linux-kernel - [PATCH AUTOSEL 4.18 065/131] tools/testing/nvdimm: kaddr and pfn can be NULL to ->direct

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Date:   Sun, 2 Sep 2018 13:04:23 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Huaisheng Ye <yehs1@...ovo.com>, Dave Jiang <dave.jiang@...el.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.18 065/131] tools/testing/nvdimm: kaddr and pfn can
 be NULL to ->direct_access()

From: Huaisheng Ye <yehs1@...ovo.com>

[ Upstream commit 45df5d3dc0c7289c1e67afe6d2ba806ad5174314 ]

The mock / test version of pmem_direct_access() needs to check the
validity of pointers kaddr and pfn for NULL assignment. If anyone
equals to NULL, it doesn't need to calculate the value.

If pointer equals to NULL, that is to say callers may have no need for
kaddr or pfn, so this patch is prepared for allowing them to pass in
NULL instead of having to pass in a local pointer or variable that
they then just throw away.

Suggested-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Huaisheng Ye <yehs1@...ovo.com>
Reviewed-by: Ross Zwisler <ross.zwisler@...ux.intel.com>
Signed-off-by: Dave Jiang <dave.jiang@...el.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 tools/testing/nvdimm/pmem-dax.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/tools/testing/nvdimm/pmem-dax.c b/tools/testing/nvdimm/pmem-dax.c
index b53596ad601b..2e7fd8227969 100644
--- a/tools/testing/nvdimm/pmem-dax.c
+++ b/tools/testing/nvdimm/pmem-dax.c
@@ -31,17 +31,21 @@ long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 	if (get_nfit_res(pmem->phys_addr + offset)) {
 		struct page *page;
 
-		*kaddr = pmem->virt_addr + offset;
+		if (kaddr)
+			*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));
 
 		return 1;
 	}
 
-	*kaddr = pmem->virt_addr + offset;
-	*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
+	if (kaddr)
+		*kaddr = pmem->virt_addr + offset;
+	if (pfn)
+		*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
 
 	/*
 	 * If badblocks are present, limit known good range to the
-- 
2.17.1