linux-kernel - [PATCH RESEND] rapidio: use get_user_pages

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Message-Id: <20170103205024.6704-1-lstoakes@gmail.com>
Date:   Tue,  3 Jan 2017 20:50:24 +0000
From:   Lorenzo Stoakes <lstoakes@...il.com>
To:     Matt Porter <mporter@...nel.crashing.org>,
        Alexandre Bounine <alexandre.bounine@....com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Lorenzo Stoakes <lstoakes@...il.com>
Subject: [PATCH RESEND] rapidio: 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/rapidio/devices/rio_mport_cdev.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c
index 9013a585507e..50b617af81bd 100644
--- a/drivers/rapidio/devices/rio_mport_cdev.c
+++ b/drivers/rapidio/devices/rio_mport_cdev.c
@@ -889,17 +889,16 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode,
 			goto err_req;
 		}

-		down_read(&current->mm->mmap_sem);
-		pinned = get_user_pages(
+		pinned = get_user_pages_unlocked(
 				(unsigned long)xfer->loc_addr & PAGE_MASK,
 				nr_pages,
-				dir == DMA_FROM_DEVICE ? FOLL_WRITE : 0,
-				page_list, NULL);
-		up_read(&current->mm->mmap_sem);
+				page_list,
+				dir == DMA_FROM_DEVICE ? FOLL_WRITE : 0);

 		if (pinned != nr_pages) {
 			if (pinned < 0) {
-				rmcd_error("get_user_pages err=%ld", pinned);
+				rmcd_error("get_user_pages_unlocked err=%ld",
+					   pinned);
 				nr_pages = 0;
 			} else
 				rmcd_error("pinned %ld out of %ld pages",
--
2.11.0