fpga: dfl: afu: convert get_user_pages() --> pin_user_pages() (55dc9b87) · Commits · 戴 / test

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/ Cc: Xu Yilun <yilun.xu@intel.com> Cc: Wu Hao <hao.wu@intel.com> Cc: Moritz Fischer <mdf@kernel.org> Cc: linux-fpga@vger.kernel.org Signed-off-by:

John Hubbard <jhubbard@nvidia.com> Acked-by:

Wu Hao <hao.wu@intel.com> Signed-off-by:

Moritz Fischer <mdf@kernel.org>

drivers/fpga/dfl-afu-dma-region.c

+5 −14

Original line number	Diff line number	Diff line
		@@ -16,15 +16,6 @@

		#include "dfl-afu.h"

		static void put_all_pages(struct page **pages, int npages)
		{
		int i;

		for (i = 0; i < npages; i++)
		if (pages[i])
		put_page(pages[i]);
		}

		void afu_dma_region_init(struct dfl_feature_platform_data *pdata)
		{
		struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
		@@ -57,22 +48,22 @@ static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata,
		goto unlock_vm;
		}

		pinned = get_user_pages_fast(region->user_addr, npages, FOLL_WRITE,
		pinned = pin_user_pages_fast(region->user_addr, npages, FOLL_WRITE,
		region->pages);
		if (pinned < 0) {
		ret = pinned;
		goto free_pages;
		} else if (pinned != npages) {
		ret = -EFAULT;
		goto put_pages;
		goto unpin_pages;
		}

		dev_dbg(dev, "%d pages pinned\n", pinned);

		return 0;

		put_pages:
		put_all_pages(region->pages, pinned);
		unpin_pages:
		unpin_user_pages(region->pages, pinned);
		free_pages:
		kfree(region->pages);
		unlock_vm:
		@@ -94,7 +85,7 @@ static void afu_dma_unpin_pages(struct dfl_feature_platform_data *pdata,
		long npages = region->length >> PAGE_SHIFT;
		struct device *dev = &pdata->dev->dev;

		put_all_pages(region->pages, npages);
		unpin_user_pages(region->pages, npages);
		kfree(region->pages);
		account_locked_vm(current->mm, npages, false);

Admin message