netdev - [PATCH v3 21/41] fsl_hypervisor: convert put_page() to put_user

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Date:   Tue,  6 Aug 2019 18:33:20 -0700
From:   john.hubbard@...il.com
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Chinner <david@...morbit.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ira Weiny <ira.weiny@...el.com>, Jan Kara <jack@...e.cz>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Jérôme Glisse <jglisse@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        amd-gfx@...ts.freedesktop.org, ceph-devel@...r.kernel.org,
        devel@...verdev.osuosl.org, devel@...ts.orangefs.org,
        dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
        kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-block@...r.kernel.org, linux-crypto@...r.kernel.org,
        linux-fbdev@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-media@...r.kernel.org, linux-mm@...ck.org,
        linux-nfs@...r.kernel.org, linux-rdma@...r.kernel.org,
        linux-rpi-kernel@...ts.infradead.org, linux-xfs@...r.kernel.org,
        netdev@...r.kernel.org, rds-devel@....oracle.com,
        sparclinux@...r.kernel.org, x86@...nel.org,
        xen-devel@...ts.xenproject.org, John Hubbard <jhubbard@...dia.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Kees Cook <keescook@...omium.org>,
        Rob Herring <robh@...nel.org>
Subject: [PATCH v3 21/41] fsl_hypervisor: convert put_page() to put_user_page*()

From: John Hubbard <jhubbard@...dia.com>

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page() or
release_pages().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
("mm: introduce put_user_page*(), placeholder versions").

This changes the release code slightly, because each page slot in the
page_list[] array is no longer checked for NULL. However, that check
was wrong anyway, because the get_user_pages() pattern of usage here
never allowed for NULL entries within a range of pinned pages.

Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Kees Cook <keescook@...omium.org>
Cc: Rob Herring <robh@...nel.org>
Signed-off-by: John Hubbard <jhubbard@...dia.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 93d5bebf9572..a8f78d572c45 100644
--- a/drivers/virt/fsl_hypervisor.c
+++ b/drivers/virt/fsl_hypervisor.c
@@ -292,11 +292,8 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
 		virt_to_phys(sg_list), num_pages);
 
 exit:
-	if (pages) {
-		for (i = 0; i < num_pages; i++)
-			if (pages[i])
-				put_page(pages[i]);
-	}
+	if (pages)
+		put_user_pages(pages, num_pages);
 
 	kfree(sg_list_unaligned);
 	kfree(pages);
-- 
2.22.0