Messages in this thread | | | Date | Sun, 19 Nov 2006 20:57:11 +0000 | From | Al Viro <> | Subject | Re: reiserfs NET=n build error |
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On Sun, Nov 19, 2006 at 11:04:33AM -0800, Randy Dunlap wrote: > Andi Kleen wrote: > >>>I would copy a relatively simple C implementation, like > >>>arch/h8300/lib/checksum.c > >>As long as the h8300 version has the same output as the x86 version. > > > >The trouble is that the different architecture have different output > >for csum_partial. So you already got a bug when someone wants to move > >file systems. > > > >-Andi > > That argues for having only one version of it (in a lib.; my preference) > -or- Every module having its own local copy/version of it. :(
Wrong. csum_partial() result is defined modulo 0xffff and it's basically "whatever's convenient as intermediate for this architecture".
reiserfs use of it is just plain broken. net/* is fine, since all final uses are via csum_fold() or equivalents.
Note that reiserfs use is broken in another way: it takes fixed-endian value and feeds it to cpu_to_le32(). IOW, even if everything had literally the same csum_partial(), the value it shits on disk would be endian-dependent.
As for net/*, with proper types it's pretty straightforward. See davem's net-2.6.20 for that... - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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