From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Huaisheng Ye Subject: [PATCH 3/5] s390, dcssblk: Allow a NULL-kaddr to ->direct_access() Date: Tue, 24 Jul 2018 16:45:08 +0800 Message-Id: <20180724084510.6104-4-yehs2007@zoho.com> In-Reply-To: <20180724084510.6104-1-yehs2007@zoho.com> References: <20180724084510.6104-1-yehs2007@zoho.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Archive: List-Post: To: linux-nvdimm@lists.01.org, dan.j.williams@intel.com Cc: ross.zwisler@linux.intel.com, willy@infradead.org, vishal.l.verma@intel.com, dave.jiang@intel.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, viro@zeniv.linux.org.uk, martin.petersen@oracle.com, axboe@kernel.dk, gregkh@linuxfoundation.org, bart.vanassche@wdc.com, jack@suse.cz, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org, chengnt@lenovo.com, Huaisheng Ye List-ID: From: Huaisheng Ye dcssblk_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 --- drivers/s390/block/dcssblk.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c index 0a312e4..9c13dc5 100644 --- a/drivers/s390/block/dcssblk.c +++ b/drivers/s390/block/dcssblk.c @@ -915,7 +915,8 @@ static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show, unsigned long dev_sz; dev_sz = dev_info->end - dev_info->start + 1; - *kaddr = (void *) dev_info->start + offset; + if (kaddr) + *kaddr = (void *) dev_info->start + offset; *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), PFN_DEV|PFN_SPECIAL); -- 1.8.3.1