[openib-general] OpenSM/osm_sa_mcmember_record.c: In __osm_mcmr_rcv_leave_mgrp, eliminate unneeded lock acquisition

[Hal Rosenstock]

Hi Eitan,

On Sat, 2006-12-02 at 10:51, Eitan Zahavi wrote:
> Hi Hal,
> 
> I see you are doing some work on optimizing the locking scheme in the 
> multicast registration flow
>  (join and leave).

Yes and it goes further than this. Additional patch(es) will be coming.

So does this look OK to you ?

> What kind of testing do you do?

Two fold:
1. Tested in another simulated environment
2. Tested in a large cluster where there is a larger join/leave race
issue which started us down the road looking at these code paths more

> In the simulated environment we do not have currently a test that will 
> fire pairs of join/leave or
> join/leave/join and verify correctness.Maybe we should have one written.

Sure; you are welcome to add one. I don't have time to do this now.

-- Hal

> Eitan
> 
> Hal Rosenstock wrote:
> > OpenSM/osm_sa_mcmember_record.c: In __osm_mcmr_rcv_leave_mgrp, eliminate
> > unneeded lock acquisition
> >
> > Signed-off-by: Sasha Khapyorsky <sashak at voltaire.com>
> > Signed-off-by: Hal Rosenstock <halr at voltaire.com>
> >
> > diff --git a/osm/opensm/osm_sa_mcmember_record.c b/osm/opensm/osm_sa_mcmember_record.c
> > index f7f879b..d6c6968 100644
> > --- a/osm/opensm/osm_sa_mcmember_record.c
> > +++ b/osm/opensm/osm_sa_mcmember_record.c
> > @@ -1459,6 +1459,8 @@ __osm_mcmr_rcv_leave_mgrp(
> >            new_join_state | (p_mcm_port->scope_state & 0xf0);
> >  
> >          mcmember_rec.scope_state = p_mcm_port->scope_state;
> > +
> > +        CL_PLOCK_RELEASE( p_rcv->p_lock );
> >        }
> >        else
> >        {
> > @@ -1475,10 +1477,6 @@ __osm_mcmr_rcv_leave_mgrp(
> >                     "__osm_mcmr_rcv_leave_mgrp: ERR 1B09: "
> >                     "osm_sm_mcgrp_leave failed\n" );
> >          }
> > -
> > -        CL_PLOCK_EXCL_ACQUIRE(p_rcv->p_lock);
> > -        /* Note: The deletion of the mgrp itself will be done in the callback
> > -           for the multicast tree updating (osm_mcast_mgr_process_mgrp_cb) */
> >        }
> >      }
> >      else
> > @@ -1511,8 +1509,6 @@ __osm_mcmr_rcv_leave_mgrp(
> >      goto Exit;
> >    }
> >  
> > -  CL_PLOCK_RELEASE( p_rcv->p_lock );
> > -
> >    /* Send an SA response */
> >    __osm_mcmr_rcv_respond( p_rcv, p_madw, &mcmember_rec );
> >  
> >
> >
> >
> >
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