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![Hans Verkuil](/assets/img/avatar_default.png)
This reverts commit a242f42610
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That commit actually caused deadlocks, rather then fixing them.
If ext_lock is set to NULL (otherwise videobuf_queue_lock doesn't do
anything), then you get this deadlock:
The driver's mmap function calls videobuf_mmap_mapper which calls
videobuf_queue_lock on q. videobuf_mmap_mapper calls __videobuf_mmap_mapper,
__videobuf_mmap_mapper calls videobuf_vm_open and videobuf_vm_open
calls videobuf_queue_lock on q (introduced by above patch): deadlocked.
This affects drivers using dma-contig and dma-vmalloc. Only dma-sg is
not affected since it doesn't call videobuf_vm_open from __videobuf_mmap_mapper.
Most drivers these days have a non-NULL ext_lock. Those that still use
NULL there are all fairly obscure drivers, which is why this hasn't been
seen earlier.
Since everything worked perfectly fine for many years I prefer to just
revert this patch rather than trying to fix it. videobuf is quite fragile
and I rather not touch it too much. Work is (slowly) progressing to move
everything over to vb2 or at the very least use non-NULL ext_lock in
videobuf.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: <stable@vger.kernel.org> # for v3.11 and up
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Reported-by: Pete Eberlein <pete@sensoray.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
349 lines
8.3 KiB
C
349 lines
8.3 KiB
C
/*
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* helper functions for vmalloc video4linux capture buffers
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*
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* The functions expect the hardware being able to scatter gather
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* (i.e. the buffers are not linear in physical memory, but fragmented
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* into PAGE_SIZE chunks). They also assume the driver does not need
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* to touch the video data.
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*
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* (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/slab.h>
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#include <linux/interrupt.h>
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#include <linux/pci.h>
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#include <linux/vmalloc.h>
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#include <linux/pagemap.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include <media/videobuf-vmalloc.h>
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#define MAGIC_DMABUF 0x17760309
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#define MAGIC_VMAL_MEM 0x18221223
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#define MAGIC_CHECK(is, should) \
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if (unlikely((is) != (should))) { \
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printk(KERN_ERR "magic mismatch: %x (expected %x)\n", \
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is, should); \
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BUG(); \
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}
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static int debug;
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module_param(debug, int, 0644);
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MODULE_DESCRIPTION("helper module to manage video4linux vmalloc buffers");
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MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
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MODULE_LICENSE("GPL");
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#define dprintk(level, fmt, arg...) \
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if (debug >= level) \
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printk(KERN_DEBUG "vbuf-vmalloc: " fmt , ## arg)
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/***************************************************************************/
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static void videobuf_vm_open(struct vm_area_struct *vma)
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{
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struct videobuf_mapping *map = vma->vm_private_data;
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dprintk(2, "vm_open %p [count=%u,vma=%08lx-%08lx]\n", map,
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map->count, vma->vm_start, vma->vm_end);
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map->count++;
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}
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static void videobuf_vm_close(struct vm_area_struct *vma)
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{
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struct videobuf_mapping *map = vma->vm_private_data;
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struct videobuf_queue *q = map->q;
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int i;
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dprintk(2, "vm_close %p [count=%u,vma=%08lx-%08lx]\n", map,
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map->count, vma->vm_start, vma->vm_end);
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map->count--;
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if (0 == map->count) {
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struct videobuf_vmalloc_memory *mem;
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dprintk(1, "munmap %p q=%p\n", map, q);
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videobuf_queue_lock(q);
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/* We need first to cancel streams, before unmapping */
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if (q->streaming)
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videobuf_queue_cancel(q);
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for (i = 0; i < VIDEO_MAX_FRAME; i++) {
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if (NULL == q->bufs[i])
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continue;
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if (q->bufs[i]->map != map)
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continue;
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mem = q->bufs[i]->priv;
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if (mem) {
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/* This callback is called only if kernel has
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allocated memory and this memory is mmapped.
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In this case, memory should be freed,
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in order to do memory unmap.
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*/
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MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
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/* vfree is not atomic - can't be
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called with IRQ's disabled
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*/
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dprintk(1, "%s: buf[%d] freeing (%p)\n",
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__func__, i, mem->vaddr);
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vfree(mem->vaddr);
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mem->vaddr = NULL;
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}
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q->bufs[i]->map = NULL;
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q->bufs[i]->baddr = 0;
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}
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kfree(map);
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videobuf_queue_unlock(q);
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}
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return;
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}
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static const struct vm_operations_struct videobuf_vm_ops = {
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.open = videobuf_vm_open,
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.close = videobuf_vm_close,
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};
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/* ---------------------------------------------------------------------
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* vmalloc handlers for the generic methods
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*/
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/* Allocated area consists on 3 parts:
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struct video_buffer
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struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
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struct videobuf_dma_sg_memory
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*/
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static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
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{
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struct videobuf_vmalloc_memory *mem;
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struct videobuf_buffer *vb;
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vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
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if (!vb)
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return vb;
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mem = vb->priv = ((char *)vb) + size;
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mem->magic = MAGIC_VMAL_MEM;
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dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
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__func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
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mem, (long)sizeof(*mem));
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return vb;
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}
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static int __videobuf_iolock(struct videobuf_queue *q,
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struct videobuf_buffer *vb,
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struct v4l2_framebuffer *fbuf)
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{
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struct videobuf_vmalloc_memory *mem = vb->priv;
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int pages;
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BUG_ON(!mem);
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MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
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switch (vb->memory) {
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case V4L2_MEMORY_MMAP:
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dprintk(1, "%s memory method MMAP\n", __func__);
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/* All handling should be done by __videobuf_mmap_mapper() */
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if (!mem->vaddr) {
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printk(KERN_ERR "memory is not alloced/mmapped.\n");
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return -EINVAL;
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}
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break;
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case V4L2_MEMORY_USERPTR:
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pages = PAGE_ALIGN(vb->size);
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dprintk(1, "%s memory method USERPTR\n", __func__);
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if (vb->baddr) {
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printk(KERN_ERR "USERPTR is currently not supported\n");
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return -EINVAL;
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}
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/* The only USERPTR currently supported is the one needed for
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* read() method.
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*/
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mem->vaddr = vmalloc_user(pages);
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if (!mem->vaddr) {
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printk(KERN_ERR "vmalloc (%d pages) failed\n", pages);
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return -ENOMEM;
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}
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dprintk(1, "vmalloc is at addr %p (%d pages)\n",
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mem->vaddr, pages);
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#if 0
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int rc;
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/* Kernel userptr is used also by read() method. In this case,
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there's no need to remap, since data will be copied to user
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*/
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if (!vb->baddr)
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return 0;
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/* FIXME: to properly support USERPTR, remap should occur.
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The code below won't work, since mem->vma = NULL
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*/
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/* Try to remap memory */
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rc = remap_vmalloc_range(mem->vma, (void *)vb->baddr, 0);
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if (rc < 0) {
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printk(KERN_ERR "mmap: remap failed with error %d", rc);
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return -ENOMEM;
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}
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#endif
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break;
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case V4L2_MEMORY_OVERLAY:
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default:
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dprintk(1, "%s memory method OVERLAY/unknown\n", __func__);
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/* Currently, doesn't support V4L2_MEMORY_OVERLAY */
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printk(KERN_ERR "Memory method currently unsupported.\n");
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return -EINVAL;
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}
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return 0;
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}
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static int __videobuf_mmap_mapper(struct videobuf_queue *q,
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struct videobuf_buffer *buf,
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struct vm_area_struct *vma)
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{
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struct videobuf_vmalloc_memory *mem;
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struct videobuf_mapping *map;
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int retval, pages;
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dprintk(1, "%s\n", __func__);
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/* create mapping + update buffer list */
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map = kzalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
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if (NULL == map)
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return -ENOMEM;
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buf->map = map;
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map->q = q;
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buf->baddr = vma->vm_start;
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mem = buf->priv;
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BUG_ON(!mem);
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MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
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pages = PAGE_ALIGN(vma->vm_end - vma->vm_start);
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mem->vaddr = vmalloc_user(pages);
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if (!mem->vaddr) {
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printk(KERN_ERR "vmalloc (%d pages) failed\n", pages);
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goto error;
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}
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dprintk(1, "vmalloc is at addr %p (%d pages)\n", mem->vaddr, pages);
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/* Try to remap memory */
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retval = remap_vmalloc_range(vma, mem->vaddr, 0);
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if (retval < 0) {
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printk(KERN_ERR "mmap: remap failed with error %d. ", retval);
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vfree(mem->vaddr);
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goto error;
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}
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vma->vm_ops = &videobuf_vm_ops;
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vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
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vma->vm_private_data = map;
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dprintk(1, "mmap %p: q=%p %08lx-%08lx (%lx) pgoff %08lx buf %d\n",
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map, q, vma->vm_start, vma->vm_end,
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(long int)buf->bsize,
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vma->vm_pgoff, buf->i);
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videobuf_vm_open(vma);
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return 0;
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error:
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mem = NULL;
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kfree(map);
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return -ENOMEM;
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}
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static struct videobuf_qtype_ops qops = {
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.magic = MAGIC_QTYPE_OPS,
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.alloc_vb = __videobuf_alloc_vb,
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.iolock = __videobuf_iolock,
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.mmap_mapper = __videobuf_mmap_mapper,
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.vaddr = videobuf_to_vmalloc,
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};
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void videobuf_queue_vmalloc_init(struct videobuf_queue *q,
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const struct videobuf_queue_ops *ops,
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struct device *dev,
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spinlock_t *irqlock,
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enum v4l2_buf_type type,
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enum v4l2_field field,
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unsigned int msize,
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void *priv,
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struct mutex *ext_lock)
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{
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videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
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priv, &qops, ext_lock);
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}
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EXPORT_SYMBOL_GPL(videobuf_queue_vmalloc_init);
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void *videobuf_to_vmalloc(struct videobuf_buffer *buf)
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{
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struct videobuf_vmalloc_memory *mem = buf->priv;
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BUG_ON(!mem);
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MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
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return mem->vaddr;
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}
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EXPORT_SYMBOL_GPL(videobuf_to_vmalloc);
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void videobuf_vmalloc_free(struct videobuf_buffer *buf)
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{
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struct videobuf_vmalloc_memory *mem = buf->priv;
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/* mmapped memory can't be freed here, otherwise mmapped region
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would be released, while still needed. In this case, the memory
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release should happen inside videobuf_vm_close().
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So, it should free memory only if the memory were allocated for
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read() operation.
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*/
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if ((buf->memory != V4L2_MEMORY_USERPTR) || buf->baddr)
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return;
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if (!mem)
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return;
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MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
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vfree(mem->vaddr);
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mem->vaddr = NULL;
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return;
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}
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EXPORT_SYMBOL_GPL(videobuf_vmalloc_free);
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