leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

saner calling conventions for csum_and_copy_..._user()

Browse Source 
All callers of these primitives will
	* discard anything we might've copied in case of error
	* ignore the csum value in case of error
	* always pass 0xffffffff as the initial sum, so the
resulting csum value (in case of success, that is) will never be 0.

That suggest the following calling conventions:
	* don't pass err_ptr - just return 0 on error.
	* don't bother with zeroing destination, etc. in case of error
	* don't pass the initial sum - just use 0xffffffff.

This commit does the minimal conversion in the instances of csum_and_copy_...();
the changes of actual asm code behind them are done later in the series.
Note that this asm code is often shared with csum_partial_copy_nocheck();
the difference is that csum_partial_copy_nocheck() passes 0 for initial
sum while csum_and_copy_..._user() pass 0xffffffff.  Fortunately, we are
free to pass 0xffffffff in all cases and subsequent patches will use that
freedom without any special comments.

A part that could be split off: parisc and uml/i386 claimed to have
csum_and_copy_to_user() instances of their own, but those were identical
to the generic one, so we simply drop them.  Not sure if it's worth
a separate commit...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2020-07-11 00:27:49 -04:00
parent 99a2c96d52
commit c693cc4676
19 changed files with 183 additions and 287 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
arch/arm/include/asm/checksum.h
View File

@@ -43,16 +43,15 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len, __wsum s
#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
#define _HAVE_ARCH_CSUM_AND_COPY
static inline
__wsum csum_and_copy_from_user (const void __user *src, void *dst,
int len, __wsum sum, int *err_ptr)
__wsum csum_and_copy_from_user(const void __user *src, void *dst, int len)
{
if (access_ok(src, len))
return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
int err = 0;
if (len)
*err_ptr = -EFAULT;
if (!access_ok(src, len))
return 0;
return sum;
sum = csum_partial_copy_from_user(src, dst, len, ~0U, &err);
return err ? 0 : sum;
}
/*