linux-kernel - [PATCH 1/5] libnvdimm, pmem: Allow a NULL-kaddr to ->direct

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Message-Id: <20180724084510.6104-2-yehs2007@zoho.com>
Date:   Tue, 24 Jul 2018 16:45:06 +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, linux-kernel@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        chengnt@...ovo.com, Huaisheng Ye <yehs1@...ovo.com>
Subject: [PATCH 1/5] libnvdimm, pmem: Allow a NULL-kaddr to ->direct_access()

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

pmem_direct_access() needs to check the validity of second rank
pointer kaddr for NULL assignment. If kaddr equals to NULL, it
doesn't need to calculate the value.

Signed-off-by: Huaisheng Ye <yehs1@...ovo.com>
---
 drivers/nvdimm/pmem.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 9d71492..b1d121a 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -232,7 +232,9 @@ __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;
+
+	if (kaddr)
+		*kaddr = pmem->virt_addr + offset;
 	*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
 
 	/*
-- 
1.8.3.1