From: Al Viro <v...@zeniv.linux.org.uk>

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 <v...@zeniv.linux.org.uk>
---
 arch/alpha/include/asm/checksum.h    |  2 +-
 arch/alpha/lib/csum_partial_copy.c   | 25 ++++++-------
 arch/arm/include/asm/checksum.h      | 13 ++++---
 arch/m68k/include/asm/checksum.h     |  3 +-
 arch/m68k/lib/checksum.c             |  8 ++---
 arch/mips/include/asm/checksum.h     | 46 ++++++++++++------------
 arch/parisc/include/asm/checksum.h   | 20 -----------
 arch/powerpc/include/asm/checksum.h  |  4 +--
 arch/powerpc/lib/checksum_wrappers.c | 68 +++++++++++-------------------------
 arch/sh/include/asm/checksum_32.h    | 36 +++++++++----------
 arch/sparc/include/asm/checksum_32.h | 65 ++++++++++++++++------------------
 arch/sparc/include/asm/checksum_64.h | 14 ++++----
 arch/x86/include/asm/checksum_32.h   | 35 ++++++++-----------
 arch/x86/include/asm/checksum_64.h   |  6 ++--
 arch/x86/lib/csum-wrappers_64.c      | 38 +++++++++-----------
 arch/x86/um/asm/checksum_32.h        | 23 ------------
 arch/xtensa/include/asm/checksum.h   | 30 ++++++++--------
 include/net/checksum.h               | 15 ++++----
 lib/iov_iter.c                       | 19 +++++-----
 19 files changed, 183 insertions(+), 287 deletions(-)

diff --git a/arch/alpha/include/asm/checksum.h 
b/arch/alpha/include/asm/checksum.h
index fdb301fd819b..f8659ae21134 100644
--- a/arch/alpha/include/asm/checksum.h
+++ b/arch/alpha/include/asm/checksum.h
@@ -42,7 +42,7 @@ extern __wsum csum_partial(const void *buff, int len, __wsum 
sum);
  * better 64-bit) boundary
  */
 #define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
-__wsum csum_and_copy_from_user(const void __user *src, void *dst, int len, 
__wsum sum, int *errp);
+__wsum csum_and_copy_from_user(const void __user *src, void *dst, int len);
 
 __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len);
 
diff --git a/arch/alpha/lib/csum_partial_copy.c 
b/arch/alpha/lib/csum_partial_copy.c
index f363dc89fcbe..3c0e89c39ddb 100644
--- a/arch/alpha/lib/csum_partial_copy.c
+++ b/arch/alpha/lib/csum_partial_copy.c
@@ -325,30 +325,27 @@ csum_partial_cfu_unaligned(const unsigned long __user * 
src,
 }
 
 __wsum
-csum_and_copy_from_user(const void __user *src, void *dst, int len,
-                              __wsum sum, int *errp)
+csum_and_copy_from_user(const void __user *src, void *dst, int len)
 {
-       unsigned long checksum = (__force u32) sum;
+       unsigned long checksum = ~0U;
        unsigned long soff = 7 & (unsigned long) src;
        unsigned long doff = 7 & (unsigned long) dst;
+       int err = 0;
 
        if (len) {
-               if (!access_ok(src, len)) {
-                       if (errp) *errp = -EFAULT;
-                       memset(dst, 0, len);
-                       return sum;
-               }
+               if (!access_ok(src, len))
+                       return 0;
                if (!doff) {
                        if (!soff)
                                checksum = csum_partial_cfu_aligned(
                                        (const unsigned long __user *) src,
                                        (unsigned long *) dst,
-                                       len-8, checksum, errp);
+                                       len-8, checksum, &err);
                        else
                                checksum = csum_partial_cfu_dest_aligned(
                                        (const unsigned long __user *) src,
                                        (unsigned long *) dst,
-                                       soff, len-8, checksum, errp);
+                                       soff, len-8, checksum, &err);
                } else {
                        unsigned long partial_dest;
                        ldq_u(partial_dest, dst);
@@ -357,15 +354,15 @@ csum_and_copy_from_user(const void __user *src, void 
*dst, int len,
                                        (const unsigned long __user *) src,
                                        (unsigned long *) dst,
                                        doff, len-8, checksum,
-                                       partial_dest, errp);
+                                       partial_dest, &err);
                        else
                                checksum = csum_partial_cfu_unaligned(
                                        (const unsigned long __user *) src,
                                        (unsigned long *) dst,
                                        soff, doff, len-8, checksum,
-                                       partial_dest, errp);
+                                       partial_dest, &err);
                }
-               checksum = from64to16 (checksum);
+               checksum = err ? 0 : from64to16 (checksum);
        }
        return (__force __wsum)checksum;
 }
@@ -378,7 +375,7 @@ csum_partial_copy_nocheck(const void *src, void *dst, int 
len)
        mm_segment_t oldfs = get_fs();
        set_fs(KERNEL_DS);
        checksum = csum_and_copy_from_user((__force const void __user *)src,
-                                               dst, len, 0, NULL);
+                                               dst, len);
        set_fs(oldfs);
        return checksum;
 }
diff --git a/arch/arm/include/asm/checksum.h b/arch/arm/include/asm/checksum.h
index 1156b9a9a43b..737db6c3c482 100644
--- a/arch/arm/include/asm/checksum.h
+++ b/arch/arm/include/asm/checksum.h
@@ -42,16 +42,15 @@ csum_partial_copy_from_user(const void __user *src, void 
*dst, int len, __wsum s
 
 #define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 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;
 }
 
 /*
diff --git a/arch/m68k/include/asm/checksum.h b/arch/m68k/include/asm/checksum.h
index 77c61473ee0f..4e13ad046291 100644
--- a/arch/m68k/include/asm/checksum.h
+++ b/arch/m68k/include/asm/checksum.h
@@ -33,8 +33,7 @@ __wsum csum_partial(const void *buff, int len, __wsum sum);
 #define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 extern __wsum csum_and_copy_from_user(const void __user *src,
                                                void *dst,
-                                               int len, __wsum sum,
-                                               int *csum_err);
+                                               int len);
 
 extern __wsum csum_partial_copy_nocheck(const void *src,
                                              void *dst, int len);
diff --git a/arch/m68k/lib/checksum.c b/arch/m68k/lib/checksum.c
index 86ddd2ee187d..3aeca261f622 100644
--- a/arch/m68k/lib/checksum.c
+++ b/arch/m68k/lib/checksum.c
@@ -129,8 +129,7 @@ EXPORT_SYMBOL(csum_partial);
  */
 
 __wsum
-csum_and_copy_from_user(const void __user *src, void *dst,
-                           int len, __wsum sum, int *csum_err)
+csum_and_copy_from_user(const void __user *src, void *dst, int len)
 {
        /*
         * GCC doesn't like more than 10 operands for the asm
@@ -138,6 +137,7 @@ csum_and_copy_from_user(const void __user *src, void *dst,
         * code.
         */
        unsigned long tmp1, tmp2;
+       __wsum sum = ~0U;
 
        __asm__("movel %2,%4\n\t"
                "btst #1,%4\n\t"        /* Check alignment */
@@ -311,9 +311,7 @@ csum_and_copy_from_user(const void __user *src, void *dst,
                : "0" (sum), "1" (len), "2" (src), "3" (dst)
            );
 
-       *csum_err = tmp2;
-
-       return(sum);
+       return tmp2 ? 0 : sum;
 }
 
 EXPORT_SYMBOL(csum_and_copy_from_user);
diff --git a/arch/mips/include/asm/checksum.h b/arch/mips/include/asm/checksum.h
index 1dcdd7755793..1e5558f90126 100644
--- a/arch/mips/include/asm/checksum.h
+++ b/arch/mips/include/asm/checksum.h
@@ -60,16 +60,15 @@ __wsum csum_partial_copy_from_user(const void __user *src, 
void *dst, int len,
 
 #define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 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);
-       if (len)
-               *err_ptr = -EFAULT;
+       __wsum sum = ~0U;
+       int err = 0;
 
-       return sum;
+       if (!access_ok(src, len))
+               return 0;
+       sum = csum_partial_copy_from_user(src, dst, len, sum, &err);
+       return err ? 0 : sum;
 }
 
 /*
@@ -77,24 +76,23 @@ __wsum csum_and_copy_from_user(const void __user *src, void 
*dst,
  */
 #define HAVE_CSUM_COPY_USER
 static inline
-__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
-                            __wsum sum, int *err_ptr)
+__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len)
 {
+       int err = 0;
+       __wsum sum = ~0U;
+
        might_fault();
-       if (access_ok(dst, len)) {
-               if (uaccess_kernel())
-                       return __csum_partial_copy_kernel(src,
-                                                         (__force void *)dst,
-                                                         len, sum, err_ptr);
-               else
-                       return __csum_partial_copy_to_user(src,
-                                                          (__force void *)dst,
-                                                          len, sum, err_ptr);
-       }
-       if (len)
-               *err_ptr = -EFAULT;
-
-       return (__force __wsum)-1; /* invalid checksum */
+       if (!access_ok(dst, len))
+               return 0;
+       if (uaccess_kernel())
+               sum = __csum_partial_copy_kernel(src,
+                                                 (__force void *)dst,
+                                                 len, sum, &err);
+       else
+               sum = __csum_partial_copy_to_user(src,
+                                                  (__force void *)dst,
+                                                  len, sum, &err);
+       return err ? 0 : sum;
 }
 
 /*
diff --git a/arch/parisc/include/asm/checksum.h 
b/arch/parisc/include/asm/checksum.h
index b412e3a1bd14..44c1b4836fb5 100644
--- a/arch/parisc/include/asm/checksum.h
+++ b/arch/parisc/include/asm/checksum.h
@@ -181,25 +181,5 @@ static __inline__ __sum16 csum_ipv6_magic(const struct 
in6_addr *saddr,
        return csum_fold(sum);
 }
 
-/* 
- *     Copy and checksum to user
- */
-#define HAVE_CSUM_COPY_USER
-static __inline__ __wsum csum_and_copy_to_user(const void *src,
-                                                     void __user *dst,
-                                                     int len, __wsum sum,
-                                                     int *err_ptr)
-{
-       /* code stolen from include/asm-mips64 */
-       sum = csum_partial(src, len, sum);
-        
-       if (copy_to_user(dst, src, len)) {
-               *err_ptr = -EFAULT;
-               return (__force __wsum)-1;
-       }
-
-       return sum;
-}
-
 #endif
 
diff --git a/arch/powerpc/include/asm/checksum.h 
b/arch/powerpc/include/asm/checksum.h
index 40540b7242a3..97343e1a7d1c 100644
--- a/arch/powerpc/include/asm/checksum.h
+++ b/arch/powerpc/include/asm/checksum.h
@@ -24,10 +24,10 @@ extern __wsum csum_partial_copy_generic(const void *src, 
void *dst,
 
 #define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 extern __wsum csum_and_copy_from_user(const void __user *src, void *dst,
-                                     int len, __wsum sum, int *err_ptr);
+                                     int len);
 #define HAVE_CSUM_COPY_USER
 extern __wsum csum_and_copy_to_user(const void *src, void __user *dst,
-                                   int len, __wsum sum, int *err_ptr);
+                                   int len);
 
 #define csum_partial_copy_nocheck(src, dst, len)   \
         csum_partial_copy_generic((src), (dst), (len), 0, NULL, NULL)
diff --git a/arch/powerpc/lib/checksum_wrappers.c 
b/arch/powerpc/lib/checksum_wrappers.c
index fabe4db28726..b1faa82dd8af 100644
--- a/arch/powerpc/lib/checksum_wrappers.c
+++ b/arch/powerpc/lib/checksum_wrappers.c
@@ -12,82 +12,56 @@
 #include <linux/uaccess.h>
 
 __wsum csum_and_copy_from_user(const void __user *src, void *dst,
-                              int len, __wsum sum, int *err_ptr)
+                              int len)
 {
        unsigned int csum;
+       int err = 0;
 
        might_sleep();
-       allow_read_from_user(src, len);
-
-       *err_ptr = 0;
 
-       if (!len) {
-               csum = 0;
-               goto out;
-       }
+       if (unlikely(!access_ok(src, len)))
+               return 0;
 
-       if (unlikely((len < 0) || !access_ok(src, len))) {
-               *err_ptr = -EFAULT;
-               csum = (__force unsigned int)sum;
-               goto out;
-       }
+       allow_read_from_user(src, len);
 
        csum = csum_partial_copy_generic((void __force *)src, dst,
-                                        len, sum, err_ptr, NULL);
+                                        len, ~0U, &err, NULL);
 
-       if (unlikely(*err_ptr)) {
+       if (unlikely(err)) {
                int missing = __copy_from_user(dst, src, len);
 
-               if (missing) {
-                       memset(dst + len - missing, 0, missing);
-                       *err_ptr = -EFAULT;
-               } else {
-                       *err_ptr = 0;
-               }
-
-               csum = csum_partial(dst, len, sum);
+               if (missing)
+                       csum = 0;
+               else
+                       csum = csum_partial(dst, len, ~0U);
        }
 
-out:
        prevent_read_from_user(src, len);
        return (__force __wsum)csum;
 }
 EXPORT_SYMBOL(csum_and_copy_from_user);
 
-__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
-                            __wsum sum, int *err_ptr)
+__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len)
 {
        unsigned int csum;
+       int err = 0;
 
        might_sleep();
-       allow_write_to_user(dst, len);
-
-       *err_ptr = 0;
-
-       if (!len) {
-               csum = 0;
-               goto out;
-       }
+       if (unlikely(!access_ok(dst, len)))
+               return 0;
 
-       if (unlikely((len < 0) || !access_ok(dst, len))) {
-               *err_ptr = -EFAULT;
-               csum = -1; /* invalid checksum */
-               goto out;
-       }
+       allow_write_to_user(dst, len);
 
        csum = csum_partial_copy_generic(src, (void __force *)dst,
-                                        len, sum, NULL, err_ptr);
+                                        len, ~0U, NULL, &err);
 
-       if (unlikely(*err_ptr)) {
-               csum = csum_partial(src, len, sum);
+       if (unlikely(err)) {
+               csum = csum_partial(src, len, ~0U);
 
-               if (copy_to_user(dst, src, len)) {
-                       *err_ptr = -EFAULT;
-                       csum = -1; /* invalid checksum */
-               }
+               if (copy_to_user(dst, src, len))
+                       csum = 0;
        }
 
-out:
        prevent_write_to_user(dst, len);
        return (__force __wsum)csum;
 }
diff --git a/arch/sh/include/asm/checksum_32.h 
b/arch/sh/include/asm/checksum_32.h
index 682f88ebb7de..97950bdf62e5 100644
--- a/arch/sh/include/asm/checksum_32.h
+++ b/arch/sh/include/asm/checksum_32.h
@@ -49,15 +49,16 @@ __wsum csum_partial_copy_nocheck(const void *src, void 
*dst, int len)
 
 #define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 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_generic((__force const void *)src, dst,
-                                       len, sum, err_ptr, NULL);
-       if (len)
-               *err_ptr = -EFAULT;
-       return sum;
+       int err = 0;
+       __wsum sum = ~0U;
+
+       if (!access_ok(src, len))
+               return 0;
+       sum = csum_partial_copy_generic((__force const void *)src, dst,
+                                       len, sum, &err, NULL);
+       return err ? 0 : sum;
 }
 
 /*
@@ -198,16 +199,15 @@ static inline __sum16 csum_ipv6_magic(const struct 
in6_addr *saddr,
 #define HAVE_CSUM_COPY_USER
 static inline __wsum csum_and_copy_to_user(const void *src,
                                           void __user *dst,
-                                          int len, __wsum sum,
-                                          int *err_ptr)
+                                          int len)
 {
-       if (access_ok(dst, len))
-               return csum_partial_copy_generic((__force const void *)src,
-                                               dst, len, sum, NULL, err_ptr);
-
-       if (len)
-               *err_ptr = -EFAULT;
-
-       return (__force __wsum)-1; /* invalid checksum */
+       int err = 0;
+       __wsum sum = ~0U;
+
+       if (!access_ok(dst, len))
+               return 0;
+       sum = csum_partial_copy_generic((__force const void *)src,
+                                               dst, len, sum, NULL, &err);
+       return err ? 0 : sum;
 }
 #endif /* __ASM_SH_CHECKSUM_H */
diff --git a/arch/sparc/include/asm/checksum_32.h 
b/arch/sparc/include/asm/checksum_32.h
index d21d114436ba..b5873b7b7bf0 100644
--- a/arch/sparc/include/asm/checksum_32.h
+++ b/arch/sparc/include/asm/checksum_32.h
@@ -60,19 +60,16 @@ csum_partial_copy_nocheck(const void *src, void *dst, int 
len)
 }
 
 static inline __wsum
-csum_and_copy_from_user(const void __user *src, void *dst, int len,
-                           __wsum sum, int *err)
+csum_and_copy_from_user(const void __user *src, void *dst, int len)
   {
        register unsigned long ret asm("o0") = (unsigned long)src;
        register char *d asm("o1") = dst;
        register int l asm("g1") = len;
-       register __wsum s asm("g7") = sum;
+       register __wsum s asm("g7") = ~0U;
+       int err = 0;
 
-       if (unlikely(!access_ok(src, len))) {
-               if (len)
-                       *err = -EFAULT;
-               return sum;
-       }
+       if (unlikely(!access_ok(src, len)))
+               return 0;
 
        __asm__ __volatile__ (
        ".section __ex_table,#alloc\n\t"
@@ -83,42 +80,40 @@ csum_and_copy_from_user(const void __user *src, void *dst, 
int len,
        "call __csum_partial_copy_sparc_generic\n\t"
        " st %8, [%%sp + 64]\n"
        : "=&r" (ret), "=&r" (d), "=&r" (l), "=&r" (s)
-       : "0" (ret), "1" (d), "2" (l), "3" (s), "r" (err)
+       : "0" (ret), "1" (d), "2" (l), "3" (s), "r" (&err)
        : "o2", "o3", "o4", "o5", "o7", "g2", "g3", "g4", "g5",
          "cc", "memory");
-       return (__force __wsum)ret;
+       return err ? 0 : (__force __wsum)ret;
 }
 
 #define HAVE_CSUM_COPY_USER
 
 static inline __wsum
-csum_and_copy_to_user(const void *src, void __user *dst, int len,
-                         __wsum sum, int *err)
+csum_and_copy_to_user(const void *src, void __user *dst, int len)
 {
-       if (!access_ok(dst, len)) {
-               *err = -EFAULT;
-               return sum;
-       } else {
-               register unsigned long ret asm("o0") = (unsigned long)src;
-               register char __user *d asm("o1") = dst;
-               register int l asm("g1") = len;
-               register __wsum s asm("g7") = sum;
+       register unsigned long ret asm("o0") = (unsigned long)src;
+       register char __user *d asm("o1") = dst;
+       register int l asm("g1") = len;
+       register __wsum s asm("g7") = ~0U;
+       int err = 0;
 
-               __asm__ __volatile__ (
-               ".section __ex_table,#alloc\n\t"
-               ".align 4\n\t"
-               ".word 1f,1\n\t"
-               ".previous\n"
-               "1:\n\t"
-               "call __csum_partial_copy_sparc_generic\n\t"
-               " st %8, [%%sp + 64]\n"
-               : "=&r" (ret), "=&r" (d), "=&r" (l), "=&r" (s)
-               : "0" (ret), "1" (d), "2" (l), "3" (s), "r" (err)
-               : "o2", "o3", "o4", "o5", "o7",
-                 "g2", "g3", "g4", "g5",
-                 "cc", "memory");
-               return (__force __wsum)ret;
-       }
+       if (!access_ok(dst, len))
+               return 0;
+
+       __asm__ __volatile__ (
+       ".section __ex_table,#alloc\n\t"
+       ".align 4\n\t"
+       ".word 1f,1\n\t"
+       ".previous\n"
+       "1:\n\t"
+       "call __csum_partial_copy_sparc_generic\n\t"
+       " st %8, [%%sp + 64]\n"
+       : "=&r" (ret), "=&r" (d), "=&r" (l), "=&r" (s)
+       : "0" (ret), "1" (d), "2" (l), "3" (s), "r" (&err)
+       : "o2", "o3", "o4", "o5", "o7",
+         "g2", "g3", "g4", "g5",
+         "cc", "memory");
+       return err ? 0 : (__force __wsum)ret;
 }
 
 /* ihl is always 5 or greater, almost always is 5, and iph is word aligned
diff --git a/arch/sparc/include/asm/checksum_64.h 
b/arch/sparc/include/asm/checksum_64.h
index 7aebdbe3ac96..4d0bbff43e62 100644
--- a/arch/sparc/include/asm/checksum_64.h
+++ b/arch/sparc/include/asm/checksum_64.h
@@ -51,12 +51,11 @@ long __csum_partial_copy_from_user(const void __user *src,
 
 static inline __wsum
 csum_and_copy_from_user(const void __user *src,
-                           void *dst, int len,
-                           __wsum sum, int *err)
+                           void *dst, int len)
 {
-       long ret = __csum_partial_copy_from_user(src, dst, len, sum);
+       long ret = __csum_partial_copy_from_user(src, dst, len, ~0U);
        if (ret < 0)
-               *err = -EFAULT;
+               return 0;
        return (__force __wsum) ret;
 }
 
@@ -70,12 +69,11 @@ long __csum_partial_copy_to_user(const void *src,
 
 static inline __wsum
 csum_and_copy_to_user(const void *src,
-                     void __user *dst, int len,
-                     __wsum sum, int *err)
+                     void __user *dst, int len)
 {
-       long ret = __csum_partial_copy_to_user(src, dst, len, sum);
+       long ret = __csum_partial_copy_to_user(src, dst, len, ~0U);
        if (ret < 0)
-               *err = -EFAULT;
+               return 0;
        return (__force __wsum) ret;
 }
 
diff --git a/arch/x86/include/asm/checksum_32.h 
b/arch/x86/include/asm/checksum_32.h
index 137a3033edcc..5948cde9e4ad 100644
--- a/arch/x86/include/asm/checksum_32.h
+++ b/arch/x86/include/asm/checksum_32.h
@@ -44,22 +44,19 @@ static inline __wsum csum_partial_copy_nocheck(const void 
*src, void *dst, int l
 }
 
 static inline __wsum csum_and_copy_from_user(const void __user *src,
-                                            void *dst, int len,
-                                            __wsum sum, int *err_ptr)
+                                            void *dst, int len)
 {
        __wsum ret;
+       int err = 0;
 
        might_sleep();
-       if (!user_access_begin(src, len)) {
-               if (len)
-                       *err_ptr = -EFAULT;
-               return sum;
-       }
+       if (!user_access_begin(src, len))
+               return 0;
        ret = csum_partial_copy_generic((__force void *)src, dst,
-                                       len, sum, err_ptr, NULL);
+                                       len, ~0U, &err, NULL);
        user_access_end();
 
-       return ret;
+       return err ? 0 : ret;
 }
 
 /*
@@ -177,23 +174,19 @@ static inline __sum16 csum_ipv6_magic(const struct 
in6_addr *saddr,
  */
 static inline __wsum csum_and_copy_to_user(const void *src,
                                           void __user *dst,
-                                          int len, __wsum sum,
-                                          int *err_ptr)
+                                          int len)
 {
        __wsum ret;
+       int err = 0;
 
        might_sleep();
-       if (user_access_begin(dst, len)) {
-               ret = csum_partial_copy_generic(src, (__force void *)dst,
-                                               len, sum, NULL, err_ptr);
-               user_access_end();
-               return ret;
-       }
+       if (!user_access_begin(dst, len))
+               return 0;
 
-       if (len)
-               *err_ptr = -EFAULT;
-
-       return (__force __wsum)-1; /* invalid checksum */
+       ret = csum_partial_copy_generic(src, (__force void *)dst,
+                                       len, ~0U, NULL, &err);
+       user_access_end();
+       return err ? 0 : ret;
 }
 
 #endif /* _ASM_X86_CHECKSUM_32_H */
diff --git a/arch/x86/include/asm/checksum_64.h 
b/arch/x86/include/asm/checksum_64.h
index 5339f5dfc776..9af3aed54c6b 100644
--- a/arch/x86/include/asm/checksum_64.h
+++ b/arch/x86/include/asm/checksum_64.h
@@ -135,10 +135,8 @@ extern __visible __wsum csum_partial_copy_generic(const 
void *src, const void *d
                                        int *src_err_ptr, int *dst_err_ptr);
 
 
-extern __wsum csum_and_copy_from_user(const void __user *src, void *dst,
-                                         int len, __wsum isum, int *errp);
-extern __wsum csum_and_copy_to_user(const void *src, void __user *dst,
-                                       int len, __wsum isum, int *errp);
+extern __wsum csum_and_copy_from_user(const void __user *src, void *dst, int 
len);
+extern __wsum csum_and_copy_to_user(const void *src, void __user *dst, int 
len);
 extern __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len);
 
 /**
diff --git a/arch/x86/lib/csum-wrappers_64.c b/arch/x86/lib/csum-wrappers_64.c
index 245f929a1c2c..ae2fb87e2274 100644
--- a/arch/x86/lib/csum-wrappers_64.c
+++ b/arch/x86/lib/csum-wrappers_64.c
@@ -22,13 +22,15 @@
  */
 __wsum
 csum_and_copy_from_user(const void __user *src, void *dst,
-                           int len, __wsum isum, int *errp)
+                           int len)
 {
+       int err = 0;
+       __wsum isum = ~0U;
+
        might_sleep();
-       *errp = 0;
 
        if (!user_access_begin(src, len))
-               goto out_err;
+               return 0;
 
        /*
         * Why 6, not 7? To handle odd addresses aligned we
@@ -53,20 +55,15 @@ csum_and_copy_from_user(const void __user *src, void *dst,
                }
        }
        isum = csum_partial_copy_generic((__force const void *)src,
-                               dst, len, isum, errp, NULL);
+                               dst, len, isum, &err, NULL);
        user_access_end();
-       if (unlikely(*errp))
-               goto out_err;
-
+       if (unlikely(err))
+               isum = 0;
        return isum;
 
 out:
        user_access_end();
-out_err:
-       *errp = -EFAULT;
-       memset(dst, 0, len);
-
-       return isum;
+       return 0;
 }
 EXPORT_SYMBOL(csum_and_copy_from_user);
 
@@ -83,16 +80,15 @@ EXPORT_SYMBOL(csum_and_copy_from_user);
  */
 __wsum
 csum_and_copy_to_user(const void *src, void __user *dst,
-                         int len, __wsum isum, int *errp)
+                         int len)
 {
-       __wsum ret;
+       __wsum ret, isum = ~0U;
+       int err = 0;
 
        might_sleep();
 
-       if (!user_access_begin(dst, len)) {
-               *errp = -EFAULT;
+       if (!user_access_begin(dst, len))
                return 0;
-       }
 
        if (unlikely((unsigned long)dst & 6)) {
                while (((unsigned long)dst & 6) && len >= 2) {
@@ -107,15 +103,13 @@ csum_and_copy_to_user(const void *src, void __user *dst,
                }
        }
 
-       *errp = 0;
        ret = csum_partial_copy_generic(src, (void __force *)dst,
-                                       len, isum, NULL, errp);
+                                       len, isum, NULL, &err);
        user_access_end();
-       return ret;
+       return err ? 0 : ret;
 out:
        user_access_end();
-       *errp = -EFAULT;
-       return isum;
+       return 0;
 }
 EXPORT_SYMBOL(csum_and_copy_to_user);
 
diff --git a/arch/x86/um/asm/checksum_32.h b/arch/x86/um/asm/checksum_32.h
index b9ac7c9eb72c..0b13c2947ad1 100644
--- a/arch/x86/um/asm/checksum_32.h
+++ b/arch/x86/um/asm/checksum_32.h
@@ -35,27 +35,4 @@ static __inline__ __sum16 csum_ipv6_magic(const struct 
in6_addr *saddr,
        return csum_fold(sum);
 }
 
-/*
- *     Copy and checksum to user
- */
-#define HAVE_CSUM_COPY_USER
-static __inline__ __wsum csum_and_copy_to_user(const void *src,
-                                                    void __user *dst,
-                                                    int len, __wsum sum, int 
*err_ptr)
-{
-       if (access_ok(dst, len)) {
-               if (copy_to_user(dst, src, len)) {
-                       *err_ptr = -EFAULT;
-                       return (__force __wsum)-1;
-               }
-
-               return csum_partial(src, len, sum);
-       }
-
-       if (len)
-               *err_ptr = -EFAULT;
-
-       return (__force __wsum)-1; /* invalid checksum */
-}
-
 #endif
diff --git a/arch/xtensa/include/asm/checksum.h 
b/arch/xtensa/include/asm/checksum.h
index 84e6a36fee6d..7958b18a5804 100644
--- a/arch/xtensa/include/asm/checksum.h
+++ b/arch/xtensa/include/asm/checksum.h
@@ -54,14 +54,16 @@ __wsum csum_partial_copy_nocheck(const void *src, void 
*dst, int len)
 #define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 static inline
 __wsum csum_and_copy_from_user(const void __user *src, void *dst,
-                                  int len, __wsum sum, int *err_ptr)
+                                  int len)
 {
-       if (access_ok(dst, len))
-               return csum_partial_copy_generic((__force const void *)src, dst,
-                                       len, sum, err_ptr, NULL);
-       if (len)
-               *err_ptr = -EFAULT;
-       return sum;
+       int err = 0;
+
+       if (!access_ok(dst, len))
+               return 0;
+
+       sum = csum_partial_copy_generic((__force const void *)src, dst,
+                                       len, ~0U, &err, NULL);
+       return err ? 0 : sum;
 }
 
 /*
@@ -242,15 +244,15 @@ static __inline__ __sum16 csum_ipv6_magic(const struct 
in6_addr *saddr,
  */
 #define HAVE_CSUM_COPY_USER
 static __inline__ __wsum csum_and_copy_to_user(const void *src,
-                                              void __user *dst, int len,
-                                              __wsum sum, int *err_ptr)
+                                              void __user *dst, int len)
 {
-       if (access_ok(dst, len))
-               return csum_partial_copy_generic(src,dst,len,sum,NULL,err_ptr);
+       int err = 0;
+       __wsum sum = ~0U;
 
-       if (len)
-               *err_ptr = -EFAULT;
+       if (!access_ok(dst, len))
+               return 0;
 
-       return (__force __wsum)-1; /* invalid checksum */
+       sum = csum_partial_copy_generic(src,dst,len,sum,NULL,&err);
+       return err ? 0 : sum;
 }
 #endif
diff --git a/include/net/checksum.h b/include/net/checksum.h
index 46754ba9d7b7..5b6664881a1e 100644
--- a/include/net/checksum.h
+++ b/include/net/checksum.h
@@ -24,26 +24,23 @@
 #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 static inline
 __wsum csum_and_copy_from_user (const void __user *src, void *dst,
-                                     int len, __wsum sum, int *err_ptr)
+                                     int len)
 {
        if (copy_from_user(dst, src, len))
-               *err_ptr = -EFAULT;
-       return csum_partial(dst, len, sum);
+               return 0;
+       return csum_partial(dst, len, ~0U);
 }
 #endif
 
 #ifndef HAVE_CSUM_COPY_USER
 static __inline__ __wsum csum_and_copy_to_user
-(const void *src, void __user *dst, int len, __wsum sum, int *err_ptr)
+(const void *src, void __user *dst, int len)
 {
-       sum = csum_partial(src, len, sum);
+       __wsum sum = csum_partial(src, len, ~0U);
 
        if (copy_to_user(dst, src, len) == 0)
                return sum;
-       if (len)
-               *err_ptr = -EFAULT;
-
-       return (__force __wsum)-1; /* invalid checksum */
+       return 0;
 }
 #endif
 
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index d5b7e204fea6..eccb0fe5a498 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1448,15 +1448,14 @@ size_t csum_and_copy_from_iter(void *addr, size_t 
bytes, __wsum *csum,
                return 0;
        }
        iterate_and_advance(i, bytes, v, ({
-               int err = 0;
                next = csum_and_copy_from_user(v.iov_base,
                                               (to += v.iov_len) - v.iov_len,
-                                              v.iov_len, ~0U, &err);
-               if (!err) {
+                                              v.iov_len);
+               if (next) {
                        sum = csum_block_add(sum, next, off);
                        off += v.iov_len;
                }
-               err ? v.iov_len : 0;
+               next ? 0 : v.iov_len;
        }), ({
                char *p = kmap_atomic(v.bv_page);
                sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
@@ -1490,11 +1489,10 @@ bool csum_and_copy_from_iter_full(void *addr, size_t 
bytes, __wsum *csum,
        if (unlikely(i->count < bytes))
                return false;
        iterate_all_kinds(i, bytes, v, ({
-               int err = 0;
                next = csum_and_copy_from_user(v.iov_base,
                                               (to += v.iov_len) - v.iov_len,
-                                              v.iov_len, ~0U, &err);
-               if (err)
+                                              v.iov_len);
+               if (!next)
                        return false;
                sum = csum_block_add(sum, next, off);
                off += v.iov_len;
@@ -1536,15 +1534,14 @@ size_t csum_and_copy_to_iter(const void *addr, size_t 
bytes, void *csump,
                return 0;
        }
        iterate_and_advance(i, bytes, v, ({
-               int err = 0;
                next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
                                             v.iov_base,
-                                            v.iov_len, ~0U, &err);
-               if (!err) {
+                                            v.iov_len);
+               if (next) {
                        sum = csum_block_add(sum, next, off);
                        off += v.iov_len;
                }
-               err ? v.iov_len : 0;
+               next ? 0 : v.iov_len;
        }), ({
                char *p = kmap_atomic(v.bv_page);
                sum = csum_and_memcpy(p + v.bv_offset,
-- 
2.11.0

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