From e6cb5200366a5134ffefb79f0be578237ffe5c95 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wtaymans@redhat.com>
Date: Sun, 15 Mar 2015 17:27:33 +0100
Subject: [PATCH] fdmemory: add flags to control behaviour

Add some flags to the GstFdMemory to control how memory is mapped and
unmapped.
---
 gst-libs/gst/allocators/gstdmabuf.c   |  2 +-
 gst-libs/gst/allocators/gstfdmemory.c | 25 +++++++++++++++++++------
 gst-libs/gst/allocators/gstfdmemory.h | 22 ++++++++++++++++++++--
 3 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/gst-libs/gst/allocators/gstdmabuf.c b/gst-libs/gst/allocators/gstdmabuf.c
index 76bff24707..84e0c7844c 100644
--- a/gst-libs/gst/allocators/gstdmabuf.c
+++ b/gst-libs/gst/allocators/gstdmabuf.c
@@ -120,7 +120,7 @@ gst_dmabuf_allocator_alloc (GstAllocator * allocator, gint fd, gsize size)
   }
 
   GST_DEBUG ("alloc from allocator %p", allocator);
-  return __gst_fd_memory_new (allocator, fd, size);
+  return __gst_fd_memory_new (allocator, fd, size, GST_FD_MEMORY_FLAG_NONE);
 #else /* !HAVE_MMAP */
   return NULL;
 #endif
diff --git a/gst-libs/gst/allocators/gstfdmemory.c b/gst-libs/gst/allocators/gstfdmemory.c
index bdd95fc28e..9a5c5b3ca8 100644
--- a/gst-libs/gst/allocators/gstfdmemory.c
+++ b/gst-libs/gst/allocators/gstfdmemory.c
@@ -36,7 +36,10 @@ gst_fd_mem_free (GstAllocator * allocator, GstMemory * gmem)
   GstFdMemory *mem = (GstFdMemory *) gmem;
 
   if (mem->data) {
-    g_warning (G_STRLOC ":%s: Freeing memory %p still mapped", G_STRFUNC, mem);
+    if (!(mem->flags & GST_FD_MEMORY_FLAG_KEEP_MAPPED))
+      g_warning (G_STRLOC ":%s: Freeing memory %p still mapped", G_STRFUNC,
+          mem);
+
     munmap ((void *) mem->data, gmem->maxsize);
   }
   if (mem->fd >= 0 && gmem->parent == NULL)
@@ -58,11 +61,10 @@ gst_fd_mem_map (GstMemory * gmem, gsize maxsize, GstMapFlags flags)
   if (gmem->parent)
     return gst_fd_mem_map (gmem->parent, maxsize, flags);
 
-  g_mutex_lock (&mem->lock);
-
   prot = flags & GST_MAP_READ ? PROT_READ : 0;
   prot |= flags & GST_MAP_WRITE ? PROT_WRITE : 0;
 
+  g_mutex_lock (&mem->lock);
   /* do not mmap twice the buffer */
   if (mem->data) {
     /* only return address if mapping flags are a subset
@@ -76,7 +78,13 @@ gst_fd_mem_map (GstMemory * gmem, gsize maxsize, GstMapFlags flags)
   }
 
   if (mem->fd != -1) {
-    mem->data = mmap (0, gmem->maxsize, prot, MAP_SHARED, mem->fd, 0);
+    gint flags;
+
+    flags =
+        (mem->flags & GST_FD_MEMORY_FLAG_MAP_PRIVATE) ? MAP_PRIVATE :
+        MAP_SHARED;
+
+    mem->data = mmap (0, gmem->maxsize, prot, flags, mem->fd, 0);
     if (mem->data == MAP_FAILED) {
       mem->data = NULL;
       GST_ERROR ("%p: fd %d: mmap failed: %s", mem, mem->fd,
@@ -110,8 +118,10 @@ gst_fd_mem_unmap (GstMemory * gmem)
   if (gmem->parent)
     return gst_fd_mem_unmap (gmem->parent);
 
-  g_mutex_lock (&mem->lock);
+  if (mem->flags & GST_FD_MEMORY_FLAG_KEEP_MAPPED)
+    return;
 
+  g_mutex_lock (&mem->lock);
   if (mem->data && !(--mem->mmap_count)) {
     munmap ((void *) mem->data, gmem->maxsize);
     mem->data = NULL;
@@ -160,6 +170,7 @@ gst_fd_mem_share (GstMemory * gmem, gssize offset, gssize size)
  * @allocator: allocator to be used for this memory
  * @fd: file descriptor
  * @size: memory size
+ * @flags: extra #GstFdMemoryFlags
  *
  * Return a %GstMemory that wraps a file descriptor.
  *
@@ -170,7 +181,8 @@ gst_fd_mem_share (GstMemory * gmem, gssize offset, gssize size)
  * Since: 1.2
  */
 GstMemory *
-__gst_fd_memory_new (GstAllocator * allocator, gint fd, gsize size)
+__gst_fd_memory_new (GstAllocator * allocator, gint fd, gsize size,
+    GstFdMemoryFlags flags)
 {
 #ifdef HAVE_MMAP
   GstFdMemory *mem;
@@ -178,6 +190,7 @@ __gst_fd_memory_new (GstAllocator * allocator, gint fd, gsize size)
   mem = g_slice_new0 (GstFdMemory);
   gst_memory_init (GST_MEMORY_CAST (mem), 0, allocator, NULL, size, 0, 0, size);
 
+  mem->flags = flags;
   mem->fd = fd;
   g_mutex_init (&mem->lock);
 
diff --git a/gst-libs/gst/allocators/gstfdmemory.h b/gst-libs/gst/allocators/gstfdmemory.h
index d85bc43718..9f28332937 100644
--- a/gst-libs/gst/allocators/gstfdmemory.h
+++ b/gst-libs/gst/allocators/gstfdmemory.h
@@ -25,8 +25,24 @@
 
 G_BEGIN_DECLS
 
+/**
+ * @GST_FD_MEMORY_FLAG_NONE: no flag
+ * @GST_FD_MEMORY_FLAG_KEEP_MAPPED: once the memory is mapped,
+ *        keep it mapped until the memory is destroyed.
+ * @GST_FD_MEMORY_FLAG_MAP_PRIVATE: do a private mapping instead of
+ *        the default shared mapping.
+ *
+ * Various flags to control the operation of the fd backed memory.
+ */
+typedef enum {
+  GST_FD_MEMORY_FLAG_NONE = 0,
+  GST_FD_MEMORY_FLAG_KEEP_MAPPED = (1 << 0),
+  GST_FD_MEMORY_FLAG_MAP_PRIVATE = (1 << 1),
+} GstFdMemoryFlags;
+
 /*
- * GstFdfMemory
+ * GstFdMemory
+ * @flags: #GstFdMemoryFlags
  * @fd: the file descriptor associated this memory
  * @data: mmapped address
  * @mmapping_flags: mmapping flags
@@ -37,6 +53,7 @@ typedef struct
 {
   GstMemory mem;
 
+  GstFdMemoryFlags flags;
   gint fd;
   gpointer data;
   gint mmapping_flags;
@@ -47,7 +64,8 @@ typedef struct
 void        __gst_fd_memory_class_init_allocator  (GstAllocatorClass * allocator);
 void        __gst_fd_memory_init_allocator        (GstAllocator * allocator, const gchar *type);
 
-GstMemory * __gst_fd_memory_new                   (GstAllocator * allocator, gint fd, gsize size);
+GstMemory * __gst_fd_memory_new                   (GstAllocator * allocator, gint fd, gsize size,
+                                                   GstFdMemoryFlags flags);
 
 
 G_END_DECLS