From 7fd4b41f053681cccf188cc1731ae43fe38fa969 Mon Sep 17 00:00:00 2001 From: Paul Cassella Date: Sat, 12 Feb 2011 10:39:51 -0300 Subject: [PATCH] [media] ivtv: yuv: handle get_user_pages() -errno returns get_user_pages() may return -errno, such as -EFAULT. So don't blindly use its return value as an offset into dma->map[] for the next get_user_pages() call. Since we'll give up and return an error if either fails, don't even make the second call if the first failed to give us exactly what we were looking for. The old code would also call put_page() on as many elements of dma->map[] as we'd asked for, regardless of how many were valid. [Andy Walls modified this patch to return -EFAULT instead of -EINVAL as Paul's observation "I'm not sure -EINVAL is the best return code vs -EFAULT or -ENOMEM, [...]" was correct. The return value bubbles up as a return code for write(), for which the V4L2 API spec indicates EINVAL is incorrect and EFAULT is correct.] Signed-off-by: Paul Cassella Signed-off-by: Andy Walls Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/ivtv/ivtv-yuv.c | 52 ++++++++++++++++++++++------- 1 file changed, 40 insertions(+), 12 deletions(-) diff --git a/drivers/media/video/ivtv/ivtv-yuv.c b/drivers/media/video/ivtv/ivtv-yuv.c index c0875378acc2..dcbab6ad4c26 100644 --- a/drivers/media/video/ivtv/ivtv-yuv.c +++ b/drivers/media/video/ivtv/ivtv-yuv.c @@ -77,23 +77,51 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma, /* Get user pages for DMA Xfer */ down_read(¤t->mm->mmap_sem); y_pages = get_user_pages(current, current->mm, y_dma.uaddr, y_dma.page_count, 0, 1, &dma->map[0], NULL); - uv_pages = get_user_pages(current, current->mm, uv_dma.uaddr, uv_dma.page_count, 0, 1, &dma->map[y_pages], NULL); + uv_pages = 0; /* silence gcc. value is set and consumed only if: */ + if (y_pages == y_dma.page_count) { + uv_pages = get_user_pages(current, current->mm, + uv_dma.uaddr, uv_dma.page_count, 0, 1, + &dma->map[y_pages], NULL); + } up_read(¤t->mm->mmap_sem); - dma->page_count = y_dma.page_count + uv_dma.page_count; - - if (y_pages + uv_pages != dma->page_count) { - IVTV_DEBUG_WARN - ("failed to map user pages, returned %d instead of %d\n", - y_pages + uv_pages, dma->page_count); - - for (i = 0; i < dma->page_count; i++) { - put_page(dma->map[i]); + if (y_pages != y_dma.page_count || uv_pages != uv_dma.page_count) { + int rc = -EFAULT; + + if (y_pages == y_dma.page_count) { + IVTV_DEBUG_WARN + ("failed to map uv user pages, returned %d " + "expecting %d\n", uv_pages, uv_dma.page_count); + + if (uv_pages >= 0) { + for (i = 0; i < uv_pages; i++) + put_page(dma->map[y_pages + i]); + rc = -EFAULT; + } else { + rc = uv_pages; + } + } else { + IVTV_DEBUG_WARN + ("failed to map y user pages, returned %d " + "expecting %d\n", y_pages, y_dma.page_count); } - dma->page_count = 0; - return -EINVAL; + if (y_pages >= 0) { + for (i = 0; i < y_pages; i++) + put_page(dma->map[i]); + /* + * Inherit the -EFAULT from rc's + * initialization, but allow it to be + * overriden by uv_pages above if it was an + * actual errno. + */ + } else { + rc = y_pages; + } + return rc; } + dma->page_count = y_pages + uv_pages; + /* Fill & map SG List */ if (ivtv_udma_fill_sg_list (dma, &uv_dma, ivtv_udma_fill_sg_list (dma, &y_dma, 0)) < 0) { IVTV_DEBUG_WARN("could not allocate bounce buffers for highmem userspace buffers\n"); -- 2.20.1