Commit ddae1423 authored by John Hubbard's avatar John Hubbard Committed by Greg Kroah-Hartman
Browse files

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

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



Cc: Frank Haverkamp <haver@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Link: https://lore.kernel.org/r/20200518015237.1568940-1-jhubbard@nvidia.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5459ceed

drivers/misc/genwqe/card_utils.c

+9 −33
Original line number Diff line number Diff line
@@ -514,30 +514,6 @@ int genwqe_free_sync_sgl(struct genwqe_dev *cd, struct genwqe_sgl *sgl) 
	return rc;

}



/**

 * genwqe_free_user_pages() - Give pinned pages back

 *

 * Documentation of get_user_pages is in mm/gup.c:

 *

 * If the page is written to, set_page_dirty (or set_page_dirty_lock,

 * as appropriate) must be called after the page is finished with, and

 * before put_page is called.

 */

static int genwqe_free_user_pages(struct page **page_list,

			unsigned int nr_pages, int dirty)

{

	unsigned int i;



	for (i = 0; i < nr_pages; i++) {

		if (page_list[i] != NULL) {

			if (dirty)

				set_page_dirty_lock(page_list[i]);

			put_page(page_list[i]);

		}

	}

	return 0;

}



/**

 * genwqe_user_vmap() - Map user-space memory to virtual kernel memory

 * @cd:         pointer to genwqe device
@@ -597,18 +573,18 @@ int genwqe_user_vmap(struct genwqe_dev *cd, struct dma_mapping *m, void *uaddr, 
	m->dma_list = (dma_addr_t *)(m->page_list + m->nr_pages);



	/* pin user pages in memory */

	rc = get_user_pages_fast(data & PAGE_MASK, /* page aligned addr */

	rc = pin_user_pages_fast(data & PAGE_MASK, /* page aligned addr */

				 m->nr_pages,

				 m->write ? FOLL_WRITE : 0,	/* readable/writable */

				 m->page_list);	/* ptrs to pages */

	if (rc < 0)

		goto fail_get_user_pages;

		goto fail_pin_user_pages;



	/* assumption: get_user_pages can be killed by signals. */

	/* assumption: pin_user_pages can be killed by signals. */

	if (rc < m->nr_pages) {

		genwqe_free_user_pages(m->page_list, rc, m->write);

		unpin_user_pages_dirty_lock(m->page_list, rc, m->write);

		rc = -EFAULT;

		goto fail_get_user_pages;

		goto fail_pin_user_pages;

	}



	rc = genwqe_map_pages(cd, m->page_list, m->nr_pages, m->dma_list);
@@ -618,9 +594,9 @@ int genwqe_user_vmap(struct genwqe_dev *cd, struct dma_mapping *m, void *uaddr, 
	return 0;



 fail_free_user_pages:

	genwqe_free_user_pages(m->page_list, m->nr_pages, m->write);

	unpin_user_pages_dirty_lock(m->page_list, m->nr_pages, m->write);



 fail_get_user_pages:

 fail_pin_user_pages:

	kfree(m->page_list);

	m->page_list = NULL;

	m->dma_list = NULL;
@@ -650,8 +626,8 @@ int genwqe_user_vunmap(struct genwqe_dev *cd, struct dma_mapping *m) 
		genwqe_unmap_pages(cd, m->dma_list, m->nr_pages);



	if (m->page_list) {

		genwqe_free_user_pages(m->page_list, m->nr_pages, m->write);



		unpin_user_pages_dirty_lock(m->page_list, m->nr_pages,

					    m->write);

		kfree(m->page_list);

		m->page_list = NULL;

		m->dma_list = NULL;

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