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rapidio: convert get_user_pages() --> pin_user_pages() 

This code was using get_user_pages_fast(), in a "Case 2" scenario
(DMA/RDMA), using the categorization from [1].  That means that it's time
to convert the get_user_pages_fast() + put_page() calls to
pin_user_pages_fast() + unpin_user_pages() calls.

There is some helpful background in [2]: basically, this is a small
part of fixing a long-standing disconnect between pinning pages, and
file systems' use of those pages.

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

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

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Alexandre Bounine <alex.bou9@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Link: http://lkml.kernel.org/r/20200517235620.205225-3-jhubbard@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
John Hubbard 2020-06-04 16:51:24 -07:00 committed by Linus Torvalds
parent e1c3cdb26a
commit 67446283d8
1 changed files with 5 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/rapidio/devices/rio_mport_cdev.c
View File

@ -572,14 +572,12 @@ static void dma_req_free(struct kref *ref)
struct mport_dma_req *req = container_of(ref, struct mport_dma_req,
refcount);
struct mport_cdev_priv *priv = req->priv;
unsigned int i;
dma_unmap_sg(req->dmach->device->dev,
req->sgt.sgl, req->sgt.nents, req->dir);
sg_free_table(&req->sgt);
if (req->page_list) {
for (i = 0; i < req->nr_pages; i++)
put_page(req->page_list[i]);
unpin_user_pages(req->page_list, req->nr_pages);
kfree(req->page_list);
}
@ -815,7 +813,7 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode,
struct mport_dma_req *req;
struct mport_dev *md = priv->md;
struct dma_chan *chan;
int i, ret;
int ret;
int nents;
if (xfer->length == 0)
@ -862,7 +860,7 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode,
goto err_req;
}
pinned = get_user_pages_fast(
pinned = pin_user_pages_fast(
(unsigned long)xfer->loc_addr & PAGE_MASK,
nr_pages,
dir == DMA_FROM_DEVICE ? FOLL_WRITE : 0,
@ -870,7 +868,7 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode,
if (pinned != nr_pages) {
if (pinned < 0) {
rmcd_error("get_user_pages_unlocked err=%ld",
rmcd_error("pin_user_pages_fast err=%ld",
pinned);
nr_pages = 0;
} else
@ -951,8 +949,7 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode,
err_pg:
if (!req->page_list) {
for (i = 0; i < nr_pages; i++)
put_page(page_list[i]);
unpin_user_pages(page_list, nr_pages);
kfree(page_list);
}
err_req: