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

[FUJITA Tomonori]

On Fri, 7 Dec 2012 20:31:26 +0100
Arne Redlich <arne.redlich at googlemail.com> wrote:

> 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?

The spec requires such atomicity? Yeah, I'm too lazy to check the spec.
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