linux-kernel - [PATCH v3 3/4] staging: kpc2000: kpc_dma: Convert get_user_pages() --> pin_user

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Date:   Wed,  1 Jul 2020 11:47:43 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     gregkh@...uxfoundation.org, jane.pnx9@...il.com,
        daniel.m.jordan@...cle.com, simon@...anor.nu,
        harshjain32@...il.com, pakki001@....edu
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Souptick Joarder <jrdr.linux@...il.com>,
        John Hubbard <jhubbard@...dia.com>,
        Bharath Vedartham <linux.bhar@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH v3 3/4] staging: kpc2000: kpc_dma: Convert get_user_pages() -->  pin_user_pages()

In 2019, we introduced pin_user_pages*() and now we are converting
get_user_pages*() to the new API as appropriate. [1] & [2] could
be referred for more information. This is case 2 as per document [1].

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
        https://lwn.net/Articles/807108/

Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
Cc: John Hubbard <jhubbard@...dia.com>
Cc: Bharath Vedartham <linux.bhar@...il.com>
Cc: Dan Carpenter <dan.carpenter@...cle.com>
---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
index 08d90a6..8cd20ad 100644
--- a/drivers/staging/kpc2000/kpc_dma/fileops.c
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -76,10 +76,10 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 
 	// Lock the user buffer pages in memory, and hold on to the page pointers (for the sglist)
 	mmap_read_lock(current->mm);      /*  get memory map semaphore */
-	rv = get_user_pages(iov_base, acd->page_count, FOLL_TOUCH | FOLL_WRITE | FOLL_GET, acd->user_pages, NULL);
+	rv = pin_user_pages(iov_base, acd->page_count, FOLL_TOUCH | FOLL_WRITE, acd->user_pages, NULL);
 	mmap_read_unlock(current->mm);        /*  release the semaphore */
 	if (rv != acd->page_count) {
-		dev_err(&priv->ldev->pldev->dev, "Couldn't get_user_pages (%d)\n", rv);
+		dev_err(&priv->ldev->pldev->dev, "Couldn't pin_user_pages (%d)\n", rv);
 		goto err_get_user_pages;
 	}
 
@@ -189,13 +189,11 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 	sg_free_table(&acd->sgt);
  err_dma_map_sg:
  err_alloc_sg_table:
-	for (i = 0 ; i < acd->page_count ; i++)
-		put_page(acd->user_pages[i]);
+	unpin_user_pages(acd->user_pages, acd->page_count);
 
  err_get_user_pages:
 	if (rv > 0) {
-		for (i = 0; i < rv; i++)
-			put_pages(acd->user_pages[i]);
+		unpin_user_pages(acd->user_pages, rv);
 		rv = -EFAULT;
 	}
 	kfree(acd->user_pages);
@@ -222,8 +220,7 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
 			set_page_dirty_lock(acd->user_pages[i]);
 	}
 
-	for (i = 0 ; i < acd->page_count ; i++)
-		put_page(acd->user_pages[i]);
+	unpin_user_pages(acd->user_pages, acd->page_count);
 
 	sg_free_table(&acd->sgt);
 
-- 
1.9.1