_fence(syncobj, 0, 0, &wait->fence);
-
+        /* This happens inside the syncobj lock */
+        wait->fence = dma_fence_get(rcu_dereference_protected(syncobj->fence,
+                                                              lockdep_is_held(&syncobj->lock)));
         wake_up_process(wait->task);
 }
 
@@ -903,8 +691,7 @@ static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
         signaled_count = 0;
         for (i = 0; i < count; ++i) {
                 entries[i].task = current;
-                drm_syncobj_search_fence(syncobjs[i], 0, 0,
-                                         &entries[i].fence);
+                entries[i].fence = drm_syncobj_fence_get(syncobjs[i]);
                 if (!entries[i].fence) {
                         if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
                                 continue;
@@ -935,9 +722,6 @@ static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
 
         if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
                 for (i = 0; i < count; ++i) {
-                        if (entries[i].fence)
-                                continue;
-
                         drm_syncobj_fence_get_or_add_callback(syncobjs[i],
                                                               &entries[i].fence,
                                                               &entries[i].syncobj_cb,
@@ -1169,13 +953,12 @@ drm_syncobj_reset_ioctl(struct drm_device *dev, void *data,
         if (ret < 0)
                 return ret;
 
-        for (i = 0; i < args->count_handles; i++) {
-                drm_syncobj_fini(syncobjs[i]);
-                drm_syncobj_init(syncobjs[i]);
-        }
+        for (i = 0; i < args->count_handles; i++)
+                drm_syncobj_replace_fence(syncobjs[i], 0, NULL);
+
         drm_syncobj_array_free(syncobjs, args->count_handles);
 
-        return ret;
+        return 0;
 }
 
 int