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[v2,1/6] libnvdimm, pmem: kaddr and pfn can be NULL to ->direct_access()

Message ID 20180725162849.8320-2-yehs2007@zoho.com (mailing list archive)
State New, archived
Headers show
Series kaddr and pfn can be NULL to ->direct_access() | expand

Commit Message

Huaisheng Ye July 25, 2018, 4:28 p.m. UTC 
From: Huaisheng Ye <yehs1@lenovo.com>

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 pointer or local variable that
they then just throw away.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
---
 drivers/nvdimm/pmem.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
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Patch

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 8b1fd7f..ecf9024 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -227,8 +227,11 @@  __weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 	if (unlikely(is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) / 512,
 					PFN_PHYS(nr_pages))))
 		return -EIO;
-	*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