[stgt] [PATCH] Fix COMPARE_AND_WRITE but leave it disabled.

Arne Redlich arne.redlich at googlemail.com
Fri Dec 7 20:31:26 CET 2012


2012/12/7 Ronnie Sahlberg <ronniesahlberg at gmail.com>:
> Fix the compare and write opcode but leave it disabled.
> It looks like consumers like vmware may be assuming that IF
> compare and write is present and if it works, then the target will also
> implement other opcodes like XCOPY etc.
>
> So lets fix the command so that it works, but wait with enabling it
> until we have everything else that the main consumer of this rare opcode
> expects and wants.
>
> Signed-off-by: Ronnie Sahlberg <ronniesahlberg at gmail.com>
> ---
>  usr/bs_rdwr.c |   21 +++++++++++++++++----
>  1 files changed, 17 insertions(+), 4 deletions(-)

I suppose this fell through the cracks last time around since I didn't
get any feedback: how is atomicity of the CAW guaranteed? AFAIU,
another bs thread could modify the data while a CAW is going on,
breaking the expected semantics. Or am I just overlooking something in
the code?

Thanks,
Arne
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