[PATCH] media: vb2: vmalloc-based allocator user pointer handling

[Andrzej Pietrasiewicz]

vmalloc-based allocator user pointer handling

Signed-off-by: Andrzej Pietrasiewicz <andrze...@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.p...@samsung.com>
---
 drivers/media/video/videobuf2-vmalloc.c |   86 ++++++++++++++++++++++++++++++-
 1 files changed, 85 insertions(+), 1 deletions(-)

diff --git a/drivers/media/video/videobuf2-vmalloc.c 
b/drivers/media/video/videobuf2-vmalloc.c
index a3a8842..ee0ee37 100644
--- a/drivers/media/video/videobuf2-vmalloc.c
+++ b/drivers/media/video/videobuf2-vmalloc.c
@@ -12,6 +12,7 @@
 
 #include <linux/module.h>
 #include <linux/mm.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 
@@ -20,7 +21,10 @@
 
 struct vb2_vmalloc_buf {
        void                            *vaddr;
+       struct page                     **pages;
+       int                             write;
        unsigned long                   size;
+       unsigned int                    n_pages;
        atomic_t                        refcount;
        struct vb2_vmarea_handler       handler;
 };
@@ -66,6 +70,83 @@ static void vb2_vmalloc_put(void *buf_priv)
        }
 }
 
+static void *vb2_vmalloc_get_userptr(void *alloc_ctx, unsigned long vaddr,
+                                    unsigned long size, int write)
+{
+       struct vb2_vmalloc_buf *buf;
+
+       unsigned long first, last;
+       int n_pages_from_user, offset;
+
+       buf = kzalloc(sizeof *buf, GFP_KERNEL);
+       if (!buf)
+               return NULL;
+
+       buf->vaddr = NULL;
+       buf->write = write;
+       offset = vaddr & ~PAGE_MASK;
+       buf->size = size;
+
+       first = (vaddr & PAGE_MASK) >> PAGE_SHIFT;
+       last  = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
+       buf->n_pages = last - first + 1;
+       buf->pages = kzalloc(buf->n_pages * sizeof(struct page *), GFP_KERNEL);
+       if (!buf->pages)
+               goto userptr_fail_pages_array_alloc;
+
+       down_read(&current->mm->mmap_sem);
+       n_pages_from_user = get_user_pages(current, current->mm,
+                                            vaddr & PAGE_MASK,
+                                            buf->n_pages,
+                                            write,
+                                            1, /* force */
+                                            buf->pages,
+                                            NULL);
+       up_read(&current->mm->mmap_sem);
+       if (n_pages_from_user != buf->n_pages)
+               goto userptr_fail_get_user_pages;
+
+       buf->vaddr = vm_map_ram(buf->pages, buf->n_pages, -1, PAGE_KERNEL);
+
+       if (buf->vaddr) {
+               buf->vaddr += offset;
+               return buf;
+       }
+
+userptr_fail_get_user_pages:
+       printk(KERN_DEBUG "get_user_pages requested/got: %d/%d]\n",
+              n_pages_from_user, buf->n_pages);
+       while (--n_pages_from_user >= 0)
+               put_page(buf->pages[n_pages_from_user]);
+       kfree(buf->pages);
+
+userptr_fail_pages_array_alloc:
+       kfree(buf);
+
+       return NULL;
+}
+
+static void vb2_vmalloc_put_userptr(void *buf_priv)
+{
+       struct vb2_vmalloc_buf *buf = buf_priv;
+
+       int i = buf->n_pages;
+       int offset = (unsigned long)buf->vaddr & ~PAGE_MASK;
+
+       printk(KERN_DEBUG "%s: Releasing userspace buffer of %d pages\n",
+              __func__, buf->n_pages);
+       if (buf->vaddr)
+               vm_unmap_ram((const void *)((unsigned long)buf->vaddr - offset),
+                            buf->n_pages);
+       while (--i >= 0) {
+               if (buf->write)
+                       set_page_dirty_lock(buf->pages[i]);
+               put_page(buf->pages[i]);
+       }
+       kfree(buf->pages);
+       kfree(buf);
+}
+
 static void *vb2_vmalloc_vaddr(void *buf_priv)
 {
        struct vb2_vmalloc_buf *buf = buf_priv;
@@ -73,7 +154,8 @@ static void *vb2_vmalloc_vaddr(void *buf_priv)
        BUG_ON(!buf);
 
        if (!buf->vaddr) {
-               printk(KERN_ERR "Address of an unallocated plane requested\n");
+               printk(KERN_ERR "Address of an unallocated plane requested "
+                      "or cannot map user pointer\n");
                return NULL;
        }
 
@@ -121,6 +203,8 @@ static int vb2_vmalloc_mmap(void *buf_priv, struct 
vm_area_struct *vma)
 const struct vb2_mem_ops vb2_vmalloc_memops = {
        .alloc          = vb2_vmalloc_alloc,
        .put            = vb2_vmalloc_put,
+       .get_userptr    = vb2_vmalloc_get_userptr,
+       .put_userptr    = vb2_vmalloc_put_userptr,
        .vaddr          = vb2_vmalloc_vaddr,
        .mmap           = vb2_vmalloc_mmap,
        .num_users      = vb2_vmalloc_num_users,
-- 
1.7.0.4

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