Re: [PATCH 1/2] uio: introduce UIO_MEM_DMA_COHERENT type
From: Thomas Weißschuh <hidden>
Date: 2024-03-12 08:40:25
Also in:
linux-scsi, lkml
Hi, On Wed, Jan 31, 2024 at 11:17:31AM -0800, Chris Leech wrote:
quoted hunk ↗ jump to hunk
Add a UIO memtype specifically for sharing dma_alloc_coherent memory with userspace, backed by dma_mmap_coherent. This is mainly for the bnx2/bnx2x/bnx2i "cnic" interface, although there are a few other uio drivers which map dma_alloc_coherent memory and could be converted to use dma_mmap_coherent as well. Signed-off-by: Nilesh Javali <njavali@marvell.com> Signed-off-by: Chris Leech <cleech@redhat.com> --- drivers/uio/uio.c | 40 ++++++++++++++++++++++++++++++++++++++ include/linux/uio_driver.h | 3 +++ 2 files changed, 43 insertions(+)diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index 2d572f6c8ec83..dde3f49855233 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c@@ -24,6 +24,7 @@
[..]
+static int uio_mmap_dma_coherent(struct vm_area_struct *vma)
+{
+ struct uio_device *idev = vma->vm_private_data;
+ struct uio_mem *mem;
+ void *addr;
+ int ret = 0;
+ int mi;
+
+ mi = uio_find_mem_index(vma);
+ if (mi < 0)
+ return -EINVAL;
+
+ mem = idev->info->mem + mi;
+
+ if (mem->dma_addr & ~PAGE_MASK)
+ return -ENODEV;
+ if (vma->vm_end - vma->vm_start > mem->size)
+ return -EINVAL;
+
+ /*
+ * UIO uses offset to index into the maps for a device.
+ * We need to clear vm_pgoff for dma_mmap_coherent.
+ */
+ vma->vm_pgoff = 0;
+
+ addr = (void *)mem->addr;
This cast introduces a build error when building with
sizeof(void *) != sizeof(phys_addr_t).
For example on i386 with PHYS_ADDR_T_64BIT.
(Enabled through allmodconfig)
drivers/uio/uio.c: In function 'uio_mmap_dma_coherent':
drivers/uio/uio.c:795:16: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
795 | addr = (void *)mem->addr;
| ^
drivers/uio/uio_pruss.c: In function 'pruss_probe':
drivers/uio/uio_pruss.c:194:34: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
194 | p->mem[2].addr = (phys_addr_t) gdev->ddr_vaddr;
| ^
drivers/uio/uio_dmem_genirq.c: In function 'uio_dmem_genirq_open':
drivers/uio/uio_dmem_genirq.c:63:39: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
63 | uiomem->addr = addr ? (phys_addr_t) addr : DMEM_MAP_ERROR;
| ^
drivers/uio/uio_dmem_genirq.c: In function 'uio_dmem_genirq_release':
drivers/uio/uio_dmem_genirq.c:92:43: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
92 | (void *) uiomem->addr,
As you can see some other files are also affected, which seem to be
triggered by other but related patches.
This is on next-20240312.
+ ret = dma_mmap_coherent(mem->dma_device, + vma, + addr, + mem->dma_addr, + vma->vm_end - vma->vm_start); + vma->vm_pgoff = mi; + + return ret; +} +
[..] Thomas