linux-kernel - [PATCH v3 3/6] tools/testing/nvdimm: kaddr and pfn can be NULL to ->direct

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Message-Id: <20180730071548.9172-4-yehs2007@zoho.com>
Date:   Mon, 30 Jul 2018 15:15:45 +0800
From:   Huaisheng Ye <yehs2007@...o.com>
To:     linux-nvdimm@...ts.01.org, dan.j.williams@...el.com
Cc:     ross.zwisler@...ux.intel.com, willy@...radead.org,
        vishal.l.verma@...el.com, dave.jiang@...el.com,
        schwidefsky@...ibm.com, heiko.carstens@...ibm.com,
        viro@...iv.linux.org.uk, martin.petersen@...cle.com,
        axboe@...nel.dk, gregkh@...uxfoundation.org,
        bart.vanassche@....com, jack@...e.cz, agk@...hat.com,
        snitzer@...hat.com, keescook@...omium.org, dm-devel@...hat.com,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, colyli@...e.de, chengnt@...ovo.com,
        Huaisheng Ye <yehs1@...ovo.com>
Subject: [PATCH v3 3/6] tools/testing/nvdimm: kaddr and pfn can be NULL to ->direct_access()

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

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>
---
 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 b53596a..2e7fd82 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
-- 
1.8.3.1