linux-kernel - [PATCH RESEND] drm/via: use get_user_pages

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Date:   Mon, 27 Feb 2017 21:50:08 +0000
From:   Lorenzo Stoakes <lstoakes@...il.com>
To:     Daniel Vetter <daniel@...ll.ch>
Cc:     linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-mm@...ck.org, Lorenzo Stoakes <lstoakes@...il.com>
Subject: [PATCH RESEND] drm/via: use get_user_pages_unlocked()

Moving from get_user_pages() to get_user_pages_unlocked() simplifies the code
and takes advantage of VM_FAULT_RETRY functionality when faulting in pages.

Signed-off-by: Lorenzo Stoakes <lstoakes@...il.com>
---
 drivers/gpu/drm/via/via_dmablit.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/via/via_dmablit.c b/drivers/gpu/drm/via/via_dmablit.c
index 1a3ad769f8c8..98aae9809249 100644
--- a/drivers/gpu/drm/via/via_dmablit.c
+++ b/drivers/gpu/drm/via/via_dmablit.c
@@ -238,13 +238,9 @@ via_lock_all_dma_pages(drm_via_sg_info_t *vsg,  drm_via_dmablit_t *xfer)
 	vsg->pages = vzalloc(sizeof(struct page *) * vsg->num_pages);
 	if (NULL == vsg->pages)
 		return -ENOMEM;
-	down_read(&current->mm->mmap_sem);
-	ret = get_user_pages((unsigned long)xfer->mem_addr,
-			     vsg->num_pages,
-			     (vsg->direction == DMA_FROM_DEVICE) ? FOLL_WRITE : 0,
-			     vsg->pages, NULL);
-
-	up_read(&current->mm->mmap_sem);
+	ret = get_user_pages_unlocked((unsigned long)xfer->mem_addr,
+			vsg->num_pages, vsg->pages,
+			(vsg->direction == DMA_FROM_DEVICE) ? FOLL_WRITE : 0);
 	if (ret != vsg->num_pages) {
 		if (ret < 0)
 			return ret;
-- 
2.11.1