gstreamer/gst-libs/gst/allocators/gstdmabuf.c
Michael Olbrich 3c66c2a43d dmabuf: fix mmap counting
A successful gst_dmabuf_mem_map must always increment the mmap count.
Otherwise the first gst_dmabuf_mem_unmap will unmap the memory and all
other user will access unmapped memory.

https://bugzilla.gnome.org/show_bug.cgi?id=706680
2013-08-26 09:29:32 +02:00

351 lines
8.3 KiB
C

/* GStreamer dmabuf allocator
* Copyright (C) 2013 Linaro SA
* Author: Benjamin Gaignard <benjamin.gaignard@linaro.org> for Linaro.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for mordetails.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "gstdmabuf.h"
/**
* SECTION:gstdmabuf
* @short_description: Memory wrapper for Linux dmabuf memory
* @see_also: #GstMemory
*
* Since: 1.2
*/
#ifdef HAVE_MMAP
#include <sys/mman.h>
#include <unistd.h>
/*
* GstDmaBufMemory
* @fd: the file descriptor associated this memory
* @data: mmapped address
* @mmapping_flags: mmapping flags
* @mmap_count: mmapping counter
* @lock: a mutex to make mmapping thread safe
*/
typedef struct
{
GstMemory mem;
gint fd;
gpointer data;
gint mmapping_flags;
gint mmap_count;
gsize mmap_size;
GMutex lock;
} GstDmaBufMemory;
GST_DEBUG_CATEGORY_STATIC (dmabuf_debug);
#define GST_CAT_DEFAULT dmabuf_debug
static void
gst_dmabuf_allocator_free (GstAllocator * allocator, GstMemory * gmem)
{
GstDmaBufMemory *mem = (GstDmaBufMemory *) gmem;
if (mem->data) {
g_warning (G_STRLOC ":%s: Freeing memory %p still mapped", G_STRFUNC, mem);
munmap ((void *) mem->data, mem->mmap_size);
}
close (mem->fd);
g_mutex_clear (&mem->lock);
g_slice_free (GstDmaBufMemory, mem);
GST_DEBUG ("%p: freed", mem);
}
static gpointer
gst_dmabuf_mem_map (GstMemory * gmem, gsize maxsize, GstMapFlags flags)
{
GstDmaBufMemory *mem = (GstDmaBufMemory *) gmem;
gint prot;
gpointer ret = NULL;
g_mutex_lock (&mem->lock);
prot = flags & GST_MAP_READ ? PROT_READ : 0;
prot |= flags & GST_MAP_WRITE ? PROT_WRITE : 0;
/* do not mmap twice the buffer */
if (mem->data) {
/* only return address if mapping flags are a subset
* of the previous flags */
if ((mem->mmapping_flags & prot) && (mem->mmap_size >= maxsize)) {
ret = mem->data;
mem->mmap_count++;
}
goto out;
}
if (mem->fd != -1) {
mem->data = mmap (0, maxsize, prot, MAP_SHARED, mem->fd, 0);
if (mem->data == MAP_FAILED) {
mem->data = NULL;
GST_ERROR ("%p: fd %d: mmap failed: %s", mem, mem->fd,
g_strerror (errno));
goto out;
}
}
GST_DEBUG ("%p: fd %d: mapped %p", mem, mem->fd, mem->data);
if (mem->data) {
mem->mmapping_flags = prot;
mem->mmap_size = maxsize;
mem->mmap_count++;
ret = mem->data;
}
out:
g_mutex_unlock (&mem->lock);
return ret;
}
static void
gst_dmabuf_mem_unmap (GstMemory * gmem)
{
GstDmaBufMemory *mem = (GstDmaBufMemory *) gmem;
g_mutex_lock (&mem->lock);
if (mem->data && !(--mem->mmap_count)) {
munmap ((void *) mem->data, mem->mmap_size);
mem->data = NULL;
mem->mmap_size = 0;
mem->mmapping_flags = 0;
GST_DEBUG ("%p: fd %d unmapped", mem, mem->fd);
}
g_mutex_unlock (&mem->lock);
}
static GstMemory *
gst_dmabuf_mem_share (GstMemory * gmem, gssize offset, gssize size)
{
GstDmaBufMemory *mem = (GstDmaBufMemory *) gmem;
GstDmaBufMemory *sub;
GstMemory *parent;
GST_DEBUG ("%p: share %" G_GSSIZE_FORMAT " %" G_GSIZE_FORMAT, mem, offset,
size);
/* find the real parent */
if ((parent = mem->mem.parent) == NULL)
parent = (GstMemory *) mem;
if (size == -1)
size = gmem->maxsize - offset;
sub = g_slice_new0 (GstDmaBufMemory);
/* the shared memory is always readonly */
gst_memory_init (GST_MEMORY_CAST (sub), GST_MINI_OBJECT_FLAGS (parent) |
GST_MINI_OBJECT_FLAG_LOCK_READONLY, mem->mem.allocator, parent,
mem->mem.maxsize, mem->mem.align, mem->mem.offset + offset, size);
sub->fd = dup (mem->fd);
g_mutex_init (&sub->lock);
return GST_MEMORY_CAST (sub);
}
typedef struct
{
GstAllocator parent;
} GstDmaBufAllocator;
typedef struct
{
GstAllocatorClass parent_class;
} GstDmaBufAllocatorClass;
GType dmabuf_mem_allocator_get_type (void);
G_DEFINE_TYPE (GstDmaBufAllocator, dmabuf_mem_allocator, GST_TYPE_ALLOCATOR);
#define GST_TYPE_DMABUF_ALLOCATOR (dmabuf_mem_allocator_get_type())
#define GST_IS_DMABUF_ALLOCATOR(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_DMABUF_ALLOCATOR))
static void
dmabuf_mem_allocator_class_init (GstDmaBufAllocatorClass * klass)
{
GstAllocatorClass *allocator_class;
allocator_class = (GstAllocatorClass *) klass;
allocator_class->alloc = NULL;
allocator_class->free = gst_dmabuf_allocator_free;
}
static void
dmabuf_mem_allocator_init (GstDmaBufAllocator * allocator)
{
GstAllocator *alloc = GST_ALLOCATOR_CAST (allocator);
alloc->mem_type = GST_ALLOCATOR_DMABUF;
alloc->mem_map = gst_dmabuf_mem_map;
alloc->mem_unmap = gst_dmabuf_mem_unmap;
alloc->mem_share = gst_dmabuf_mem_share;
/* Use the default, fallback copy function */
GST_OBJECT_FLAG_SET (allocator, GST_ALLOCATOR_FLAG_CUSTOM_ALLOC);
}
static void
gst_dmabuf_mem_init (void)
{
GstAllocator *allocator =
g_object_new (dmabuf_mem_allocator_get_type (), NULL);
gst_allocator_register (GST_ALLOCATOR_DMABUF, allocator);
GST_DEBUG_CATEGORY_INIT (dmabuf_debug, "dmabuf", 0, "dmabuf memory");
}
/**
* gst_dmabuf_allocator_obtain:
*
* Return a dmabuf allocator.
*
* Returns: (transfer full): a dmabuf allocator, or NULL if the allocator
* isn't available. Use gst_object_unref() to release the allocator after
* usage
*
* Since: 1.2
*/
GstAllocator *
gst_dmabuf_allocator_obtain (void)
{
static GOnce dmabuf_allocator_once = G_ONCE_INIT;
GstAllocator *allocator;
g_once (&dmabuf_allocator_once, (GThreadFunc) gst_dmabuf_mem_init, NULL);
allocator = gst_allocator_find (GST_ALLOCATOR_DMABUF);
if (!allocator)
GST_WARNING ("No allocator named %s found", GST_ALLOCATOR_DMABUF);
return allocator;
}
/**
* gst_dmabuf_allocator_alloc:
* @allocator: (allow-none): allocator to be used for this memory
* @fd: dmabuf file descriptor
* @size: memory size
*
* Return a %GstMemory that wraps a dmabuf file descriptor.
*
* Returns: (transfer full): a GstMemory based on @allocator.
* When the buffer will be released dmabuf allocator will close the @fd.
* The memory is only mmapped on gst_buffer_mmap() request.
*
* Since: 1.2
*/
GstMemory *
gst_dmabuf_allocator_alloc (GstAllocator * allocator, gint fd, gsize size)
{
GstDmaBufMemory *mem;
if (!allocator) {
allocator = gst_dmabuf_allocator_obtain ();
}
if (!GST_IS_DMABUF_ALLOCATOR (allocator)) {
GST_WARNING ("it isn't the correct allocator for dmabuf");
return NULL;
}
GST_DEBUG ("alloc from allocator %p", allocator);
mem = g_slice_new0 (GstDmaBufMemory);
gst_memory_init (GST_MEMORY_CAST (mem), 0, allocator, NULL, size, 0, 0, size);
mem->fd = fd;
g_mutex_init (&mem->lock);
GST_DEBUG ("%p: fd: %d size %" G_GSIZE_FORMAT, mem, mem->fd,
mem->mem.maxsize);
return (GstMemory *) mem;
}
/**
* gst_dmabuf_memory_get_fd:
* @mem: the memory to get the file descriptor
*
* Return the file descriptor associated with @mem.
*
* Returns: the file descriptor associated with the memory, or -1
*
* Since: 1.2
*/
gint
gst_dmabuf_memory_get_fd (GstMemory * mem)
{
GstDmaBufMemory *dbmem = (GstDmaBufMemory *) mem;
g_return_val_if_fail (gst_is_dmabuf_memory (mem), -1);
return dbmem->fd;
}
/**
* gst_is_dmabuf_memory:
* @mem: the memory to be check
*
* Check if @mem is dmabuf memory.
*
* Returns: %TRUE if @mem is dmabuf memory, otherwise %FALSE
*
* Since: 1.2
*/
gboolean
gst_is_dmabuf_memory (GstMemory * mem)
{
return gst_memory_is_type (mem, GST_ALLOCATOR_DMABUF);
}
#else /* !HAVE_MMAP */
GstAllocator *
gst_dmabuf_allocator_obtain (void)
{
return NULL;
}
GstMemory *
gst_dmabuf_allocator_alloc (GstAllocator * allocator, gint fd, gsize size)
{
return NULL;
}
gint
gst_dmabuf_memory_get_fd (GstMemory * mem)
{
return -1;
}
gboolean
gst_is_dmabuf_memory (GstMemory * mem)
{
return FALSE;
}
#endif /* HAVE_MMAP */