Revert 190c462d5be19ba622a82f5fd0625087c870a1e6..bf3012ada1b2222e770de5c35c1bb16f73b3a01d"

I shouldn't have pushed this, CI was right - I failed to remove the
BUG_ON(!ops->wait);

Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

8 files changed, 54 insertions, 29 deletions

diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
index a8c254497251..dd1edfb27b61 100644
--- a/drivers/dma-buf/dma-fence-array.c
+++ b/drivers/dma-buf/dma-fence-array.c
@@ -104,6 +104,7 @@ const struct dma_fence_ops dma_fence_array_ops = {
         .get_timeline_name = dma_fence_array_get_timeline_name,
         .enable_signaling = dma_fence_array_enable_signaling,
         .signaled = dma_fence_array_signaled,
+        .wait = dma_fence_default_wait,
         .release = dma_fence_array_release,
 };
 EXPORT_SYMBOL(dma_fence_array_ops);
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 30fcbe415ff4..4edb9fd3cf47 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -158,10 +158,7 @@ dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
                 return -EINVAL;
 
         trace_dma_fence_wait_start(fence);
-        if (fence->ops->wait)
-                ret = fence->ops->wait(fence, intr, timeout);
-        else
-                ret = dma_fence_default_wait(fence, intr, timeout);
+        ret = fence->ops->wait(fence, intr, timeout);
         trace_dma_fence_wait_end(fence);
         return ret;
 }
@@ -184,13 +181,6 @@ void dma_fence_release(struct kref *kref)
 }
 EXPORT_SYMBOL(dma_fence_release);
 
-/**
- * dma_fence_free - default release function for &dma_fence.
- * @fence: fence to release
- *
- * This is the default implementation for &dma_fence_ops.release. It calls
- * kfree_rcu() on @fence.
- */
 void dma_fence_free(struct dma_fence *fence)
 {
         kfree_rcu(fence, rcu);
@@ -506,6 +496,11 @@ dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
         for (i = 0; i < count; ++i) {
                 struct dma_fence *fence = fences[i];
 
+                if (fence->ops->wait != dma_fence_default_wait) {
+                        ret = -EINVAL;
+                        goto fence_rm_cb;
+                }
+
                 cb[i].task = current;
                 if (dma_fence_add_callback(fence, &cb[i].base,
                                            dma_fence_default_wait_cb)) {
@@ -565,7 +560,7 @@ dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
                spinlock_t *lock, u64 context, unsigned seqno)
 {
         BUG_ON(!lock);
-        BUG_ON(!ops || !ops->wait ||
+        BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
                !ops->get_driver_name || !ops->get_timeline_name);
 
         kref_init(&fence->refcount);
@@ -577,10 +572,6 @@ dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
         fence->flags = 0UL;
         fence->error = 0;
 
-        if (!ops->enable_signaling)
-                set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
-                        &fence->flags);
-
         trace_dma_fence_init(fence);
 }
 EXPORT_SYMBOL(dma_fence_init);
diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c
index 53c1d6d36a64..3d78ca89a605 100644
--- a/drivers/dma-buf/sw_sync.c
+++ b/drivers/dma-buf/sw_sync.c
@@ -188,6 +188,7 @@ static const struct dma_fence_ops timeline_fence_ops = {
         .get_timeline_name = timeline_fence_get_timeline_name,
         .enable_signaling = timeline_fence_enable_signaling,
         .signaled = timeline_fence_signaled,
+        .wait = dma_fence_default_wait,
         .release = timeline_fence_release,
         .fence_value_str = timeline_fence_value_str,
         .timeline_value_str = timeline_fence_timeline_value_str,
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index e4d3285f4191..a231dd5dce16 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -225,9 +225,16 @@ static const char *drm_crtc_fence_get_timeline_name(struct dma_fence *fence)
         return crtc->timeline_name;
 }
 
+static bool drm_crtc_fence_enable_signaling(struct dma_fence *fence)
+{
+        return true;
+}
+
 static const struct dma_fence_ops drm_crtc_fence_ops = {
         .get_driver_name = drm_crtc_fence_get_driver_name,
         .get_timeline_name = drm_crtc_fence_get_timeline_name,
+        .enable_signaling = drm_crtc_fence_enable_signaling,
+        .wait = dma_fence_default_wait,
 };
 
 struct dma_fence *drm_crtc_create_fence(struct drm_crtc *crtc)
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index adb3cb27d31e..d4f4ce484529 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -207,6 +207,7 @@ static const struct dma_fence_ops drm_syncobj_null_fence_ops = {
         .get_driver_name = drm_syncobj_null_fence_get_name,
         .get_timeline_name = drm_syncobj_null_fence_get_name,
         .enable_signaling = drm_syncobj_null_fence_enable_signaling,
+        .wait = dma_fence_default_wait,
         .release = NULL,
 };
 
diff --git a/drivers/gpu/drm/qxl/qxl_release.c b/drivers/gpu/drm/qxl/qxl_release.c
index 04f3605ac42a..5d84a66fed36 100644
--- a/drivers/gpu/drm/qxl/qxl_release.c
+++ b/drivers/gpu/drm/qxl/qxl_release.c
@@ -50,6 +50,12 @@ static const char *qxl_get_timeline_name(struct dma_fence *fence)
         return "release";
 }
 
+static bool qxl_nop_signaling(struct dma_fence *fence)
+{
+        /* fences are always automatically signaled, so just pretend we did this.. */
+        return true;
+}
+
 static long qxl_fence_wait(struct dma_fence *fence, bool intr,
                            signed long timeout)
 {
@@ -113,6 +119,7 @@ signaled:
 static const struct dma_fence_ops qxl_fence_ops = {
         .get_driver_name = qxl_get_driver_name,
         .get_timeline_name = qxl_get_timeline_name,
+        .enable_signaling = qxl_nop_signaling,
         .wait = qxl_fence_wait,
 };
 
diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c
index 4843289cc8f0..69aab086b913 100644
--- a/drivers/gpu/drm/scheduler/sched_fence.c
+++ b/drivers/gpu/drm/scheduler/sched_fence.c
@@ -81,6 +81,11 @@ static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f)
         return (const char *)fence->sched->name;
 }
 
+static bool drm_sched_fence_enable_signaling(struct dma_fence *f)
+{
+        return true;
+}
+
 /**
  * amd_sched_fence_free - free up the fence memory
  *
@@ -129,12 +134,18 @@ static void drm_sched_fence_release_finished(struct dma_fence *f)
 const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
         .get_driver_name = drm_sched_fence_get_driver_name,
         .get_timeline_name = drm_sched_fence_get_timeline_name,
+        .enable_signaling = drm_sched_fence_enable_signaling,
+        .signaled = NULL,
+        .wait = dma_fence_default_wait,
         .release = drm_sched_fence_release_scheduled,
 };
 
 const struct dma_fence_ops drm_sched_fence_ops_finished = {
         .get_driver_name = drm_sched_fence_get_driver_name,
         .get_timeline_name = drm_sched_fence_get_timeline_name,
+        .enable_signaling = drm_sched_fence_enable_signaling,
+        .signaled = NULL,
+        .wait = dma_fence_default_wait,
         .release = drm_sched_fence_release_finished,
 };
 
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 02dba8cd033d..eb9b05aa5aea 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -166,8 +166,7 @@ struct dma_fence_ops {
          * released when the fence is signalled (through e.g. the interrupt
          * handler).
          *
-         * This callback is optional. If this callback is not present, then the
-         * driver must always have signaling enabled.
+         * This callback is mandatory.
          */
         bool (*enable_signaling)(struct dma_fence *fence);
 
@@ -191,14 +190,11 @@ struct dma_fence_ops {
         /**
          * @wait:
          *
-         * Custom wait implementation, defaults to dma_fence_default_wait() if
-         * not set.
+         * Custom wait implementation, or dma_fence_default_wait.
          *
-         * The dma_fence_default_wait implementation should work for any fence, as long
-         * as @enable_signaling works correctly. This hook allows drivers to
-         * have an optimized version for the case where a process context is
-         * already available, e.g. if @enable_signaling for the general case
-         * needs to set up a worker thread.
+         * Must not be NULL, set to dma_fence_default_wait for default implementation.
+         * the dma_fence_default_wait implementation should work for any fence, as long
+         * as enable_signaling works correctly.
          *
          * Must return -ERESTARTSYS if the wait is intr = true and the wait was
          * interrupted, and remaining jiffies if fence has signaled, or 0 if wait
@@ -206,7 +202,7 @@ struct dma_fence_ops {
          * which should be treated as if the fence is signaled. For example a hardware
          * lockup could be reported like that.
          *
-         * This callback is optional.
+         * This callback is mandatory.
          */
         signed long (*wait)(struct dma_fence *fence,
                             bool intr, signed long timeout);
@@ -222,6 +218,17 @@ struct dma_fence_ops {
         void (*release)(struct dma_fence *fence);
 
         /**
+         * @fill_driver_data:
+         *
+         * Callback to fill in free-form debug info.
+         *
+         * Returns amount of bytes filled, or negative error on failure.
+         *
+         * This callback is optional.
+         */
+        int (*fill_driver_data)(struct dma_fence *fence, void *data, int size);
+
+        /**
          * @fence_value_str:
          *
          * Callback to fill in free-form debug info specific to this fence, like
@@ -235,9 +242,8 @@ struct dma_fence_ops {
          * @timeline_value_str:
          *
          * Fills in the current value of the timeline as a string, like the
-         * sequence number. Note that the specific fence passed to this function
-         * should not matter, drivers should only use it to look up the
-         * corresponding timeline structures.
+         * sequence number. This should match what @fill_driver_data prints for
+         * the most recently signalled fence (assuming no delayed signalling).
          */
         void (*timeline_value_str)(struct dma_fence *fence,
                                    char *str, int size);