On 11/13/22 18:05, Lukasz Wiecaszek wrote: > The reason behind that patch is associated with videobuf2 subsystem > (or more genrally with v4l2 framework) and user created > dma buffers (udmabuf). In some circumstances > when dealing with V4L2_MEMORY_DMABUF buffers videobuf2 subsystem > wants to use dma_buf_vmap() method on the attached dma buffer. > As udmabuf does not have .vmap operation implemented, > such dma_buf_vmap() natually fails. > > videobuf2_common: [cap-000000003473b2f1] __vb2_queue_alloc: allocated 3 buffers, 1 plane(s) each > videobuf2_common: [cap-000000003473b2f1] __prepare_dmabuf: buffer for plane 0 changed > videobuf2_common: [cap-000000003473b2f1] __prepare_dmabuf: failed to map dmabuf for plane 0 > videobuf2_common: [cap-000000003473b2f1] __buf_prepare: buffer preparation failed: -14 > > The patch itself seems to be strighforward. > It adds implementation of .vmap method to 'struct dma_buf_ops udmabuf_ops'. > .vmap method itself uses vm_map_ram() to map pages linearly > into the kernel virtual address space (only if such mapping > hasn't been created yet). > > Signed-off-by: Lukasz Wiecaszek <lukasz.wiecaszek@xxxxxxxxx> > Reported-by: kernel test robot <lkp@xxxxxxxxx> > --- > v1: https://lore.kernel.org/linux-media/202211120352.G7WPASoP-lkp@xxxxxxxxx/T/#t > > v1 -> v2: Patch prepared and tested against 6.1.0-rc2+ > > drivers/dma-buf/udmabuf.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c > index 2bcdb935a3ac..2ca0e3639360 100644 > --- a/drivers/dma-buf/udmabuf.c > +++ b/drivers/dma-buf/udmabuf.c > @@ -12,6 +12,8 @@ > #include <linux/slab.h> > #include <linux/udmabuf.h> > #include <linux/hugetlb.h> > +#include <linux/vmalloc.h> > +#include <linux/iosys-map.h> > > static int list_limit = 1024; > module_param(list_limit, int, 0644); > @@ -26,6 +28,7 @@ struct udmabuf { > struct page **pages; > struct sg_table *sg; > struct miscdevice *device; > + void *vaddr; > }; > > static vm_fault_t udmabuf_vm_fault(struct vm_fault *vmf) > @@ -57,6 +60,21 @@ static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma) > return 0; > } > > +static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map) > +{ > + struct udmabuf *ubuf = buf->priv; > + > + if (!ubuf->vaddr) { > + ubuf->vaddr = vm_map_ram(ubuf->pages, ubuf->pagecount, -1); > + if (!ubuf->vaddr) > + return -EINVAL; > + } > + > + iosys_map_set_vaddr(map, ubuf->vaddr); > + > + return 0; > +} > + > static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf, > enum dma_data_direction direction) > { > @@ -159,6 +177,7 @@ static const struct dma_buf_ops udmabuf_ops = { > .unmap_dma_buf = unmap_udmabuf, > .release = release_udmabuf, > .mmap = mmap_udmabuf, > + .vmap = vmap_udmabuf, > .begin_cpu_access = begin_cpu_udmabuf, > .end_cpu_access = end_cpu_udmabuf, > }; Where is vunmap? -- Best regards, Dmitry
