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Subject: Re: [PATCH v2 1/8] ib_mad: incoming sminfo SMPs gets discarded if no
 process_mad function is registered
To: Knut Omang <knut.omang@oracle.com>, Doug Ledford <dledford@redhat.com>
References: <cover.15d71ac2c57534f1170c2c48374d3841ed75e676.1474049924.git-series.knut.omang@oracle.com>
 <66d69383a3376018d99c025cd188150f6673b209.1474049924.git-series.knut.omang@oracle.com>
Cc: linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
        Sean Hefty <sean.hefty@intel.com>,
        Hal Rosenstock <hal.rosenstock@gmail.com>,
        Ira Weiny <ira.weiny@intel.com>, Sagi Grimberg <sagi@grimberg.me>,
        Christoph Hellwig <hch@infradead.org>,
        Bart Van Assche <bart.vanassche@sandisk.com>,
        Dag Moxnes <dag.moxnes@oracle.com>, Mark Bloch <markb@mellanox.com>,
        Dean Luick <dean.luick@intel.com>
From: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Organization: Oracle Corporation
Message-ID: <b57491e1-e36b-c331-8360-557310d15002@oracle.com>
Date: Fri, 16 Sep 2016 13:28:09 -0700
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On 9/16/2016 11:31 AM, Knut Omang wrote:
> From: Dag Moxnes <dag.moxnes@oracle.com>
>
> The process_mad function is an optional IB driver entry point
> allows a driver to intercept or modify MAD traffic.
>
> This fix allows MAD traffic to flow down to the device also
> when MAD traffic is completely handled by the device and
> no process_mad function is provided.
>
> SIF, the new Oracle Infiniband HCA, is the first HCA
> where the device itself makes all decision wrt MAD processing.
> Up till now devices either supports MAD, and do then
> implement the process_mad entry point, or do not
> support MAD at all, and then do not implement process_mad.
>
> SIF introduces a 3rd case: Supports MAD
> but do not terminate any MAD requests in the driver.
> This case is not handled well by the current code.
>
> The problem is that the handle_outgoing_dr_smp function
> has an implicit assumption that some packets are handled
> by the process_mad function itself.
>
> There is no way to provide return values from the process_mad
> function that ensures that packets are always forwarded to the device,
> so the only viable solution without breaking the API
> seems to be to not implement process_mad.

No SOBs ?