1 files changed, 27 insertions, 54 deletions

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 2ea59cb8edcd..6437b2e978fb 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -67,12 +67,9 @@ static void dma_buf_release(struct dentry *dentry)
 	BUG_ON(dmabuf->vmapping_counter);
 
 	/*
-	 * Any fences that a dma-buf poll can wait on should be signaled
-	 * before releasing dma-buf. This is the responsibility of each
-	 * driver that uses the reservation objects.
-	 *
-	 * If you hit this BUG() it means someone dropped their ref to the
-	 * dma-buf while still having pending operation to the buffer.
+	 * If you hit this BUG() it could mean:
+	 * * There's a file reference imbalance in dma_buf_poll / dma_buf_poll_cb or somewhere else
+	 * * dmabuf->cb_in/out.active are non-0 despite no pending fence callback
 	 */
 	BUG_ON(dmabuf->cb_in.active || dmabuf->cb_out.active);
 
@@ -200,6 +197,7 @@ static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
 static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 {
 	struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;
+	struct dma_buf *dmabuf = container_of(dcb->poll, struct dma_buf, poll);
 	unsigned long flags;
 
 	spin_lock_irqsave(&dcb->poll->lock, flags);
@@ -207,21 +205,18 @@ static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 	dcb->active = 0;
 	spin_unlock_irqrestore(&dcb->poll->lock, flags);
 	dma_fence_put(fence);
+	/* Paired with get_file in dma_buf_poll */
+	fput(dmabuf->file);
 }
 
-static bool dma_buf_poll_shared(struct dma_resv *resv,
+static bool dma_buf_poll_add_cb(struct dma_resv *resv, bool write,
 				struct dma_buf_poll_cb_t *dcb)
 {
-	struct dma_resv_list *fobj = dma_resv_shared_list(resv);
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
-	int i, r;
-
-	if (!fobj)
-		return false;
+	int r;
 
-	for (i = 0; i < fobj->shared_count; ++i) {
-		fence = rcu_dereference_protected(fobj->shared[i],
-						  dma_resv_held(resv));
+	dma_resv_for_each_fence(&cursor, resv, write, fence) {
 		dma_fence_get(fence);
 		r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);
 		if (!r)
@@ -232,24 +227,6 @@ static bool dma_buf_poll_shared(struct dma_resv *resv,
 	return false;
 }
 
-static bool dma_buf_poll_excl(struct dma_resv *resv,
-			      struct dma_buf_poll_cb_t *dcb)
-{
-	struct dma_fence *fence = dma_resv_excl_fence(resv);
-	int r;
-
-	if (!fence)
-		return false;
-
-	dma_fence_get(fence);
-	r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);
-	if (!r)
-		return true;
-	dma_fence_put(fence);
-
-	return false;
-}
-
 static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
 {
 	struct dma_buf *dmabuf;
@@ -282,8 +259,10 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
 		spin_unlock_irq(&dmabuf->poll.lock);
 
 		if (events & EPOLLOUT) {
-			if (!dma_buf_poll_shared(resv, dcb) &&
-			    !dma_buf_poll_excl(resv, dcb))
+			/* Paired with fput in dma_buf_poll_cb */
+			get_file(dmabuf->file);
+
+			if (!dma_buf_poll_add_cb(resv, true, dcb))
 				/* No callback queued, wake up any other waiters */
 				dma_buf_poll_cb(NULL, &dcb->cb);
 			else
@@ -303,7 +282,10 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
 		spin_unlock_irq(&dmabuf->poll.lock);
 
 		if (events & EPOLLIN) {
-			if (!dma_buf_poll_excl(resv, dcb))
+			/* Paired with fput in dma_buf_poll_cb */
+			get_file(dmabuf->file);
+
+			if (!dma_buf_poll_add_cb(resv, false, dcb))
 				/* No callback queued, wake up any other waiters */
 				dma_buf_poll_cb(NULL, &dcb->cb);
 			else
@@ -1356,10 +1338,9 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 {
 	struct dma_buf *buf_obj;
 	struct dma_buf_attachment *attach_obj;
-	struct dma_resv *robj;
-	struct dma_resv_list *fobj;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
-	int count = 0, attach_count, shared_count, i;
+	int count = 0, attach_count;
 	size_t size = 0;
 	int ret;
 
@@ -1378,6 +1359,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 		if (ret)
 			goto error_unlock;
 
+
+		spin_lock(&buf_obj->name_lock);
 		seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
 				buf_obj->size,
 				buf_obj->file->f_flags, buf_obj->file->f_mode,
@@ -1385,22 +1368,12 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 				buf_obj->exp_name,
 				file_inode(buf_obj->file)->i_ino,
 				buf_obj->name ?: "");
+		spin_unlock(&buf_obj->name_lock);
 
-		robj = buf_obj->resv;
-		fence = dma_resv_excl_fence(robj);
-		if (fence)
-			seq_printf(s, "\tExclusive fence: %s %s %ssignalled\n",
-				   fence->ops->get_driver_name(fence),
-				   fence->ops->get_timeline_name(fence),
-				   dma_fence_is_signaled(fence) ? "" : "un");
-
-		fobj = rcu_dereference_protected(robj->fence,
-						 dma_resv_held(robj));
-		shared_count = fobj ? fobj->shared_count : 0;
-		for (i = 0; i < shared_count; i++) {
-			fence = rcu_dereference_protected(fobj->shared[i],
-							  dma_resv_held(robj));
-			seq_printf(s, "\tShared fence: %s %s %ssignalled\n",
+		dma_resv_for_each_fence(&cursor, buf_obj->resv, true, fence) {
+			seq_printf(s, "\t%s fence: %s %s %ssignalled\n",
+				   dma_resv_iter_is_exclusive(&cursor) ?
+					"Exclusive" : "Shared",
 				   fence->ops->get_driver_name(fence),
 				   fence->ops->get_timeline_name(fence),
 				   dma_fence_is_signaled(fence) ? "" : "un");