[ofa-general] [PATCH V3] infiniband/core: Enable loopback ofDR SMP responses from userspace

[Steve Welch]

I believe in the case of ib_mad_recv_done_handler(), the call
smi_check_forward_dr_smp() will return 0 indicating it should be
handled by the local stack because the hop pointer will equal
0 (in the case where the DR SMP response should be delivered to
the stack).  The smi_check_local_smp() call would not be reached.

The second part of the original fix is not required either
in ib_mad_recv_done_handler(); when the device process mad
routine does not reply or consume the MAD it uses the
original receive mad to deliver to the MAD to the local agent,
eliminating the need for the memcpy.

Steve
> -----Original Message-----
> From: Ralph Campbell [mailto:ralph.campbell at qlogic.com]
> Sent: Wednesday, October 17, 2007 7:33 PM
> To: swelch at systemfabricworks.com
> Cc: rdreier at cisco.com; sean.hefty at intel.com; general at lists.openfabrics.org
> Subject: Re: [ofa-general] [PATCH V3] infiniband/core: Enable loopback
> ofDR SMP responses from userspace
> 
> Steve's patch plus the attached patch for ib_ipath allows loopback
> to work and doesn't seem to obviously break anything.
> 
> I was wondering though about adding the code from
> smi_check_local_returning_smp() to smi_check_local_smp()
> instead of defining a separate function.
> That got me thinking about what happens when a return path DR SMP
> is received and ib_mad_recv_done_handler() calls smi_check_local_smp().
> Now I'm trying to convince myself one way or the other whether
> the same checks inib_mad_recv_done_handler() are needed or not.
> 
> On Wed, 2007-10-10 at 22:29 -0500, swelch at systemfabricworks.com wrote:
> >
> >   Sean, Roland,
> >
> >   This patch [v3] replaces the [v2] patch; it includes those changes but
> renames
> >   the smi function testing returning SMP requests to the name Hal
> recommends.
> >
> >   This patch allows userspace DR SMP responses to be looped back and
> delivered
> >   to a local mad agent by the management stack.
> >
> >   Thanks, Steve
> >
> > Signed-off-by: Steve Welch <swelch at systemfabricworks.com>
> > ---
> >  drivers/infiniband/core/mad.c |    6 +++---
> >  drivers/infiniband/core/smi.h |   18 +++++++++++++++++-
> >  2 files changed, 20 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/infiniband/core/mad.c
> b/drivers/infiniband/core/mad.c
> > index 6f42877..98148d6 100644
> > --- a/drivers/infiniband/core/mad.c
> > +++ b/drivers/infiniband/core/mad.c
> > @@ -701,7 +701,8 @@ static int handle_outgoing_dr_smp(struct
> ib_mad_agent_private *mad_agent_priv,
> >  	}
> >
> >  	/* Check to post send on QP or process locally */
> > -	if (smi_check_local_smp(smp, device) == IB_SMI_DISCARD)
> > +	if (smi_check_local_smp(smp, device) == IB_SMI_DISCARD &&
> > +	    smi_check_local_returning_smp(smp, device) == IB_SMI_DISCARD)
> >  		goto out;
> >
> >  	local = kmalloc(sizeof *local, GFP_ATOMIC);
> > @@ -752,8 +753,7 @@ static int handle_outgoing_dr_smp(struct
> ib_mad_agent_private *mad_agent_priv,
> >  		port_priv = ib_get_mad_port(mad_agent_priv->agent.device,
> >  					    mad_agent_priv->agent.port_num);
> >  		if (port_priv) {
> > -			mad_priv->mad.mad.mad_hdr.tid =
> > -				((struct ib_mad *)smp)->mad_hdr.tid;
> > +			memcpy(&mad_priv->mad.mad, smp, sizeof(struct
ib_mad));
> >  			recv_mad_agent = find_mad_agent(port_priv,
> >  						        &mad_priv->mad.mad);
> >  		}
> > diff --git a/drivers/infiniband/core/smi.h
> b/drivers/infiniband/core/smi.h
> > index 1cfc298..aff96ba 100644
> > --- a/drivers/infiniband/core/smi.h
> > +++ b/drivers/infiniband/core/smi.h
> > @@ -59,7 +59,8 @@ extern enum smi_action smi_handle_dr_smp_send(struct
> ib_smp *smp,
> >  					      u8 node_type, int port_num);
> >
> >  /*
> > - * Return 1 if the SMP should be handled by the local SMA/SM via
> process_mad
> > + * Return IB_SMI_HANDLE if the SMP should be handled by the local
> SMA/SM
> > + * via process_mad
> >   */
> >  static inline enum smi_action smi_check_local_smp(struct ib_smp *smp,
> >  						  struct ib_device *device)
> > @@ -71,4 +72,19 @@ static inline enum smi_action
> smi_check_local_smp(struct ib_smp *smp,
> >  		(smp->hop_ptr == smp->hop_cnt + 1)) ?
> >  		IB_SMI_HANDLE : IB_SMI_DISCARD);
> >  }
> > +
> > +/*
> > + * Return IB_SMI_HANDLE if the SMP should be handled by the local
> SMA/SM
> > + * via process_mad
> > + */
> > +static inline enum smi_action smi_check_local_returning_smp(struct
> ib_smp *smp,
> > +						   struct ib_device *device)
> > +{
> > +	/* C14-13:3 -- We're at the end of the DR segment of path */
> > +	/* C14-13:4 -- Hop Pointer == 0 -> give to SM */
> > +	return ((device->process_mad &&
> > +		ib_get_smp_direction(smp) &&
> > +		!smp->hop_ptr) ? IB_SMI_HANDLE : IB_SMI_DISCARD);
> > +}
> > +
> >  #endif	/* __SMI_H_ */
> 
> 
> 
> diff --git a/drivers/infiniband/hw/ipath/ipath_mad.c
> b/drivers/infiniband/hw/ipath/ipath_mad.c
> index 3d1432d..1978c34 100644
> --- a/drivers/infiniband/hw/ipath/ipath_mad.c
> +++ b/drivers/infiniband/hw/ipath/ipath_mad.c
> @@ -1434,7 +1434,7 @@ static int process_subn(struct ib_device *ibdev, int
> mad_flags,
>  		 * before checking for other consumers.
>  		 * Just tell the caller to process it normally.
>  		 */
> -		ret = IB_MAD_RESULT_FAILURE;
> +		ret = IB_MAD_RESULT_SUCCESS;
>  		goto bail;
>  	default:
>  		smp->status |= IB_SMP_UNSUP_METHOD;
> @@ -1516,7 +1516,7 @@ static int process_perf(struct ib_device *ibdev, u8
> port_num,
>  		 * before checking for other consumers.
>  		 * Just tell the caller to process it normally.
>  		 */
> -		ret = IB_MAD_RESULT_FAILURE;
> +		ret = IB_MAD_RESULT_SUCCESS;
>  		goto bail;
>  	default:
>  		pmp->status |= IB_SMP_UNSUP_METHOD;