[openib-general] [RFC] [PATCH] IB/uverbs: Don't serialize with ib_uverbs_idr_mutex

[Robert Walsh]

On Tue, 2006-06-13 at 10:55 -0700, Roland Dreier wrote:
>     Michael> Won't this let the user issue multiple modify QP commands
>     Michael> in parallel on the same QP? mthca at least does not
>     Michael> protect against such attempts, and doing this will
>     Michael> confuse the hardware.
> 
> Hmm, that's a good point.  But I did write the following in
> Documentation/infiniband/core_locking.txt:
> 
>   All of the methods in struct ib_device exported by a low-level
>   driver must be fully reentrant.  The low-level driver is required to
>   perform all synchronization necessary to maintain consistency, even
>   if multiple function calls using the same object are run
>   simultaneously.
> 
>   The IB midlayer does not perform any serialization of function calls.
> 
> So I guess this is a bug in mthca.

We have a similar problem in resource checking - we were relying on the
idr lock to keep us safe.  I'll fix that up, too.

Regards,
 Robert.

-- 
Robert Walsh                                 Email: rjwalsh at pathscale.com
PathScale, Inc.                              Phone: +1 650 934 8117
2071 Stierlin Court, Suite 200                 Fax: +1 650 428 1969
Mountain View, CA 94043.
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