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s390, dcssblk: kaddr and pfn can be NULL to ->direct_access() 

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>
zero-colors
Huaisheng Ye 2018-07-30 15:15:44 +08:00 committed by Dave Jiang
parent 46a590cde0
commit 036a82ca90
1 changed files with 5 additions and 3 deletions
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8
drivers/s390/block/dcssblk.c
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@ -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;
}