From: Huaisheng Ye <[email protected]>

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 <[email protected]>
Signed-off-by: Huaisheng Ye <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
---
 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

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