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    Subject[patch 48/59] SPARC32: Fix over-optimization by GCC near ip_fast_csum.
    -stable review patch.  If anyone has any objections, please let us know.
    ------------------

    From: Bob Breuer <breuerr@mc.net>

    In some cases such as:
    iph->check = 0;
    iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
    GCC may optimize out the previous store.

    Observed as a failure of NFS over udp (bad checksums on ip fragments)
    when compiled with GCC 3.4.2.

    Signed-off-by: Bob Breuer <breuerr@mc.net>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Chris Wright <chrisw@sous-sol.org>
    ---
    include/asm-sparc/checksum.h | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- linux-2.6.19.2.orig/include/asm-sparc/checksum.h
    +++ linux-2.6.19.2/include/asm-sparc/checksum.h
    @@ -159,7 +159,7 @@ static inline unsigned short ip_fast_csu
    "xnor\t%%g0, %0, %0"
    : "=r" (sum), "=&r" (iph)
    : "r" (ihl), "1" (iph)
    - : "g2", "g3", "g4", "cc");
    + : "g2", "g3", "g4", "cc", "memory");
    return sum;
    }

    --
    -
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