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Subject: [PATCH v2 08/14] tools/testing/nvdimm: Allow a NULL-pfn to
 ->direct_access()
From:   Dan Williams <dan.j.williams@intel.com>
To:     akpm@linux-foundation.org
Cc:     Huaisheng Ye <yehs1@lenovo.com>, Jan Kara <jack@suse.cz>,
        vishal.l.verma@intel.com, hch@lst.de, linux-mm@kvack.org,
        jack@suse.cz, linux-nvdimm@lists.01.org,
        linux-kernel@vger.kernel.org
Date:   Mon, 16 Jul 2018 10:01:03 -0700
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From: Huaisheng Ye <yehs1@lenovo.com>

The mock / test version of pmem_direct_access() needs to check the
validity of pointer pfn for NULL assignment. If pfn equals to NULL, it
doesn't need to calculate the value. This is in support of asynchronous
memmap init and avoid page lookups when possible.

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 tools/testing/nvdimm/pmem-dax.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/testing/nvdimm/pmem-dax.c b/tools/testing/nvdimm/pmem-dax.c
index b53596ad601b..d4cb5281b30e 100644
--- a/tools/testing/nvdimm/pmem-dax.c
+++ b/tools/testing/nvdimm/pmem-dax.c
@@ -33,7 +33,8 @@ long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 
 		*kaddr = pmem->virt_addr + offset;
 		page = vmalloc_to_page(pmem->virt_addr + offset);
-		*pfn = page_to_pfn_t(page);
+		if (pfn)
+			*pfn = page_to_pfn_t(page);
 		pr_debug_ratelimited("%s: pmem: %p pgoff: %#lx pfn: %#lx\n",
 				__func__, pmem, pgoff, page_to_pfn(page));
 
@@ -41,7 +42,8 @@ long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 	}
 
 	*kaddr = pmem->virt_addr + offset;
-	*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
+	if (pfn)
+		*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
 
 	/*
 	 * If badblocks are present, limit known good range to the