On Fri, Sep 30, 2016 at 02:59:59PM +0100, Chris Wilson wrote:
In order to keep the dmabuf alive whilst the mmap is, we need to hold a reference to the dmabuf and not the backing object. This is important as the dmabuf not only keeps the object alive, but also the device so that
dmabuf = vgem_create_dmabuf(); ptr = mmap(... dmabuf ...); close(dmabuf);
persists across module-unload as well as device closure.
I don't see where we grab the ref to the dma-buf here instead of the backing storage. And doesn't the exact same issue happen when you use dumb mmap? Or maybe I'm just a bit confused about what's going on here ... -Daniel
Testcase: igt/vgem_basic/unload Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Petri Latvala petri.latvala@intel.com
drivers/gpu/drm/vgem/vgem_drv.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c index f36c14729b55..74a83e41efa9 100644 --- a/drivers/gpu/drm/vgem/vgem_drv.c +++ b/drivers/gpu/drm/vgem/vgem_drv.c @@ -198,7 +198,6 @@ static struct drm_ioctl_desc vgem_ioctls[] = {
static int vgem_mmap(struct file *filp, struct vm_area_struct *vma) {
unsigned long flags = vma->vm_flags; int ret;
ret = drm_gem_mmap(filp, vma);
@@ -208,7 +207,7 @@ static int vgem_mmap(struct file *filp, struct vm_area_struct *vma) /* Keep the WC mmaping set by drm_gem_mmap() but our pages * are ordinary and not special. */
- vma->vm_flags = flags | VM_DONTEXPAND | VM_DONTDUMP;
- vma->vm_flags &= ~(VM_IO | VM_PFNMAP); return 0;
}
@@ -281,21 +280,11 @@ static int vgem_prime_mmap(struct drm_gem_object *obj, { int ret;
- if (obj->size < vma->vm_end - vma->vm_start)
return -EINVAL;- if (!obj->filp)
return -ENODEV;- ret = obj->filp->f_op->mmap(obj->filp, vma);
- ret = drm_gem_mmap_obj(obj, obj->size, vma); if (ret) return ret;
- fput(vma->vm_file);
- vma->vm_file = get_file(obj->filp);
- vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
- vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
- vma->vm_flags &= ~(VM_IO | VM_PFNMAP); return 0;
}
-- 2.9.3
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