[PATCH 3/5] s390, dcssblk: Allow a NULL-kaddr to ->direct_access()

Huaisheng Ye
2018-07-24T08:45:08Z

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 <yehs1@lenovo.com>
---
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