From 036a82ca90328960d66b7a5c0e1908475d534d62 Mon Sep 17 00:00:00 2001
From: Huaisheng Ye <yehs1@lenovo.com>
Date: Mon, 30 Jul 2018 15:15:44 +0800
Subject: [PATCH] s390, dcssblk: kaddr and pfn can be NULL to ->direct_access()
References: bsc#1174873
Git-commit: 036a82ca90328960d66b7a5c0e1908475d534d62
Patch-mainline: v4.19-rc1
dcssblk_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 either of them is equal 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>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Dave Jiang <dave.jianig@intel.com>
Signed-off-by: Thomas Abraham <tabraham@suse.com>
---
drivers/s390/block/dcssblk.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index ed607288e696..23e526cda5c1 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -922,9 +922,11 @@ __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
unsigned long dev_sz;
dev_sz = dev_info->end - dev_info->start + 1;
- *kaddr = (void *) dev_info->start + offset;
- *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
- PFN_DEV|PFN_SPECIAL);
+ if (kaddr)
+ *kaddr = (void *) dev_info->start + offset;
+ if (pfn)
+ *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
+ PFN_DEV|PFN_SPECIAL);
return (dev_sz - offset) / PAGE_SIZE;
}
--
2.26.2