linux-kernel - [PATCH] drivers/virt: use get_user_pages

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Message-Id: <20161101194332.23961-1-lstoakes@gmail.com>
Date:   Tue,  1 Nov 2016 19:43:32 +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>,
        Timur Tabi <timur@...escale.com>,
        Kumar Gala <galak@...nel.crashing.org>,
        Lorenzo Stoakes <lstoakes@...il.com>
Subject: [PATCH] drivers/virt: 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/virt/fsl_hypervisor.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/virt/fsl_hypervisor.c b/drivers/virt/fsl_hypervisor.c
index 150ce2a..d3eca87 100644
--- a/drivers/virt/fsl_hypervisor.c
+++ b/drivers/virt/fsl_hypervisor.c
@@ -243,11 +243,8 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
 	sg_list = PTR_ALIGN(sg_list_unaligned, sizeof(struct fh_sg_list));
 
 	/* Get the physical addresses of the source buffer */
-	down_read(&current->mm->mmap_sem);
-	num_pinned = get_user_pages(param.local_vaddr - lb_offset,
-		num_pages, (param.source == -1) ? 0 : FOLL_WRITE,
-		pages, NULL);
-	up_read(&current->mm->mmap_sem);
+	num_pinned = get_user_pages_unlocked(param.local_vaddr - lb_offset,
+		num_pages, pages, (param.source == -1) ? 0 : FOLL_WRITE);
 
 	if (num_pinned != num_pages) {
 		/* get_user_pages() failed */
-- 
2.10.2