]> git.baikalelectronics.ru Git - kernel.git/commit
powerpc/64: Fix checksum folding in csum_tcpudp_nofold and ip_fast_csum_nofold
authorPaul Mackerras <paulus@ozlabs.org>
Thu, 3 Nov 2016 05:10:55 +0000 (16:10 +1100)
committerMichael Ellerman <mpe@ellerman.id.au>
Wed, 25 Jan 2017 02:34:18 +0000 (13:34 +1100)
commitb492f7e4e07a28e706db26cf4943bb0911435426
tree2e5ce673c7553a9faccc17100785235cc8df9d0d
parent14a41d6b7572026cf8fc88ee72e81b6b40db2ec0
powerpc/64: Fix checksum folding in csum_tcpudp_nofold and ip_fast_csum_nofold

These functions compute an IP checksum by computing a 64-bit sum and
folding it to 32 bits (the "nofold" in their names refers to folding
down to 16 bits).  However, doing (u32) (s + (s >> 32)) is not
sufficient to fold a 64-bit sum to 32 bits correctly.  The addition
can produce a carry out from bit 31, which needs to be added in to
the sum to produce the correct result.

To fix this, we copy the from64to32() function from lib/checksum.c
and use that.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
arch/powerpc/include/asm/checksum.h