openwrt/target/linux/brcm2708/patches-4.19/950-0689-Revert-media-vb2-Allow-reqbufs-0-with-in-use-MMAP-bu.patch

From 768ab361410487b05561de854a994a2888cd430a Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.org>
Date: Fri, 28 Jun 2019 11:30:49 +0100
Subject: [PATCH 689/806] Revert "media: vb2: Allow reqbufs(0) with "in use"
 MMAP buffers"

This reverts commit a2c73e18c1f657de6d654f51effa0a94863abbd8.
An alternative version was accepted upstream. Revert this patch to
apply that one.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
---
 .../media/common/videobuf2/videobuf2-core.c   | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -554,6 +554,20 @@ bool vb2_buffer_in_use(struct vb2_queue
 }
 EXPORT_SYMBOL(vb2_buffer_in_use);
 
+/*
+ * __buffers_in_use() - return true if any buffers on the queue are in use and
+ * the queue cannot be freed (by the means of REQBUFS(0)) call
+ */
+static bool __buffers_in_use(struct vb2_queue *q)
+{
+	unsigned int buffer;
+	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
+		if (vb2_buffer_in_use(q, q->bufs[buffer]))
+			return true;
+	}
+	return false;
+}
+
 void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb)
 {
 	call_void_bufop(q, fill_user_buffer, q->bufs[index], pb);
@@ -665,7 +679,16 @@ int vb2_core_reqbufs(struct vb2_queue *q
 
 	if (*count == 0 || q->num_buffers != 0 ||
 	    (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory)) {
+		/*
+		 * We already have buffers allocated, so first check if they
+		 * are not in use and can be freed.
+		 */
 		mutex_lock(&q->mmap_lock);
+		if (q->memory == VB2_MEMORY_MMAP && __buffers_in_use(q)) {
+			mutex_unlock(&q->mmap_lock);
+			dprintk(1, "memory in use, cannot free\n");
+			return -EBUSY;
+		}
 
 		/*
 		 * Call queue_cancel to clean up any buffers in the PREPARED or