Paul Mackerras <pau...@ozlabs.org> writes: > 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.
This seems to have been broken since ~forever. Do we just not hit that case very often, or do we just incorrectly report checksum failures? Should it go to stable? cheers
