On Mon, 2014-03-24 at 06:17 -0700, Eric Dumazet wrote:
> On Mon, 2014-03-24 at 10:30 +0000, David Laight wrote:
> > ip_fast_csum() either needs an explicit "m" constraint for the actual
> > buffer (and target) bytes, or the stronger "memory" constraint.
> > The 'volatile' is then not needed.
I am testing the following :
diff --git a/arch/x86/include/asm/checksum_64.h
b/arch/x86/include/asm/checksum_64.h
index e6fd8a026c7b..89d7fa8837b5 100644
--- a/arch/x86/include/asm/checksum_64.h
+++ b/arch/x86/include/asm/checksum_64.h
@@ -45,6 +45,9 @@ static inline __sum16 csum_fold(__wsum sum)
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
unsigned int sum;
+ struct full_ip_header {
+ unsigned int w[ihl];
+ };
asm(" movl (%1), %0\n"
" subl $4, %2\n"
@@ -67,8 +70,9 @@ static inline __sum16 ip_fast_csum(const void *iph, unsigned
int ihl)
are modified, we must also specify them as outputs, or gcc
will assume they contain their original values. */
: "=r" (sum), "=r" (iph), "=r" (ihl)
- : "1" (iph), "2" (ihl)
- : "memory");
+ : "1" (iph), "2" (ihl),
+ "m" (*(struct full_ip_header *) iph)
+ );
return (__force __sum16)sum;
}
--
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