1 files 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(&current->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(&current->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");