linux-kernel - [PATCH] rapidio: use get_user_pages

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Date:   Tue,  1 Nov 2016 19:43:47 +0000
From:   Lorenzo Stoakes <lstoakes@...il.com>
To:     linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Michal Hocko <mhocko@...nel.org>,
        Matt Porter <mporter@...nel.crashing.org>,
        Alexandre Bounine <alexandre.bounine@....com>,
        Lorenzo Stoakes <lstoakes@...il.com>
Subject: [PATCH] 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 | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c
index 9013a58..5fdd081 100644
--- a/drivers/rapidio/devices/rio_mport_cdev.c
+++ b/drivers/rapidio/devices/rio_mport_cdev.c
@@ -889,13 +889,11 @@ 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) {
-- 
2.10.2