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Subject[PATCH 2/2] drm: Revert syncobj timeline changes.
Date
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>
---
drivers/gpu/drm/drm_syncobj.c | 359 +++++++---------------------------
include/drm/drm_syncobj.h | 73 ++++---
2 files changed, 105 insertions(+), 327 deletions(-)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index da8175d9c6ff..e2c5b3ca4824 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);
-
- if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) {
- /*BINARY syncobj always wait on last pt */
- pt_value = syncobj->signal_point;
+ int ret;

- if (pt_value == 0)
- pt_value += DRM_SYNCOBJ_BINARY_POINT;
- }
+ *fence = drm_syncobj_fence_get(syncobj);
+ if (*fence)
+ return 1;

- 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);

- mutex_lock(&syncobj->cb_mutex);
+ old_fence = rcu_dereference_protected(syncobj->fence,
+ lockdep_is_held(&syncobj->lock));
+ rcu_assign_pointer(syncobj->fence, fence);
+
+ 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);
@@ -489,13 +283,7 @@ 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);
@@ -778,8 +566,7 @@ 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,
@@ -872,8 +659,9 @@ 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);
}

@@ -899,8 +687,7 @@ 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;
@@ -931,9 +718,6 @@ 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,
@@ -1165,13 +949,12 @@ 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
diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
index 29244cbcd05e..2eda44def639 100644
--- a/include/drm/drm_syncobj.h
+++ b/include/drm/drm_syncobj.h
@@ -30,15 +30,10 @@

struct drm_syncobj_cb;

-enum drm_syncobj_type {
- DRM_SYNCOBJ_TYPE_BINARY,
- DRM_SYNCOBJ_TYPE_TIMELINE
-};
-
/**
* struct drm_syncobj - sync object.
*
- * This structure defines a generic sync object which is timeline based.
+ * This structure defines a generic sync object which wraps a &dma_fence.
*/
struct drm_syncobj {
/**
@@ -46,42 +41,21 @@ struct drm_syncobj {
*/
struct kref refcount;
/**
- * @type: indicate syncobj type
- */
- enum drm_syncobj_type type;
- /**
- * @wq: wait signal operation work queue
- */
- wait_queue_head_t wq;
- /**
- * @timeline_context: fence context used by timeline
+ * @fence:
+ * NULL or a pointer to the fence bound to this object.
+ *
+ * This field should not be used directly. Use drm_syncobj_fence_get()
+ * and drm_syncobj_replace_fence() instead.
*/
- u64 timeline_context;
+ struct dma_fence __rcu *fence;
/**
- * @timeline: syncobj timeline value, which indicates point is signaled.
+ * @cb_list: List of callbacks to call when the &fence gets replaced.
*/
- u64 timeline;
- /**
- * @signal_point: which indicates the latest signaler point.
- */
- u64 signal_point;
- /**
- * @signal_pt_list: signaler point list.
- */
- struct list_head signal_pt_list;
-
- /**
- * @cb_list: List of callbacks to call when the &fence gets replaced.
- */
struct list_head cb_list;
/**
- * @pt_lock: Protects pt list.
+ * @lock: Protects &cb_list and write-locks &fence.
*/
- spinlock_t pt_lock;
- /**
- * @cb_mutex: Protects syncobj cb list.
- */
- struct mutex cb_mutex;
+ spinlock_t lock;
/**
* @file: A file backing for this syncobj.
*/
@@ -94,7 +68,7 @@ typedef void (*drm_syncobj_func_t)(struct drm_syncobj *syncobj,
/**
* struct drm_syncobj_cb - callback for drm_syncobj_add_callback
* @node: used by drm_syncob_add_callback to append this struct to
- * &drm_syncobj.cb_list
+ * &drm_syncobj.cb_list
* @func: drm_syncobj_func_t to call
*
* This struct will be initialized by drm_syncobj_add_callback, additional
@@ -132,6 +106,29 @@ drm_syncobj_put(struct drm_syncobj *obj)
kref_put(&obj->refcount, drm_syncobj_free);
}

+/**
+ * drm_syncobj_fence_get - get a reference to a fence in a sync object
+ * @syncobj: sync object.
+ *
+ * This acquires additional reference to &drm_syncobj.fence contained in @obj,
+ * if not NULL. It is illegal to call this without already holding a reference.
+ * No locks required.
+ *
+ * Returns:
+ * Either the fence of @obj or NULL if there's none.
+ */
+static inline struct dma_fence *
+drm_syncobj_fence_get(struct drm_syncobj *syncobj)
+{
+ struct dma_fence *fence;
+
+ rcu_read_lock();
+ fence = dma_fence_get_rcu_safe(&syncobj->fence);
+ rcu_read_unlock();
+
+ return fence;
+}
+
struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
u32 handle);
void drm_syncobj_replace_fence(struct drm_syncobj *syncobj, u64 point,
@@ -145,7 +142,5 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
int drm_syncobj_get_handle(struct drm_file *file_private,
struct drm_syncobj *syncobj, u32 *handle);
int drm_syncobj_get_fd(struct drm_syncobj *syncobj, int *p_fd);
-int drm_syncobj_search_fence(struct drm_syncobj *syncobj, u64 point, u64 flags,
- struct dma_fence **fence);

#endif
--
2.19.1
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