dma-fence: Propagate errors to dma-fence-array container

When one of the array of fences is signaled, propagate its errors to the
parent fence-array (keeping the first error to be raised).

v2: Opencode cmpxchg_local to avoid compiler freakout.
v3: Be careful not to flag an error if we race against signal-on-any.
v4: Same applies to installing the signal cb.
v5: Use cmpxchg to only set the error once before using a nifty idea by
Christian to avoid changing the status after emitting the signal.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Christian König <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190811210902.22112-1-chris@chris-wilson.co.uk

diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
index 12c6f64c0bc272f03be1cf9bd5f39676ca66f533..d3fbd950be944f7a3bc7c2d231a0573cea5eac70 100644 (file)
--- a/drivers/dma-buf/dma-fence-array.c
+++ b/drivers/dma-buf/dma-fence-array.c
@@ -13,6 +13,8 @@
 #include <linux/slab.h>
 #include <linux/dma-fence-array.h>
 
+#define PENDING_ERROR 1
+
 static const char *dma_fence_array_get_driver_name(struct dma_fence *fence)
 {
        return "dma_fence_array";
@@ -23,10 +25,29 @@ static const char *dma_fence_array_get_timeline_name(struct dma_fence *fence)
        return "unbound";
 }
 
+static void dma_fence_array_set_pending_error(struct dma_fence_array *array,
+                                             int error)
+{
+       /*
+        * Propagate the first error reported by any of our fences, but only
+        * before we ourselves are signaled.
+        */
+       if (error)
+               cmpxchg(&array->base.error, PENDING_ERROR, error);
+}
+
+static void dma_fence_array_clear_pending_error(struct dma_fence_array *array)
+{
+       /* Clear the error flag if not actually set. */
+       cmpxchg(&array->base.error, PENDING_ERROR, 0);
+}
+
 static void irq_dma_fence_array_work(struct irq_work *wrk)
 {
        struct dma_fence_array *array = container_of(wrk, typeof(*array), work);
 
+       dma_fence_array_clear_pending_error(array);
+
        dma_fence_signal(&array->base);
        dma_fence_put(&array->base);
 }
@@ -38,6 +59,8 @@ static void dma_fence_array_cb_func(struct dma_fence *f,
                container_of(cb, struct dma_fence_array_cb, cb);
        struct dma_fence_array *array = array_cb->array;
 
+       dma_fence_array_set_pending_error(array, f->error);
+
        if (atomic_dec_and_test(&array->num_pending))
                irq_work_queue(&array->work);
        else
@@ -63,9 +86,14 @@ static bool dma_fence_array_enable_signaling(struct dma_fence *fence)
                dma_fence_get(&array->base);
                if (dma_fence_add_callback(array->fences[i], &cb[i].cb,
                                           dma_fence_array_cb_func)) {
+                       int error = array->fences[i]->error;
+
+                       dma_fence_array_set_pending_error(array, error);
                        dma_fence_put(&array->base);
-                       if (atomic_dec_and_test(&array->num_pending))
+                       if (atomic_dec_and_test(&array->num_pending)) {
+                               dma_fence_array_clear_pending_error(array);
                                return false;
+                       }
                }
        }
 
@@ -142,6 +170,8 @@ struct dma_fence_array *dma_fence_array_create(int num_fences,
        atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
        array->fences = fences;
 
+       array->base.error = PENDING_ERROR;
+
        return array;
 }
 EXPORT_SYMBOL(dma_fence_array_create);